Sensor Assembly of a Microneedle Array-Based Continuous Analyte Monitoring Device

Abstract

Aspects of the present subject matter relate to a sensor assembly of an analyte monitoring device that includes one or more microneedle arrays. The aspects relate to components and architecture of a sensor assembly for implementing power and processing aspects of a microneedle array-based continuous analyte monitoring device for detection and measurement of an analyte. A source of a power-on event is determined, and the analyte monitoring device is transitioned to a mode corresponding to the determined source. When the power-on event is determined to be a valid power-on event, the analyte monitoring device is transitioned to a mode corresponding to the type of the valid power-on event.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 358,459, filed on July 5, 2022, the content of which is hereby incorporated by reference in its entirety.

[0002] The present invention generally relates to the field of analyte monitoring, such as continuous glucose monitoring.

Background Art

[0003] Diabetes is a chronic disease in which the body does not produce or does not properly utilize insulin, a hormone that regulates blood glucose. Insulin can be administered to diabetic patients to help regulate blood glucose levels, but even so, blood glucose levels must be carefully monitored to help ensure that the timing and dosage are appropriate. If diabetic patients do not properly manage their condition, they can suffer from various complications resulting from hyperglycemia (high blood glucose) or hypoglycemia (low blood glucose).

[0004] A blood glucose monitor helps diabetic patients manage their condition by measuring blood glucose levels from a blood sample. For example, a diabetic patient can collect a blood sample via a fingertip puncture sampling mechanism, transfer the blood sample to a test strip with a suitable reagent(s) that reacts with the blood sample, and use a blood glucose monitor to analyze the test strip and measure the glucose level in the blood sample. However, patients using this process can typically only measure their glucose levels at discrete time instances and may not be able to capture hyperglycemic or hypoglycemic states in a timely manner. Even more recently, various glucose monitors are continuous glucose monitors (CGMs), which include an implantable transdermal electrochemical sensor used to continuously detect and quantify blood glucose levels by proxy measurement of glucose levels in interstitial fluid under the skin. However, conventional CGM devices also have weaknesses including tissue trauma from insertion and signal delay (e.g., due to the time required for the glucose analyte to diffuse from the capillary source to the sensor). These weaknesses also lead to several drawbacks such as pain experienced by the patient when the electrochemical sensor is inserted and limited accuracy of glucose measurement especially when blood glucose levels are changing rapidly. Therefore, there is a need for a novel and improved analyte monitoring system.

Summary of the Invention

Means for Solving the Problems

[0005] In some variations, a method of operating an analyte monitoring device configured to be inserted into a user's skin includes determining, by a controller of the analyte monitoring device, a source of a power-on event, where the source of the power-on event is power received from a connection to a battery or an ambient power generation module, and transitioning the analyte monitoring device to an operating mode corresponding to the determined source of the power-on event. When the determined source of the power-on event is a connection to a battery, the corresponding operating mode includes a startup mode, and when the source of the power-on event is power received from an ambient power generation module, the corresponding operating mode includes a reset mode.

[0006] In some variations, the analyte monitoring device includes a microneedle array configured to be inserted into a user's skin and acquire analog current measurements, a battery, an ambient power generation module, and a controller configured to determine a source of a power-on event, where the source of the power-on event is power received from a connection to a battery or an ambient power generation module, and transition the analyte monitoring device to an operating mode corresponding to the determined source of the power-on event. When the determined source of the power-on event is a connection to a battery, the corresponding operating mode includes a startup mode, and when the source of the power-on event is power received from an ambient power generation module, the corresponding operating mode includes a reset mode.

[0007] In some variations, a method of operating an analyte monitoring device configured to be inserted into a user's skin includes determining, by a controller of the analyte monitoring device, that a power-on event is a valid power-on event, where a valid power-on event includes a transition of the analyte monitoring device to an operable state or an intentional placement within a communication field of the analyte monitoring device, and after determining that the power-on event is a valid power-on event, transitioning the analyte monitoring device to a mode corresponding to each valid power-on event.

[0008] In some variations, the analyte monitoring device includes a microneedle array configured to be inserted into a user's skin and acquire analog current measurements, and a controller configured to determine that a power-on event is a valid power-on event, where a valid power-on event includes a transition of the analyte monitoring device to an operable state or an intentional placement within a communication field of the analyte monitoring device, and after determining that the power-on event is a valid power-on event, transitioning the analyte monitoring device to a mode corresponding to each valid power-on event.

[0009] In some variations, a method of operating an analyte monitoring device configured to be inserted into a user's skin includes determining, by a controller of the analyte monitoring device, that a power-on event is a valid power-on event by identifying whether the analyte monitoring device is in an operable state, and in response to determining that the power-on event is a valid power-on event, transitioning the analyte monitoring device to an idle mode.

[0010] In some variations, the analyte monitoring device includes a microneedle array configured to be inserted into the user's skin and obtain analog current measurements, and a controller configured to determine that a power-on event is a valid power-on event by identifying whether the analyte monitoring device is in a usable state, and in response to determining that the power-on event is a valid power-on event, shift the analyte monitoring device to an idle mode.

[0011] In some variations, the sensor assembly of the analyte monitoring device includes a microneedle array assembly and an electronics assembly. The microneedle array assembly may include a microneedle array configured to obtain analog current measurements indicative of the concentration of an analyte. The electronics assembly may include a power source, an analog front end configured to convert the analog current measurements to digital values, a microcontroller configured to process the digital values, a power connection circuit including a switch configured to couple the power source to the microcontroller and the analog front end, and a light detection circuit configured to generate a signal to the power connection circuit in response to a trigger event, the signal including an instruction to close the switch, thereby establishing a connection between the power source and the microcontroller and between the power source and the analog front end. The connection between the light detection circuit and the power connection circuit may be established upon connection of the microneedle array assembly and the electronics assembly.

[0012] In some variations, the method, in an analyte monitoring device comprising a microneedle array, establishes a connection between a power supply connection circuit and a light detection circuit, the power supply connection circuit comprising a switch configured to establish connections between the power supply and a microcontroller and between the power supply and an analog front end; in response to a trigger event, establishes connections between the power supply and the microcontroller and between the power supply and the analog front end, the trigger event being detected by the light detection circuit; confirms insertion of the microneedle array into the user's skin; and in response to insertion of the microneedle array, shifts the analog front end to active sensing.

[0013] In some variations, a method of operating an analyte monitoring device configured to be inserted into a user's skin includes applying, by an analog front end of the analyte monitoring device, a first bias potential between a first working electrode and a reference point; measuring a current resulting as a first outcome at the first working electrode; applying, by the analog front end, a second bias potential between a second working electrode and the reference point; measuring a current resulting as a second outcome at the second working electrode; and in response to a determination that at least one of the current resulting as the first outcome and the current resulting as the second outcome is within a predetermined threshold, transitioning the analyte monitoring device to an operating mode in which an operating bias potential is applied. The analyte monitoring device comprises a microneedle array, the microneedle array comprising at least two working electrodes, a reference electrode, and a counter electrode, each disposed on a respective microneedle of the microneedle array.

[0014] In some variations, a method of operating an analyte monitoring device configured to be inserted into a user's skin includes applying a first bias potential by an analog front end of the analyte monitoring device, the first bias potential being applied between a first working electrode and a reference point, measuring a current resulting as a first result at the first working electrode, and in response to a determination that the current resulting as the first result is within a predetermined threshold, transitioning the analyte monitoring device to an operating mode in which an operating bias potential is applied, and in the operating mode, applying the operating bias potential to at least a second working electrode. The analyte monitoring device includes a micro-needle array, the micro-needle array including at least two working electrodes, a reference electrode, and a counter electrode, each disposed on a respective micro-needle of the micro-needle array.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0036] Non-limiting examples of various aspects and variations of the present invention are described herein and shown in the accompanying drawings.

[0037] Aspects of the present subject matter relate to a sensor assembly that includes one or more microneedle arrays of an analyte monitoring device. More specifically, the aspects relate to the components and architecture of a sensor assembly for implementing the power and processing aspects of a microneedle array-based continuous analyte monitoring device for the detection and measurement of analytes.

[0038] As generally described herein, an analyte monitoring system can include an analyte monitoring device that is worn by a user and includes one or more sensors for monitoring at least one analyte of the user. The sensors can include, for example, one or more electrodes configured to perform an electrochemical detection of at least one analyte. The analyte monitoring device can communicate sensor data to an external computing device for storage, display, and / or analysis of the sensor data.

[0039] For example, as shown in FIG. 1, an analyte monitoring system 100 can include an analyte monitoring device 110 worn by a user. The analyte monitoring device 110 may be a continuous analyte monitoring device (e.g., a continuous glucose monitoring device). The analyte monitoring device 110 can include, for example, a microneedle array that includes at least one electrochemical sensor for detecting and / or measuring one or more analytes in a user's body fluid. In some variations, the analyte monitoring device 110 may be applied to the user using a suitable applicator 160, or in some variations, the analyte monitoring device 110 may be applied manually. The analyte monitoring device 110 can include one or more processors for performing analysis of sensor data, and / or a communication module (e.g., a wireless communication module) configured to communicate sensor data to a mobile computing device 102 (e.g., a smartphone) or other suitable computing device. In some variations, the mobile computing device 102 can include one or more processors for executing a mobile application to process sensor data (e.g., display of data, analysis of trend-related data, etc.) and / or provide appropriate warnings or other notifications related to the sensor data and / or its analysis. In some variations, the mobile computing device 102 can perform sensor data analysis locally, but other computing devices can alternatively or additionally analyze the sensor data remotely and communicate information related to such analysis to the mobile computing device 102 (or other suitable user interface) for display to the user. Further, in some variations, the mobile computing device 102 can be configured to communicate sensor data and / or analysis of the sensor data to one or more storage devices 106 (e.g., a server) via the network 104 to archive data related to the user of the analyte monitoring device 110 and / or other suitable information.

[0040] The analyte monitoring device described herein has features that improve several characteristics advantageous for continuous analyte monitoring devices such as continuous glucose monitoring (CGM) devices. For example, the analyte monitoring device described herein has improved sensitivity (the amount of sensor signal generated per given concentration of the target analyte), improved selectivity (exclusion of endogenous and exogenous circulating compounds that may interfere with detection of the target analyte), and improved stability to help minimize changes in sensor response over time due to storage and operation of the analyte monitoring device. Further, compared to conventional continuous analyte monitoring devices, the analyte monitoring device described herein has a shorter warm-up time that enables the sensor to quickly provide a stable sensor signal after implantation, and a short response time that enables the sensor to quickly provide a stable sensor signal after a change in the analyte concentration of the user. Further, as described in more detail below, the analyte monitoring device described herein can be applied to and function within various wearing sites, providing painless sensor insertion to the user. Other characteristics such as biocompatibility, sterilizability, and mechanical integrity are also optimized in the analyte monitoring device described herein.

[0041] The analyte monitoring system described herein may be described with reference to monitoring of glucose (e.g., in users having type 2 diabetes, type 1 diabetes), although such a system may be configured to additionally or alternatively sense and monitor other suitable analytes. As described in more detail below, suitable target analytes for detection may include, for example, glucose, ketones, lactate, and cortisol. One type of target analyte may be monitored, or multiple types of target analytes may be monitored simultaneously (e.g., in the same analyte monitoring device). For example, monitoring of other target analytes may enable monitoring of other signs such as stress (e.g., through detection of an increase in cortisol and glucose) and ketoacidosis (e.g., through detection of an increase in ketones).

[0042] Exemplary variant forms of the analyte monitoring device, the analyte monitoring system, and methods of using the same are described in further detail below.

[0043] As shown in FIG. 2A, in some variants, the analyte monitoring device 110 may generally include a housing 112 and a microneedle array 140 extending outwardly from the housing 112. The housing 112 may be, for example, a wearable housing configured to be worn on the user's skin such that the microneedle array 140 extends at least partially into the user's skin. For example, the housing 112 may include an adhesive such that the analyte monitoring device 110 is a simple and easy-to-use skin adhesive patch for application to the user. The microneedle array 140 is configured to pierce the user's skin and may include one or more electrochemical sensors (e.g., electrodes) configured to measure one or more target analytes accessible after the microneedle array 140 has pierced the user's skin. In some variants, the analyte monitoring device 110 may be integrated or incorporated as a single unit, which may be disposable (e.g., used for a period of time and replaced with another instance of the analyte monitoring device 110).

[0044] The electronic device system 120 can include various electronic components such as a sensor circuit 124 that is at least partially disposed within the housing 112 and configured to perform signal processing (e.g., biasing and reading of an electrochemical sensor, conversion of an analog signal from the electrochemical sensor to a digital signal, etc.). The electronic device system 120 can also include at least one microcontroller 122 for controlling the analyte monitoring device 110, at least one communication module 126, at least one power source 130, and / or various other suitable passive circuits 127. The microcontroller 122 can be configured to interpret, for example, the digital signals output from the sensor circuit 124 (e.g., by executing routines programmed in firmware), perform various suitable algorithms or mathematical conversions (e.g., calibration, etc.), and / or route the processed data to and from the communication module 124. In some variations, the communication module 126 can include a suitable wireless transceiver (e.g., a Bluetooth® transceiver, a short-range communication antenna, etc.) for communicating data with an external computing device 102 via one or more antennas 128. For example, the communication module 126 can be configured to provide one-way and / or two-way communication of data with an external computing device 102 that pairs with the analyte monitoring device 110. The power source 130 can supply power to the analyte monitoring device 110 for the electronic device system and the like. The power source 130 can include a battery or other suitable power source and, in some variations, can be rechargeable and / or replaceable. The passive circuit 127 can include various non-powered electrical circuits (e.g., resistors, capacitors, inductors, etc.) that provide interconnections between other electronic components and the like. The passive circuit 127 can be configured to perform, for example, noise reduction, biasing, and / or other purposes. In some variations, the electronic components within the electronic device system 120 can be disposed on one or more printed circuit boards (PCBs) that can be, for example, rigid, semi-rigid, or flexible. Further details of the electronic device system 120 are described further below.

[0045] In some variations, the analyte monitoring device 110 may further include one or more additional sensors 150 for providing additional information that may be relevant to user monitoring. For example, the analyte monitoring device 110 may further include at least one temperature sensor (e.g., a thermistor) configured to measure the temperature of the skin, thereby enabling temperature compensation of the sensor measurements obtained by the microneedle array electrochemical sensor.

[0046] As shown in the schematic diagram of FIG. 2A of the analyte monitoring device 110, in contrast to conventional CGM systems that typically incorporate components into a plurality of physically separate units, the electronic device system 120 may be integrated within the housing 112 such that the electronic device system 120 can be combined with a sensing element (e.g., the microneedle array 140) as part of a single unit.

[0047] In some variations, the microneedle array 140 of the analyte monitoring device 110 may be configured to pierce the user's skin. As shown in FIG. 2B, when the device 110 is worn by the user, the microneedle array 140 can extend into the user's skin such that the electrodes on the distal region of the microneedles remain in the dermis. Specifically, in some variations, the microneedles can be designed to penetrate the skin and access the upper skin regions of the skin (e.g., the dermal papillary layer and the upper reticular dermal layer) to enable the electrodes to access the interstitial fluid surrounding the cells of these layers. For example, in some variations, the microneedles can generally have a height in the range of at least 350 μm to about 515 μm. In some variations, one or more microneedles may extend from the housing such that the distal ends of the electrodes on the microneedles are disposed less than about 5 mm from the skin contact surface of the housing, less than about 4 mm from the housing, less than about 3 mm from the housing, less than about 2 mm from the housing, or less than about 1 mm from the housing.

[0048] In contrast to conventional continuous analyte monitoring devices (e.g., CGM devices) that typically include sensors embedded about 8 mm to about 10 mm beneath the skin surface in the subcutaneous tissue or fat layer of the skin, the analyte monitoring device 110 has a shallower microneedle insertion depth of about 0.25 mm (such that the electrodes are embedded in the upper skin region of the skin), which provides numerous advantages. These advantages include, at least, access to interstitial fluid containing one or more target analytes for detection, since it has been found that at least some types of analyte measurements in interstitial fluid closely correlate with analyte measurements in blood. For example, glucose measurements performed using an electrochemical sensor accessing interstitial fluid have been found to advantageously correlate highly linearly with blood glucose measurements. Thus, glucose measurements based on interstitial fluid are highly representative of blood glucose measurements.

[0049] Furthermore, due to the shallower microneedle insertion depth of the analyte monitoring device 110, a reduction in time delay in analyte detection is obtained compared to conventional continuous analyte monitoring devices. Such a shallower insertion depth positions the sensor surface in proximity to (e.g., within several hundred micrometers or less) the highly perfused capillary bed of the reticular dermis, such that the diffusion lag from the capillary to the sensor surface becomes negligibly small. The diffusion time is t = x 2 / (2D), where t is the diffusion time, x is the diffusion distance, and D is the mass diffusivity of the analyte of interest. Thus, if the analyte sensing element is positioned twice as far from the analyte source in the capillary, the diffusion delay time is quadrupled. Therefore, conventional analyte sensors (which are present in adipose tissue with very poor angiogenesis under the dermis) have a significantly longer diffusion distance from the vasculature in the dermis, resulting in a substantial diffusion waiting time (e.g., typically 5 - 20 minutes). In contrast, the shallower micro-needle insertion depth of the analyte monitoring device 110 benefits from a low diffusion waiting time from the capillary to the sensor, thereby reducing the time delay in analyte detection and providing more accurate results in real-time or near real-time. For example, in some embodiments, the diffusion waiting time can be less than 10 minutes, less than 5 minutes, or less than 3 minutes.

[0050] Furthermore, when the micro-needle array is in the upper skin region, the lower dermis below the micro-needle array contains a very high level of angiogenesis and perfusion to support dermal metabolism, which provides a barrier function that enables thermoregulation (through vasoconstriction and / or vasodilation) and helps to stabilize the sensing environment around the micro-needles. Yet another advantage of the shallower insertion depth is that, since the upper dermal layer lacks pain receptors, the sensation of pain is reduced when the micro-needle array pierces the user's skin, providing a more comfortable and less invasive user experience.

[0051] Thus, the analyte monitoring devices and methods described herein enable improved continuous monitoring of one or more target analytes of a user. For example, as described above, the analyte monitoring device can be simple and easy to apply, thereby improving usability and user compliance. Furthermore, analyte measurements in interstitial fluid can provide very accurate analyte detection. Additionally, compared to conventional continuous analyte monitoring devices, the insertion of the micro-needle array and its sensors can be less invasive and potentially less painful for the user. Further advantages of other aspects of the analyte monitoring devices and methods are described in more detail below.

[0052] Figures 3A - 3D show aspects of the analyte monitoring device 110. Figures 3A - 3D show an upper perspective view, a side view, a bottom view, and an exploded view of the analyte monitoring device 110, respectively.

[0053] The analyte monitoring device 110 may include a housing that at least partially surrounds or encloses such components (e.g., electronic components) of the analyte monitoring device 110 for protecting other components of the analyte monitoring device 110 and the like. For example, the housing may be configured to help prevent dust and moisture from entering the analyte monitoring device 110. In some variations, an adhesive layer can attach the housing to the user's surface (e.g., skin) while allowing the microneedle array 140 to extend outwardly from the housing into the user's skin. Further, in some variations, the housing can generally include rounded edges or corners and / or be thin to reduce interference with clothing or the like worn by the user.

[0054] For example, as shown in Figures 3A - 3D, an exemplary variation of the analyte monitoring device 110 may include a housing cover 320 and a base plate 330 configured to at least partially surround the internal components of the analyte monitoring device 110. For example, the housing cover 320 and the base plate 330 may provide an enclosure for the sensor assembly 350 including the microneedle array 140 and electronic components. When assembled, the microneedle array 140 extends outwardly from a portion of the base plate 330 in the skin-facing direction (e.g., downward) of the analyte monitoring device 110.

[0055] The housing cover 320 and the base plate 330 may include one or more rigid or semi-rigid protective shell components that can be coupled to each other, for example, via suitable fasteners (e.g., mechanical fasteners), mechanically coupled or mating features, and / or engineering fits. The housing cover 320 and the base plate 330 can include rounded edges and corners, and / or other non-abrasive features. When coupled to each other, the housing cover 320 and the base plate 330 can form an internal volume for housing internal components such as the sensor assembly 350. For example, the internal components disposed within the internal volume may be arranged in a compact and thin laminate as the sensor assembly 350.

[0056] The analyte monitoring device 110 may include one or more adhesive layers for attaching the analyte monitoring device 110 (e.g., the housing cover 320 and the base plate 330 coupled to each other) to the surface of a user (e.g., the skin). As shown in FIG. 3D, the one or more adhesive layers may include an inner adhesive layer 342 and an outer adhesive layer 344. The inner adhesive layer 342 may adhere to the base plate 330, and the outer adhesive layer 344 may adhere to the inner adhesive layer 342 and provide an adhesive for adhering to the user's skin (e.g., temporarily) on its outward-facing side surface. Both the inner adhesive layer 342 and the outer adhesive layer 344 function as a double-sided adhesive for adhering the analyte monitoring device 110 to the user's skin. The outer adhesive layer 344 may be protected by a release liner that the user removes prior to application to the skin to expose the adhesive. In some variations, a single adhesive layer is provided. In some variations, the outer adhesive layer 344 and / or the inner adhesive layer 342 may have an outer perimeter that extends further away from the outer periphery or the perimeter of the housing cover 320 and the base plate 330. This may increase the surface area for attachment and increase the stability of the retention or attachment to the user's skin. The inner adhesive layer 342 and / or the outer adhesive layer 344 may each have an opening that allows the micro-needle array 140 extending outwardly, as further described below, to pass through. The openings of the inner adhesive layer 342 and the outer adhesive layer 344 may generally be aligned with each other, but in some variations, they may be sized differently such that one opening is smaller than the other. In some variations, the openings are substantially the same size.

[0057] The base plate 330 has a first surface (e.g., an outer exposed surface) on the opposite side of the second surface, and functions as a support and / or connection structure, as well as a protective cover for the sensor assembly 350. The base plate 330 is sized and shaped to be attached to the housing cover 320. The base plate 330 can be molded to fit snugly within the housing cover 320 such that the outer edge of the base plate 330 aligns with the corresponding edge of the opening of the housing 320. This alignment can be such that there is no gap between the outer edge of the base plate 330 and the corresponding edge of the opening of the housing cover 320.

[0058] A connection member 332 may be formed in a central region or a substantially central region of the first surface of the base plate 330. The connection member 332 has a first surface that is substantially parallel to the first surface of the base plate 330. The side walls extend from the edges of the first surface of the connection member 332 to the first surface of the base plate 330. The remaining portion of the first surface of the base plate 330 surrounding the connection member 332 may be flat or substantially flat. One or more connector features 336 extend outwardly from the side walls of the connection member 332 and may releasably engage corresponding connectors of the micro needle enclosure. The first surface and the side walls of the connection member 332 partially define a cavity. The cavity may be further defined by a portion of the base plate 330 adjacent to (e.g., below) the connection member 332. The cavity has an opening on the second surface of the base plate 330 and is accessible. An aperture 334 is formed through the first surface of the connection member 332. The aperture 334 may be sized and shaped such that the micro needle array 140 fits snugly within the aperture 334 and extends therethrough. For example, the side walls of the micro needle array 140 may be aligned with the corresponding side walls of the aperture 334. In some variations, the aperture 334 may be sized and shaped to correspond to the region surrounding the micro needle array 140. The openings in the inner adhesive layer 342 and the outer adhesive layer 344 are sized such that the connection member 332 extends through the openings without interfering with the inner adhesive layer 342 and the outer adhesive layer 344. For example, the diameter of the opening in the inner adhesive layer 342 and the diameter of the opening in the outer adhesive layer 344 are larger than those of the connection member 332.

[0059] The housing cover 320 and the base plate 330 shown in FIGS. 3A to 3D are substantially circular, and the housing cover 320 has a dome shape. However, in other deformation forms, the housing cover 320 and the base plate 330 may have any suitable shape. For example, in other deformation forms, the housing cover 320 and the base plate 330 may be substantially prismatic, and may have an elliptical, triangular, rectangular, pentagonal, hexagonal, or other suitable shape. The outer adhesive layer 344 may extend outward from the housing cover 320 and the base plate 330 and may extend beyond the outer periphery of the housing cover 320. The outer adhesive layer 344 may be circular as shown in FIGS. 3A to 3D, or may have an elliptical, triangular, rectangular, pentagonal, hexagonal, or other suitable shape, and does not need to have the same shape as the housing cover 320 and / or the base plate 330.

[0060] In some deformation forms, the analyte monitoring device 110 may directly provide user status, the status of the analyte monitoring device, and / or other appropriate information via a user interface (e.g., a display, an indicator light, etc. as described below) on the analyte monitoring device 110. Thus, in contrast to an analyte monitoring device that can transmit information separately to a separate peripheral device (e.g., a mobile phone, etc.) alone and then transmit that information to the user, in some deformation forms, such information may be directly provided by the analyte monitoring device 110.

[0061] Accordingly, in some variations, the housing cover 320 may include a user interface, such as an interface that provides information visually, auditorily, and / or tactilely to provide information regarding the user state and / or the state of the analyte monitoring device and / or other suitable information. Examples of user states that may be communicated via the user interface include information representing an analyte measurement in the user (e.g., below a predetermined target analyte measurement threshold or range, within a predetermined target analyte measurement range, above a predetermined target analyte measurement threshold or range, an increase or decrease in analyte measurement over time, a rate of change of analyte measurement, other information regarding the trend of analyte measurement, other suitable warnings associated with the analyte measurement, etc.). Examples of the state of the analyte monitoring device that may be communicated via the user interface include the device operation mode (e.g., related to the warm-up state of the device, the analyte monitoring state, the battery power state such as low battery, etc.), the device error state (e.g., operation error, pressure-induced sensing attenuation, failure, failure mode, etc.), the device power state, the device life state (e.g., the end of the expected sensor life), the state of the connection between the device and the mobile computing device, etc.

[0062] In some variations, the user interface can be in a default enabled or "on" state at all times when at least the analyte monitoring device 110 is performing an analyte measurement or when the power of the analyte monitoring device 110 is on, thereby helping to ensure that the information is continuously available to the user. For example, user interface elements can communicate via a display or indicator light (e.g., as described below) not only to flag the user's attention and recommend corrective measures, but also to communicate when the user state and / or the state of the device is normal. Thus, in some variations, the user does not need to perform an operation to start a scan to know the current analyte measurement level, and such information can always be readily available to the user. However, in some variations, the user can perform an operation to temporarily disable the user interface (e.g., similar to a "snooze" button) for a predetermined time (e.g., 30 minutes, 1 hour, 2 hours, etc.) during which the user interface is automatically re-enabled or until a second operation is performed to re-enable the user interface.

[0063] In some variations, the user interface of the housing cover 320 can include a display configured to communicate information visually. The display can include, for example, an alphanumeric text (e.g., numbers, letters, etc.), symbols, and / or a display screen (e.g., an LCD screen, an OLED display, an electrophoretic display, an electrochromic display, etc.) configured to display appropriate graphics for communicating information to the user. For example, the display screen can include numerical information, text information, and / or graphics (e.g., slanted lines, arrows, etc.) of information such as the user state and / or the state of the analyte monitoring device. For example, the display screen can include a text or graphic representation of the analyte measurement level, trend, and / or recommendation (e.g., physical activity, reduction of food intake, etc.).

[0064] The display lights on the display may be lit in one or more various ways to communicate different types of information. For example, the display lights can be selectively lit or extinguished to convey information (e.g., lighting "on" indicates one state and lighting "off" indicates another state). The display lights may be lit in a selected color or intensity to convey information (e.g., lighting of a first color or intensity indicates a first state and lighting of a second color or intensity indicates a second state). The display lights may be lit in a selected time pattern to convey information (e.g., lighting of a first time pattern indicates a first state and lighting of a second time pattern indicates a second state). For example, the display lights may be selectively lit in one of a plurality of predetermined time patterns where the lighting frequency (e.g., repetitive lighting at high or low frequencies), regularity (e.g., periodic repetitive lighting vs. intermittent lighting), lighting duration "on" time, lighting duration "off" time, rate of change of lighting intensity, duty cycle (e.g., ratio of lighting "on" time to lighting "off" time), etc. are different, and each predetermined time pattern may indicate a respective state.

[0065] In some variations, the display can include a plurality of display lights that can be collectively lit in one or more predetermined lighting modes or sequences according to one or more predetermined spatial and / or time patterns. For example, in some variations, some or all of the display lights arranged on the display may be lit synchronously or in sequence to indicate a particular state. Thus, the selected subset of display lights (e.g., the spatial arrangement of the lit display lights) and / or the way they are lit (e.g., lighting order, lighting speed, etc.) can indicate a particular state. In some variations, to enhance the diversity of the color palette, multiple display lights may be lit simultaneously or in sequence. For example, in some variations, red, green, and blue LEDs can be rapidly lit in succession to create an impression of white light for the user.

[0066] In some variations, one or more of the above lighting modes can be combined in any suitable way (e.g., combinations of various colors, intensities, brightness, luminosities, contrasts, timings, positions, etc.) to convey information.

[0067] Figures 4A - 4E show aspects of the sensor assembly 350 of the analyte monitoring device 110 in perspective exploded view, side exploded view, distal perspective view, side view, and proximal perspective view, respectively.

[0068] The sensor assembly 350 includes micro - needle array components and electronic components for implementing the analyte detection and processing aspects of the micro - needle - array - based continuous analyte monitoring device 110 for the detection and measurement of analytes. In some variations, the sensor assembly 350 is a compact and thin laminate that is at least partially housed within an internal volume defined by a housing cover 320 and a base plate 330.

[0069] In some variations, the sensor assembly 350 includes a micro - needle array assembly 360 and an electronics assembly 370 that are connected to each other to implement the micro - needle array analyte detection and processing aspects further described herein. In some variations, the electronics assembly 370 includes a first printed circuit board (PCB) 450 to which electronic components are connected, and the micro - needle array assembly 360 includes a second printed circuit board (PCB) 420 to which the micro - needle array 140 is connected.

[0070] In some variations, the micro-needle array assembly 360 includes, in addition to the second PCB 420 and the micro-needle array 140, an epoxy skirt 410 and a second PCB connector 430. The micro-needle array 140 is coupled to the upper side (e.g., the outer-facing side or the distal side) of the second PCB 420 such that the individual micro-needles of the micro-needle array 140 are exposed, as described with reference to FIGS. 3A-3D. The second PCB connector 430 is coupled to the back side or the distal side of the second PCB 420 opposite the upper side. The second PCB connector 430 can be an electromechanical connector and can be communicatively coupled to the first PCB 450 via a first PCB connector 470 on the upper side (e.g., the outer-facing side or the distal side) of the first PCB 450 to enable signal communication between the second PCB 420 and the first PCB 450. For example, signals from the micro-needle array 140 can be communicated to the first PCB 450 via the second PCB 420, the second PCB connector 430, and the first PCB connector 470.

[0071] The second PCB 420 can partially determine the distance that the micro-needle array 140 projects from the backplate 330 of the housing. Thus, the height of the second PCB 420 can be selected to help ensure that the micro-needle array 140 is properly inserted into the user's skin. During micro-needle insertion, the first surface (e.g., the outer-facing surface) of the connection member 332 of the backplate 330 can function as a stop for micro-needle insertion. If the height of the second PCB 420 is low and its upper surface is in the same plane or substantially in the same plane as the first surface of the connection member 332, the connection member 332 can prevent the micro-needle array 140 from being fully inserted into the skin.

[0072] In some variations, other components (e.g., electronic components such as sensors or other components) can also be connected to the second PCB 420. For example, the second PCB 420 can be sized and shaped to accommodate electronic components on its upper side or back side.

[0073] In some variations, the epoxy skirt 410 is deposited along the edge (e.g., outer perimeter) of the micro-needle array 140, as shown in FIGS. 3B and 3C, to provide a secure fit of the micro-needle array 140 into the aperture 334 formed in the connection member 332 of the base plate 330, and / or to blunt sharp edges along the micro-needle array 140. For example, the epoxy skirt 410 may occupy portions of the aperture 334 not filled by the micro-needle array 140, and / or portions of cavities defined within the base plate 330 not filled by the second PCB 420. The epoxy skirt 410 may also provide a transition from the edge of the micro-needle array 140 to the edge of the second PCB 420. In some variations, the epoxy skirt 410 may be replaced or supplemented by a gasket (e.g., a rubber gasket) or the like.

[0074] The electronic device assembly 370 having the first PCB 450 includes a battery 460 coupled to the back side of the first PCB 450, opposite the upper side to which the first PCB connector 470 is coupled. In some variations, the battery 460 may be coupled to the upper side of the first PCB 450 and / or in other arrangements. Further details of the electronic device assembly 370 are described with reference to FIG. 5.

[0075] FIGS. 4F - 4H show aspects of an alternative variation of the sensor assembly 350 of the analyte monitoring device 110. A perspective exploded view, a side exploded view, and a side view of the sensor assembly 350 are provided in FIGS. 4F - 4H, respectively.

[0076] As shown, the sensor assembly 350 incorporates an intermediate PCB 425, which is an additional PCB component. In some variations, the intermediate PCB 425 is part of the micro - needle array assembly 360 and is disposed between and connected to the second PCB 420 and the micro - needle array 140. The intermediate PCB 425 may be added to increase the height of the micro - needle array assembly 360, such that the micro - needle array 140 extends a greater distance from the base plate 330, which may assist in the insertion of the micro - needle array 140 into the user's skin. The micro - needle array 140 is coupled to the upper side (e.g., the side facing outward) of the intermediate PCB 425 such that the individual micro - needles of the micro - needle array 140 are exposed, as described with reference to FIGS. 3A - 3D. The second PCB 420 is coupled to the back side of the intermediate PCB 425 opposite the upper side, and the second PCB connector 430 is coupled to the back side of the second PCB 420 opposite the upper side. An epoxy skirt 410 (which may be replaced or supplemented by an equivalent gasket) provides a transition from the edge of the micro - needle array 140 to the edge of the intermediate PCB 425.

[0077] The intermediate PCB 425 having the second PCB 420 partially determines the distance that the micro - needle array 140 projects through the aperture 334 of the backplate 330. The incorporation of the intermediate PCB 425 provides an additional height that helps ensure that the micro - needle array 140 is properly inserted into the user's skin. In some variations, the upper side (e.g., the side facing outward) of the intermediate PCB 425 extends out through the aperture 334, such that the first surface (e.g., the exposed upper surface) of the connection member 332 surrounding the aperture 334 does not prevent the micro - needle array from being fully inserted into the skin. In some variations, the upper side (e.g., the side facing outward) of the intermediate PCB 425 does not extend out from the aperture 334, but the increased height (by incorporating the intermediate PCB 425) ensures that the micro - needle array 140 projects a sufficient distance from the housing's backplate 330.

[0078] FIG. 5 shows a block diagram representation of the sensor assembly 350 of the analyte monitoring device 110. The sensor assembly 350 includes aspects of the micro-needle array assembly 360 and the electronics assembly 370, which may include aspects of the electronics system 120 shown and described with reference to FIG. 2A.

[0079] The sensor assembly 350 includes a first PCB 450 for the electronics assembly 370 and a second PCB 420 (and optionally an intermediate PCB 425) for the micro-needle array assembly 360. The first PCB 450 and the second PCB 420 may be connected, thereby establishing a connection between the micro-needle array assembly 360 and the electronics assembly 370 by means of a connector. For example, a second PCB connector 430 on the back side of the second PCB 420 connects to a first PCB connector 470 on the upper side of the first PCB 450.

[0080] The second PCB connector 430 and the first PCB connector 470 may be electromechanical connectors that provide a communication coupling between the second PCB 420 and the first PCB 450 and enable signal communication between the second PCB 420 and the first PCB 450. For example, signals from the micro-needle array 140 may be communicated to the first PCB 450 via the second PCB 420, the second PCB connector 430, and the first PCB connector 470.

[0081] The first PCB 450 may include various electronic components for receiving and processing the electrochemical signals received from the micro-needle array 140, and some of the electronic components may be included for additional functions. As shown in FIG. 5, the first PCB 450 may include an analog front end 502, a thermistor 504, a real-time clock 506, an ambient light sensor 508, a microcontroller 510 (or a controller), a motion sensor 512, a communication controller 514, an antenna 516, a battery 460, a voltage regulator 522, and a boost circuit 520 coupled thereto. In some variations, the second PCB 420 or the intermediate PCB 425 may include a thermistor 504 in addition to the micro-needle array 140 and the second PCB connector 430. In some variations, the thermistor 504 is arranged to minimize the distance to the user's skin. In some variations, the thermistor 504 is not included and the temperature measurement may be obtained from a temperature sensor incorporated in the analog front end 502. In some variations, fewer, additional, and / or alternative components may be included in the sensor assembly 350 as further described herein.

[0082] The analog front end 502 is part of the sensor assembly 350 of the analyte monitoring device 110 (e.g., part of the electronic device assembly 370). The analog front end 502 can include a sensor circuit (e.g., the sensor circuit 124 as shown in FIG. 2A) that converts an analog current measurement into a digital value that can be processed by the microcontroller 510. The analog front end 502 can include, for example, a programmable analog front end suitable for use with an electrochemical sensor. In some variations, the analog front end 502 can be an ultra-low power programmable analog front end for use with an electrochemical sensor. In some variations, the analog front end 502 can be a high-precision, impedance, and electrochemical front end. In some variations, the analog front end 502 can be a configurable analog front end potentiostat for low-power chemical sensing applications. The analog front end 502 can provide a bias and a complete measurement path that includes an analog-to-digital converter (ADC). The ultra-low power can enable the continuous energization of the microneedle array 140 to maintain accuracy and fast response.

[0083] In some variations, the analog front end 502 can be compatible with both two- and three-terminal electrochemical sensors, for example, to enable both DC current measurement, AC current measurement, and electrochemical impedance spectroscopy (EIS) measurement capabilities. Further, the analog front end 502 includes an internal temperature sensor and a programmable voltage reference, supports external temperature monitoring, provides an external reference source, and can integrate voltage monitoring of the bias voltage and supply voltage for safety and compliance.

[0084] In some variations, the analog front end 502 can include a multi-channel potentiostat for multiplexing sensor inputs and processing multiple signal channels. For example, the analog front end can include a multi-channel potentiostat as described in U.S. Patent No. 9,933,387, which is hereby incorporated by reference in its entirety.

[0085] In some variations, the analog front end 502 and the peripheral electronics can be integrated into an application specific integrated circuit (ASIC). In some variations, this integrated solution can include the microcontroller 510 described below.

[0086] In some variations, the sensor assembly 350 of the analyte monitoring device 110 may include at least one microcontroller 510 (e.g., the controller 122 shown in FIG. 2A) incorporated into the electronics assembly 370. The microcontroller 510 can include, for example, a processor with integrated flash memory. In some variations, the microcontroller 510 in the analyte monitoring device 110 can be configured to perform an analysis that correlates the sensor signal to an analyte measurement (e.g., a glucose measurement). For example, the microcontroller 510 can execute a programmed routine in the firmware to interpret a digital signal (e.g., from the analog front end 502), perform any relevant algorithms and / or other analyses, and route the processed data between a communication module (e.g., the communication module 126 shown in FIG. 2A). By keeping the analysis on the analyte monitoring device 110, for example, the analyte monitoring device 110 can broadcast the analyte measurement in parallel to multiple devices (e.g., mobile computing devices such as smartphones or smartwatches, treatment delivery systems such as insulin pens or pumps, etc.) while ensuring that each connected device has the same information.

[0087] In some variations, the microcontroller 510 may be configured to start and / or stop the analyte monitoring device 110 in response to one or more detected conditions or states of the environment (e.g., the area surrounding the analyte monitoring device 110) or one or more components of the analyte monitoring device 110. For example, the microcontroller 510 may be configured to turn on the power of the analyte monitoring device 110 in response to one or more conditions such as the insertion of the microneedle array 140 into the skin, the removal of the analyte monitoring device 110 from the applicator device, the transition of the analyte monitoring device 110 from a non-functional state to a functional state, and a command from an external device, as further described herein. The microcontroller 510 may be configured to turn on the power of the analyte monitoring device 110 in response to the determination of a valid power-on event. Based on the type of the valid power-on event, the microcontroller 510 may cause the analyte monitoring device 110 to transition to a corresponding operating mode. In some variations, the microcontroller 510 may be configured to determine the source of the power-on event and cause the analyte monitoring device 110 to transition to an operating mode corresponding to the source of the power-on event. Additional details regarding power-on are further described below.-

[0088] In some variations, the microcontroller 510 can utilize 8-bit, 16-bit, 32-bit, or 64-bit data structures. Suitable microcontroller architectures include reduced instruction set computer (RISC) architectures or complex instruction set computer (CISC) architectures, and the flash memory may be embedded in the microcontroller 510 for suitable data storage or may be external. In some variations, the microcontroller 510 may be a single-core microcontroller, and in some variations, the microcontroller 510 may be a multi-core (e.g., dual-core) microcontroller that can enable a flexible architecture for optimizing power and / or performance within the analyte monitoring device 110. For example, the cores within the microcontroller 510 can include the same or different architectures. For example, in one exemplary variation, the microcontroller 510 may be a dual-core microcontroller that includes a first core having a high-performance and high-power architecture and a second core having a low-performance and low-power architecture. The first core can function as the "main force" in that it can be used to process higher-performance functions (e.g., sensor measurements, algorithm calculations, etc.), and the second core can be used to execute lower-performance functions (e.g., background routines, data transmissions, etc.). Thus, the different cores of the microcontroller 510 can operate at different duty cycles optimized for their respective functions (e.g., the second core for lower-performance functions can operate at a higher duty cycle), thereby improving overall power efficiency. In some variations, the microcontroller 510 may include embedded analog circuitry, such as for interfacing with additional sensors and / or the micro-needle array 140. In some variations, the microcontroller 510 may be configured to operate using a power supply of 0.8V to 5V, such as a 1.2V to 3V power supply.

[0089] In some variations, the sensor assembly 350 of the analyte monitoring device 110 may include at least one communication module, such as a wireless communication module for communicating with one or more devices (e.g., communication module 126 as shown in FIG. 2A). For example, the communication module may include a wireless transceiver integrated with the microcontroller 510. However, the electronic device assembly 370 may alternatively or additionally include a communication module separate from the microcontroller 510. In some variations, the communication module can communicate via a wireless network (e.g., via Bluetooth®, NFC, WiFi, RFID, Thread, 6LoWPAN, LoRa, or any type of data transmission not connected by a cable). For example, the devices can communicate directly with each other in a pairwise connection (a 1:1 relationship, e.g., unicast), or a hub-spoke connection or a broadcast connection (a "one-to-many" or 1:m relationship, e.g., multicast). As another example, the devices can communicate with each other through a mesh networking connection such as Bluetooth® mesh networking (e.g., a "many-to-many", m:m relationship, or ad hoc).Wireless communication can use any of a plurality of communication standards, protocols, and technologies, including but not limited to Global System for Mobile Communications (GSM (registered trademark)), Enhanced Data GSM Environment (EDGE), high-speed downlink packet access (HSDPA), high-speed uplink packet access (HSUPA), Evolution, Data-Only (EV-DO), HSPA, HSPA+, Dual-Cell HSPA (DC-HSPDA), long term evolution (LTE), near field communication (NFC), wideband code division multiple access (W-CDMA), code division multiple access (CDMA), time division multiple access (TDMA), Bluetooth (registered trademark), Wireless Fidelity (WiFi) (e.g., IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11n, etc.), or any other suitable communication protocol. In the deployment of some wireless networks, it may be possible to combine networks from multiple mobile wireless networks or use a mixture of mobile wireless, Wi-Fi, and satellite communications. In an exemplary variant, the communication module can include a wireless transceiver integrated with a microcontroller and including a Bluetooth Low Energy compatible radio compliant with the Bluetooth Special Interest Group 5.0 specification.

[0090] The communication module may further include one or more antennas (e.g., antenna 128 shown in FIG. 2A) or may be coupled to one or more antennas. For example, the sensor assembly 350 can include a chip antenna mounted on the first PCB 450 or an antenna mounted directly on the first PCB 450, thereby providing a better range while reducing cost and complexity. In some variations, as shown in FIG. 5, the communication controller 514 may be part of the sensor assembly 350 on the first PCB 450 and may be coupled to the antenna 516 for wireless communication according to various wireless protocols as described above. In a variation, the communication controller 514 is an NFC tag IC or an NFC module. In some variations, instead of occupying space on the first PCB 450, the antenna can be included within the housing, such as in the lower or upper regions of the housing cover 320, or etched on the housing. For example, a portion of the housing cover 320 may be metallized, a metal may be deposited to form the antenna, and a contact between the metal and the first PCB 450 may be incorporated. In other variations, a flexible PCB may be incorporated for the antenna and may be fitted, for example, within the housing cover 320, and a contact between the flexible PCB and the main PCB may be incorporated. By incorporating the antenna in a separate space from the first PCB 450, additional space becomes available on the first PCB 450, and performance improvements can be achieved by optimizing the placement of the antenna (e.g., at or near the point closest to the housing cover 320).

[0091] In some variations, the remote device can enter and exit the range of the communication controller 514 (or other communication module) for connection and reconnection, such that the user can seamlessly connect and transfer information between devices (e.g., between the analyte monitoring device 110 and one or more remote devices). In some variations, the microcontroller 510 on the analyte monitoring device 110 can have a unique serial number that enables tracking of a particular analyte monitoring device 110 during manufacture and / or in-field use.

[0092] As described above, in some variations, the analyte monitoring device 110 can include one or more sensors in addition to the microneedle array 140. For example, the analyte monitoring device 110 can include one or more temperature sensors configured to measure the temperature of the skin and can be used to enable temperature compensation of the microneedle array 140. For example, in some variations, a thermistor 504 (or other temperature sensor such as a resistance temperature detector, semiconductor junction, bimetal sensor, and thermopile sensor) can be coupled to the first PCB 450 or the second PCB 420. The thermistor 504 can be disposed near a skin-facing or outward-facing side of the sensor assembly, such as on the second PCB 420 or on an upper side of the first PCB 450 (e.g., near or adjacent to the backplate 330). The backplate 330 can be of an appropriate thickness to reduce thermal resistance and improve heat transfer and measurement accuracy.

[0093] Integrating a sensor into the sensor assembly 350 can enable dynamic adjustment of the light level of an indicator light, such as a light-emitting diode (LED) 518, help compensate for ambient light conditions, and save power. The ambient light sensor 508 can be coupled to the first PCB 450 in some variations to sense the level of ambient light in the surrounding environment of the analyte monitoring device 110. Additional details regarding the use of the ambient light sensor 508 are provided below.

[0094] LED 518 may be coupled to the first PCB 450 of the sensor assembly 350 as part of the electronic device assembly 370. LED 518 may be controlled in one or more predetermined lighting patterns or modes to communicate different states and / or other appropriate information. The indicator light may be controlled to light up in multiple colors (e.g., red, orange, yellow, green, blue, and / or purple, etc.) or only one color. For example, the indicator light can include a multicolor LED. As another example, the indicator light may include a transparent or translucent material (e.g., acrylic) disposed over one or more light sources of different colors (e.g., LEDs) such that the light sources of different colors can be selectively activated to light up the indicator light in the selected color. The activation of the light sources can be performed simultaneously or in sequence. The indicator light can have any suitable form (e.g., protruding from the housing body, on the same plane, recessed, etc.) and / or shape (e.g., circular or other polygons, ring, elongated strip, etc.). In some variations, the indicator light may have the size and / or shape of a pinhole that emits light of the same intensity as a larger light source, but requires significantly less power, which helps to conserve the power consumption of the analyte monitoring device 110.

[0095] Although an LED is shown in FIG. 5, in some variations, other types of indicator lights may be incorporated into the sensor assembly 350. For example, the indicator light may include an LED, OLED, laser, electroluminescent material, or other suitable light source or waveguide. In some variations, instead of including an LED or an indicator light, the dome surface may be a liquid crystal display (LCD) or an E-Ink display.

[0096] In some variations, additional sensors may be incorporated into the sensor assembly 350. For example, a motion sensor 512 (as will be described in more detail below) may be incorporated into the electronic device assembly 370 and coupled to the first PCB 450. The motion sensor 512 may be used to further determine an appropriate period for the analyte monitoring device 110 to transition to a power-saving mode or a reduced-power state. For example, by detecting darkness via the ambient light sensor 508 and detecting no movement of the analyte monitoring device 110 via the motion sensor 512, it can be indicated that the wearer of the analyte monitoring device 110 is sleeping or in a relaxed state, which can trigger the analyte monitoring device 110 to transition to a power-saving mode or a reduced-power state. In some variations, the motion sensor 512 may be used to track the movement of the user of the analyte monitoring device 110 for other purposes. The motion sensor 512 can comprise, for example, an accelerometer, a gyroscope, and / or an inertial measurement unit for capturing values such as position, displacement, trajectory, velocity, acceleration, and / or the orientation of the device. For example, such measurements can be used to infer the wearer's physical activity (e.g., steps, intense exercise) over a finite period. In some variations, the motion sensor 512 can be used to enable detection of wearer interactions with the analyte monitoring device 110 such as touch or tap. For example, touch or tap detection can be used to silence or snooze notifications, warnings, and alarms, control a wirelessly connected mobile computing device, or activate and / or deactivate a user interface on the analyte monitoring device 110 (e.g., an embedded display or an indicator light such as an LED 518). The touch or tap may be performed in a defined sequence and / or for a predetermined period (e.g., at least 3 seconds, at least 5 seconds) to trigger a specific action (e.g., deactivating and / or activating a display or an indicator light).In some variations, the analyte monitoring device 110 may transition to a power-saving mode when restricted movement or activity (e.g., no significant acceleration) is detected for at least a predetermined period (e.g., 15 minutes, 30 minutes, 45 minutes, 1 hour, or other suitable time) as measured by the motion sensor 512 and / or other sensors.

[0097] In some variations, the analyte monitoring device 110 may include at least one real-time clock (RTC) 506. For example, the real-time clock 506 may be part of the electronics assembly 370 coupled to the first PCB 450. In some variations, the real-time clock 506 has a crystal oscillator or the like embedded therein to maintain accurate tracking of time. The real-time clock 506 may be used to track the absolute time (e.g., Coordinated Universal Time, UTC, or local time) when the analyte monitoring device 110 is stored or in use. In some variations, synchronization to absolute time may be performed after the manufacture of the analyte monitoring device 110. During operation, the real-time clock 506 may drive and / or adjust the internal clock of the microcontroller 510 to ensure that the microcontroller 510, which may have a lower timing accuracy than the real-time clock 506, is properly tracking time by outputting a clocking signal to the microcontroller 510. In some variations, the clocking signal from the real-time clock 506 to the microcontroller 510 is a constant signal. In some variations, the clocking signal is transmitted periodically at predetermined intervals.

[0098] The real-time clock 506 is used to timestamp analyte measurements (e.g., glucose measurements) during the operation of the analyte monitoring device 110 to create a time series dataset that is communicated to a connected peripheral device (e.g., a mobile computing device), cloud storage, or other suitable data storage device for later review by, for example, a user (e.g., the wearer of the analyte monitoring device), a support network, a healthcare provider, etc. In some variations, the microcontroller 510 performs the timestamping operation.

[0099] As shown in FIG. 2A, the analyte monitoring device can include one or more power sources 130 configured to supply power to other components. For example, the analyte monitoring device 110 may include a battery 460. The battery 460 can be any suitable type of battery capable of supplying power to various components of the sensor assembly 350. The battery 460 can be a silver oxide battery having a high energy density and being more environmentally friendly than a lithium battery. In some variations, a primary (e.g., non-rechargeable) battery can be used. Further, in some variations, a secondary (e.g., rechargeable) battery can be used. However, any suitable power source including a lithium-based battery can be used.

[0100] In some variations, as further described below, the battery 460 can be coupled to a boost circuit 520. The boost circuit 520 can be part of the electronics assembly 370 coupled to the first PCB 450. The boost circuit 520 can be incorporated to provide an appropriate power level to specific electronic components. For example, the boost circuit 520 can boost or increase the voltage provided by the battery 460 to provide sufficient power to one or more of the components of the sensor assembly 350, as further described herein. In some variations, a voltage regulator 522 can be coupled to the output of the boost circuit 520 to reduce the noise generated by the boost circuit 520.

[0101] In some variations, the analyte monitoring device 110 may be paired with at least one peripheral device, such that the peripheral device receives data broadcast from the analyte monitoring device 110 or otherwise transmitted, including measurement data. Suitable peripheral devices include, for example, mobile computing devices (e.g., smartphones, smartwatches) that may be running a mobile application.

[0102] As described above, pairing can be accomplished by a suitable wireless communication module (e.g., implementing NFC and / or Bluetooth®). In some variations, pairing can occur after the analyte monitoring device 110 has been applied and inserted into the user's skin (e.g., after the analyte monitoring device 110 has been activated). Pairing may also occur before the analyte monitoring device 110 is applied and inserted into the user's skin.

[0103] Accordingly, the paired mobile or other device can receive data broadcast or transmitted from the analyte monitoring device 110. The peripheral device 110 can display, store, and / or transmit the measurement data to the user and / or healthcare provider and / or support network. Further, in some variations, the paired mobile or wearable device may perform algorithmic processing on the data to improve signal fidelity, accuracy, and / or calibration, etc. In some variations, the measurement data and / or other user information may alternatively or additionally be communicated and / or stored via a network (e.g., a cloud network).

[0104] As an example, in some variations, a mobile computing device or other computing device (e.g., smartphone, smartwatch, tablet, etc.) may be configured to execute a mobile application that provides an interface for displaying an estimated glucose value, trend information, historical data, and the like. The following description specifically refers to glucose as the target analyte, but the features and processes described below with respect to glucose may equally apply to applications related to other types of analytes.

[0105] In some variations, the mobile application can use the wireless communication framework of the mobile computing device to scan for the analyte monitoring device 110. The analyte monitoring device 110 can be powered on or initialized when applied to the skin, and the analyte monitoring device 110 can initiate an alert process. The mobile application can then connect to the analyte monitoring device 110 and initiate priming of the microneedle array 140 for measurement. If the mobile application detects multiple analyte monitoring devices, the mobile application may detect the analyte monitoring device 110 closest to itself, request confirmation from the user (e.g., via a user interface on the mobile device) to resolve ambiguity, and / or request confirmation via a physical interaction with the analyte monitoring device 110 intended for use (e.g., a tap or other predetermined action on the analyte monitoring device 110 by the user). In some variations, the mobile application may also be able to connect to multiple analyte monitoring devices simultaneously. This may be useful, for example, for replacing a sensor that is approaching the end of its life.

[0106] In some variations, the Bluetooth (R) Low Energy (TM) (BLE) protocol may be used for the connection. For example, the sensor implements a custom BLE peripheral profile for the analyte monitoring system. Data can be exchanged after establishing a standard secure BLE connection between the analyte monitoring device and a smartphone, smartwatch, or tablet running a mobile application. The BLE connection may be maintained permanently over the life of the sensor. If the connection is lost for any reason (e.g., weak signal), the analyte monitoring device may restart its own advertisement, and the mobile application may re - establish the connection at the earliest opportunity (e.g., when in range / based on physical proximity).

[0107] In some variations, one or more additional security layers may be implemented on top of the BLE connection to ensure authorized access consisting of a combination of one or more techniques such as passcode protection, shared secrets, encryption, and multi - factor authentication.

[0108] The mobile application can guide the user by initiating a new analyte monitoring device. Once this process is complete, the mobile application is not required for the analyte monitoring device 110 to operate and record measurements. In some variations, a smart insulin delivery device connected to the analyte monitoring device 110 can be authorized from the mobile application to receive glucose readings directly from the sensor. In some variations, a secondary display device such as a smartwatch can be permitted from the mobile application to receive glucose readings directly from the sensor.

[0109] Furthermore, in some variations, the mobile application can additionally or alternatively help to calibrate the analyte monitoring device 110. For example, the analyte monitoring device 110 can indicate a calibration requirement to the mobile application, and the mobile application can request calibration input from the user to calibrate the sensor.

[0110] FIG. 6 shows a system block diagram of a power architecture 600 of a sensor assembly 350 of an analyte monitoring device 110 according to some embodiments. The power architecture 600 defines how power can be distributed through the sensor assembly 350. The power architecture 600 executes a power management process to assist in providing for multiple days of use of the analyte monitoring device 110. For example, in some variations that utilize the power architecture 600 implementing the power management aspects described herein, the analyte monitoring device 110 may operate continuously for up to 10 days (e.g., as long as the battery 460 lasts). In some variations, the analyte monitoring device 110 may operate continuously for up to 5, 6, 7, 8, or 9 days. In some variations, depending on the power source and the components of the sensor assembly 350, the analyte monitoring device 110 may operate continuously for more than 10 days.

[0111] As shown in FIG. 6, the battery 460 provides power to the real-time clock 506 and the power connection circuit 620 and may be coupled to the first PCB 450 in some variations. The power connection circuit 620 connects the battery 460 to additional electronic components of the sensor assembly 350, enabling the battery 460 to supply power to the additional electronic components. For example, the power connection circuit 620 includes switches that connect the battery 460 to the boost circuit 520, the microcontroller 510, and the peripheral power switch 630. In other variations, the power connection circuit 620 may connect the battery 460 to fewer, additional, or alternative components. By incorporating the power connection circuit 620 into the power architecture 600 of the sensor assembly 350, the power from the battery 460 to the additional components is controlled. For example, the power connection circuit 620 may maintain an open position until the occurrence of a trigger event (e.g., the switch is open and thus the connection between the battery 460 and the boost circuit 520, the microcontroller 510, and the peripheral power switch 630 is not established). The trigger event sends a signal to the power connection circuit 620 to establish a connection between the battery 460 and the additional electronic components, thereby ensuring that the battery 460 is not unnecessarily depleted. The trigger event may be, for example, an event indicating the start of use of the analyte monitoring device 110 for the active detection and measurement of an analyte.

[0112] In some variations, the trigger event may be the detection of light. For example, the analyte monitoring device 110 may be maintained in a dark or darkened environment until the user is ready to apply and use the analyte monitoring device 110. When the analyte monitoring device 110 is removed from the dark or darkened environment, light can be detected by the analyte monitoring device 110 being removed from the dark or darkened environment. For example, the analyte monitoring device 110 may be housed in a container that provides a dark or darkened environment for storage. The container may be, for example, a package unit or an applicator device. When the analyte monitoring device 110 is removed from the container (e.g., dispensed from a package unit or applied to the user by an applicator device) or the container is at least partially opened, light (e.g., a trigger event) from the new environment can be detected. In some variations, a seal, sticker, protective cover, etc. may be applied to one or more portions of the analyte monitoring device 110. Removing the seal, sticker, or protective cover exposes the analyte monitoring device 110 to light and causes a trigger event.

[0113] The power connection circuit 620 may receive a signal or instruction indicating a trigger event (e.g., from another component). As described, the trigger event may be the detection of light (e.g., ambient light surrounding the sensor assembly 350). For example, in some variations, a light detection circuit 610 is incorporated to detect ambient light. The light detection circuit 610 may be a phototransistor that responds to light. When light impinges on the phototransistor, the phototransistor is triggered and sends a signal to the power connection circuit 620. Thus, in response to the detection of light (e.g., a trigger event), the light detection circuit 610 sends a signal to the power connection circuit 620, and the power connection circuit 620 responds by closing a switch, resulting in a connection being established between the battery 460 and the boost circuit 520, the microcontroller 510, and the peripheral power switch 630. The battery 460 then begins to discharge and starts supplying power to the boost circuit 520, the microcontroller 510, and the peripheral power switch 630. As described, in some variations, the power connection circuit 620 may provide a connection between the battery 460 and fewer, additional, or alternative electronic components.

[0114] In some variations, the photodetection circuit 610 is not connected until the micro-needle array assembly 360 is connected to the electronic device assembly 370. For example, the photodetection circuit 610 may be coupled to the first PCB 450 and may have signal lines routed through the second PCB 420. When the first PCB 450 and the second PCB 420 are not connected (e.g., the micro-needle array assembly 360 is not connected to the electronic device assembly 370), the photodetection circuit 610 is disabled because the signal lines routed through the second PCB 420 are open, and as a result, the circuit of the electronic device assembly 370 is disconnected. In this disconnected state, the power connection circuit 620 is not connected to the photodetection circuit 610, and the switch of the power connection circuit 620 remains open. When the first PCB 450 and the second PCB 420 are connected, the signal sent from the photodetection circuit 610 via the second PCB 420 is completed, and the photodetection circuit 610 becomes operable. In this connected state, the photodetection circuit 610 is connected to the power connection circuit 620, and the power connection circuit 620 can respond to signals or commands from the photodetection circuit 610.

[0115] Accordingly, the micro-needle array assembly 360 causes the photodetection circuit 610 to be connected to the power connection circuit 620 of the electronic device assembly 370. This ensures that the battery 460 cannot be depleted (e.g., by discharging to electronic components connected to the power connection circuit 620 through the power connection circuit 620) until the second PCB 420 is connected to the first PCB 450 via the second PCB connector 430 and the first PCB connector 470. In some variations, this eliminates or reduces battery depletion that can occur during certain stages of manufacturing (e.g., until the micro-needle array assembly 360 is connected to the electronic device assembly 370).

[0116] The power connection circuit 620 may further include a latch circuit that functions to maintain the connection between the battery 460 and the boost circuit 520, the microcontroller 510, and the peripheral power switch 630 (e.g., keep the switch closed) after the switch within the power connection circuit 620 is moved to the closed position. The latch circuit ensures that the optical detection circuit 610 does not interfere with the power connection circuit 620 after the trigger event. In some variations, the power connection circuit 620 may include an ideal diode to control one-way charging and prevent reverse power feeding of the battery 460.

[0117] By incorporating the power connection circuit 620 into the power architecture 600 of the sensor assembly 350, the power from the battery 460 to additional components is controlled. For example, the power connection circuit 620 may maintain an open position until the trigger event occurs (e.g., the switch is open and thus the connection between the battery 460 and the boost circuit 520, the microcontroller 510, and the peripheral power switch 630 is not established). The trigger event sends a signal to the power connection circuit 620 to establish the connection between the battery 460 and the additional electronic components, thereby ensuring that the battery 460 is not unnecessarily consumed. The trigger event may be, for example, an event indicating the start of use of the analyte monitoring device 110 for the active detection and measurement of an analyte.

[0118] As shown in FIG. 6 and as described above, the microcontroller 510 is powered by the battery 460 via the power connection circuit 620. The microcontroller 510 is coupled to the boost circuit 520 and the peripheral power switch 630 via respective enable pins. In response to the microcontroller 510 booting or starting a boot sequence, the main power latch within the microcontroller 510 is asserted. The microcontroller 510 can remove and / or apply power to the peripheral units via the peripheral power switch 630, as further described herein. The microcontroller 510 may remove and / or apply power to the boost circuit 520. In some variations, for example, the microcontroller 510 may remove and / or apply power to the LED 518.

[0119] As shown in FIG. 6, the boost circuit 520 supplies power to the LED 518 and the analog front end 502. In some variations, the LED 518 and the analog front end 502 require a stable voltage that exceeds the voltage of the battery 460 throughout the operation. In some variations, the voltage of the battery 460 decreases over time as its capacity is used. For example, the battery 460 may be a 3V battery, but may drop to a lower level as its capacity is used. The voltage required by the LED 518 and / or the analog front end 502 may exceed the maximum voltage of the battery 460, or the voltage required by the LED 518 and / or the analog front end may exceed the voltage value of the battery 460 as its capacity is used. The boost circuit 520 is incorporated in some variations to provide a stable voltage required by the LED 518 and the analog front end 502. In some variations, the boost circuit 520 boosts the voltage to other or additional components of the sensor assembly 350. In some variations, as shown in FIG. 6, the voltage regulator 522 is connected between the boost circuit 520 and the analog front end 502 to reduce the noise generated by the boost circuit 520 and provide a more stable signal to the analog front end 502.

[0120] In some variations, the LED 518 may require a stable voltage higher than the voltage of the battery 460, and the boost circuit 520 operates to boost the battery voltage to the level required by the LED 518. In some variations, by applying a voltage higher than required to the LED 518, the LED 518 can output illumination having consistent brightness throughout the use of the analyte monitoring device 110. As described herein, the battery voltage can drift downward during the life of the battery 460 when the battery 460 is discharging. In some variations, the voltage required by the analog front end 502 can be higher than the voltage of the battery 460 because the battery voltage drifts downward. To compensate for this difference, the boost circuit 520 operates to boost the battery voltage to the level required by the analog front end 502. In some variations, the boost circuit 520 provides the same voltage to the LED 518 and the analog front end 502. In other variations, different, customized voltages are provided to the LED 518 and the analog front end 502.

[0121] As shown in FIG. 6 and as described above, the peripheral power switch 630 is powered by the battery 460 via the power connection circuit 620. When the peripheral power switch 630 is connected to the battery 460 via the power connection circuit 620, it supplies power to various peripheral devices. For example, the peripheral power switch 630 supplies power to the motion sensor 512, the ambient light sensor 508, the thermistor 504, other sensors 632, and the output device 634 (e.g., a linear resonant actuator (LRA) and / or an eccentric rotating mass (ERM) for tactile output, a speaker). In some variations, the peripheral power switch 630 can disable the communication controller 514.

[0122] In some variations, the microcontroller 510 may determine that the battery 460 is approaching the end of its life. For example, the microcontroller 510 may determine that the voltage level of the battery 460 is low and / or that the expected end of life is approaching. The end-of-life determination may be made through measurement of the voltage of the battery 460 under load. Over time, as the capacity of the battery 460 decreases, the voltage decreases, which can be used as an indicator of the life of the battery 460. In some variations, in response to the determination that the voltage level of the battery 460 is low and / or that the expected end-of-life is approaching, the microcontroller 510 may enter a reduced-power state. In the reduced-power state, the microcontroller 510 may cut off power to one or more electronic components. In some variations, the microcontroller 510 may cut off power to one or more electronic components (e.g., motion sensor 512, ambient light sensor 508, other sensors 632, output device 634, LED 518) not involved in analyte detection and measurement. In some variations, in the reduced-power state, the microcontroller 510 may adjust the use of one or more electronic components. For example, the microcontroller may adjust the brightness of the LED 518 and / or the illumination sequence of the LED 518 so that the LED 518 emits less light and / or is illuminated for a shorter period or at a lower frequency, thereby saving power. For example, in the reduced-power state, the brightness of the LED 518 may be adjusted so that the LED 518 is dimmed by about 50% compared to when it is operating normally. In some variations, other levels of brightness (e.g., about 20% to about 80% of the normal operating brightness) may be used. The illumination sequence of the LED 518 may be adjusted so that the LED 518 is illuminated less frequently than when it is operating normally. For example, in the reduced-power state, the time between illuminations of the LED 518 can be increased by about 1 to about 10 times that of normal operation.

[0123] As shown in FIG. 6, the power architecture 600 of the sensor assembly 350 of the analyte monitoring device 110 may include an ambient power generation module 640. The power from the ambient power generation module 640 may be used to download data when the battery 460 reaches the end of its life or before the battery 460 is connected to the microcontroller 510. In some variations, data (e.g., sensor data and / or operation data related to the operation of the analyte monitoring device 110) may be stored on the microcontroller 510 (e.g., the memory of the microcontroller 510) and transmitted to the communication controller 514. For example, the data may be transmitted in chunks via a link (e.g., an NFC link) between the microcontroller 510 and the communication controller 514. Then, using the ambient power generation module 640, the data may be downloaded to an external device (e.g., the user's device, a remote server) using, for example, an NFC reader. This solution ensures that data (e.g., sensor data and / or operation data related to the operation of the analyte monitoring device 110) is not lost even if the battery 460 is depleted. In some alternative variations, the ambient power generation module 640 (e.g., when the battery 460 is depleted or before the connection of the battery 460) may be used as a backup, alternative, or temporary power source instead of the battery 460. The ambient power generation module 640 can supply power to the boost circuit 520, the microcontroller 510, and the peripheral power switch 630 to continue the operation of the analyte monitoring device 110. In some variations, the ambient power generation module 640 can supply power to all components of the sensor assembly 350. In some variations, the real-time clock 506 is not powered. In some variations where a secondary battery is incorporated, the ambient power generation module 640 may be used to recharge a primary battery (e.g., the battery 460) during the time the secondary battery can be used. When the battery 460 is recharged, the ambient power generation module 640 can be used to recharge the secondary battery.

[0124] FIG. 7 shows an exemplary process flow chart 700 implemented by a power architecture 600 of a sensor assembly 350 of an analyte monitoring device 110.

[0125] At 702, the micro-needle array assembly 360 connects the light detection circuit 610 to the power connection circuit 620. For example, in some variations, the light detection circuit 610 is not connected to the electronic device assembly 370 until the micro-needle array assembly 360 is connected to the electronic device assembly 370. This ensures, for example, that the battery 460 cannot be unnecessarily or inadvertently depleted during certain stages of manufacturing (e.g., until the micro-needle array assembly 360 is connected to the electronic device assembly 370 through the connection of each connector, the second PCB connector 430, and the first PCB connector 470).

[0126] At 704, in response to a trigger event, the power connection circuit 620 establishes a connection between the battery 460 and one or more electronic components of the sensor assembly 350. In some variations, the one or more electronic components may include the boost circuit 520, the microcontroller 510, and / or the peripheral power switch 630. The trigger event may be the detection of light by the light detection circuit 610. When light is detected, the light detection circuit 610 can send a signal to the power connection circuit 620 to command the power connection circuit 620 to close its switch and connect the battery 460 to the rest of the sensor assembly 350.

[0127] At 706, the microcontroller 510 starts a boot sequence and asserts a main power latch. For example, when the battery 460 and the microcontroller 510 are connected (e.g., the battery 460 is supplying power to the microcontroller 510), the microcontroller 510 can implement a boot sequence and / or assert a main power latch so that the microcontroller 510 can start operating.

[0128] At 708, the microcontroller 510 issues a start command. For example, the microcontroller 510 can issue a start command to the boost circuit 520 and the peripheral power switch 630. As shown by 708a, 708b, and 708c, one or more factors can contribute to the issuance of the start command. In some variations, as shown by 708a, when the microcontroller 510 is turned on (e.g., at 706), the microcontroller 510 may start a timer using the real-time clock 506. After a predetermined period has elapsed, the microcontroller 510 can issue a start command. The predetermined period may be used as a safety measure to ensure that sufficient time has elapsed when a trigger event occurs. In some variations, as shown by 708b, the issuance of the start command may be based on a start command from a remote device (e.g., transmitted via a communication link). In some variations, as shown by 708c, the issuance of the start command may be based on one or more sensor signals. For example, signals from the motion sensor 512 and / or the ambient light sensor 508 can be used to determine whether the microcontroller 510 should issue a start command.

[0129] At 710, in response to the start command from the microcontroller 510, the analog front end 502 can be turned on.

[0130] At 712, a micro-needle insertion verification process can be performed. For example, the analog front end 502 may apply a bias potential between one or more electrodes to determine whether the micro-needles of the micro-needle array 140 are inserted to a sufficient depth into the user's skin. The bias can be applied between the working electrode and the reference electrode / counter electrode. The resulting current or resistance between the electrodes may be compared to a threshold value indicating a range of values indicative of insertion. If the resulting current or resistance is within the range, this serves as an indicator that the micro-needle array 140 has been inserted to a sufficient depth. If the resulting current is not within the range, it may be determined that the micro-needle array 140 is not at a sufficient depth for analyte sensing. Additional details regarding micro-needle insertion verification are provided with reference to FIGS. 9A-9B. In some variations, the micro-needle insertion verification process at 712 is not implemented.

[0131] At 714, the analog front end 502 transitions to active sensing. The transition to active sensing may be in response to the verification of micro-needle insertion at 712. At 712, if the verification process indicates that the micro-needles are not properly inserted, the process may end. However, if the verification process indicates that the micro-needles of the micro-needle array 140 are properly inserted, a transition to active sensing occurs that includes the application of a bias potential higher than the bias potential applied during the verification of micro-needle insertion. The bias potential is applied between the working electrode and the reference electrode of the analyte monitoring device 110 as further described herein.

[0132] At 716, the brightness of the LED 518 is controlled based on the ambient light. In some variations, in the active sensing mode, the light conditions within and / or surrounding the environment of the analyte monitoring device 110 are monitored to control the brightness of the LED. For example, the signal from the ambient light sensor 508 is monitored and correlated with one of a plurality of brightness levels. The brightness levels can define the brightness of the LED (e.g., brightest, dimmer, darkest, off). Additional details regarding the ambient light sensor are provided below.

[0133] At 718, in response to a determination that the battery life of the battery 460 is approaching its end, or based on the operation limit time, the microcontroller 510 can enter a low power state. For example, the microcontroller 510 may determine that the voltage level of the battery 460 is low and / or that the expected end-of-life of the battery 460 is approaching, and in response, enter a low power state to conserve the battery 460. In some variations, the microcontroller 510 may determine that an operation limit time, which is a pre-defined and stored value, has been met. To further extend the life of the battery 460, it may enter a low power state. In the low power state, the microcontroller 510 may cut off power to one or more electronic components that are not involved in analyte detection and measurement (e.g., the motion sensor 512, the ambient light sensor 508, other sensors 632, the output device 634, the LED 518), etc. In some variations, in the low power state, the microcontroller 510 may adjust the use of one or more electronic components.

[0134] At 720, in some variations, data from the communication controller 514 is downloaded from the analyte monitoring device 110. When the battery 460 is depleted, the ambient power generation module 640 can be used to extract and / or download data such as analyte measurement values and operation data regarding the operation of the analyte monitoring device 110.

[0135] In some variations, it may be desirable to power on the microcontroller 510 for an update such as a firmware update. Further, it may be desirable to do so when the analyte monitoring device 110 is housed in a package or applicator device and is not yet ready for use. In such situations (e.g., when an update is desirable, the analyte monitoring device 110 is not yet ready for use, and there is an unknown period until the analyte monitoring device 110 is ready for use), if the battery 460 is connected to the microcontroller 510, the battery 460 will be at least partially depleted when the analyte monitoring device 110 is applied to the user and is to start the intended sensing operation. Implementations of the present subject matter incorporate an ambient power generation module 640 to power the microcontroller 510 to enable an update to be applied. If a communication field is present, the communication field supplies energy to the ambient power generation module 640. The ambient power generation module 640 is connected to the microcontroller 510 and can thus power on the microcontroller 510 for an update provided via the communication field. When the communication field is removed from the analyte monitoring device 110, the microcontroller 510 returns to the shutdown mode until it is powered on again by the ambient power generation module 640 or the battery 460.

[0136] In some cases, the analyte monitoring device 110 may encounter a spurious communication field (e.g., a communication field not intended to provide a firmware update). For example, in a manufacturing environment, a transportation environment, or a distribution environment, the analyte monitoring device 110 may be in the presence of a communication field. Due to the ambient power generation module 640, the microcontroller 510 may be powered on in an unintended situation (e.g., when it is not necessary to power on the microcontroller 510). In a variant, in response to being powered on or receiving a power-on signal, the microcontroller 510 determines whether the power-on event that powered on the microcontroller 510 is a valid power-on event. In some variants, the microcontroller 510 determines whether a valid source caused the power-on event. By determining whether the power-on event is a valid power-on event and / or by determining the source of the power-on event, the microcontroller 510 responds to the power-on event by entering a mode corresponding to the power-on event and / or the power-on source.

[0137] In some variants, a valid power-on event is defined as a transition to an operable state of the analyte monitoring device 110 or an intentional placement within the communication field of the analyte monitoring device 110. In particular, when the analyte monitoring device 110 transitions to an operable state, this transition determination or confirmation enables the microcontroller 110 to respond accordingly by transitioning the analyte monitoring device 110 to a startup sequence. When the analyte monitoring device 110 is intentionally placed within the communication field, this determination or confirmation of the intentional placement enables the microcontroller 110 to execute an update based on the received communication and respond by transitioning to a power-off mode when the update is complete. If the power-on event is invalid and / or the source is not a valid source, the microcontroller 110 responds accordingly by transitioning to a power-off mode.

[0138] In some variations, in response to powering on, the microcontroller 510 determines whether the power-on event is a valid power-on event by determining whether the analyte monitoring device 110 has transitioned to a usable state. The usable state may be a state in which a battery is connected to the microcontroller 510. The usable state may be a state in which the analyte monitoring device 110 is ready to be applied to the user, removed from the applicator device, or applied to the user. In some variations, the usable state may be a pre-insertion environment in which the analyte monitoring device 110 is ready for application, or a post-insertion environment in which the analyte monitoring device 110 is inserted into the user's skin surface.

[0139] The microcontroller 510 may determine whether the analyte monitoring device 110 is in a usable state based on data from one or more sources and / or sensors of the analyte monitoring device 110. For example, one or more sensors and related data from the one or more sensors may be used to determine a change in the environment of the analyte monitoring device 110. In one implementation, the light data from the ambient light sensor 508 may be used. For example, the analyte monitoring device 110 may be maintained in a darkened environment until the user is ready to apply and use the analyte monitoring device 110. When the analyte monitoring device 110 is removed from the darkened environment, or when the darkened environment changes and is exposed to at least some light, such as when a cap, package, or protective cover is removed, light is detected, and this light may be an indicator that the user has transitioned the analyte monitoring device 110 to a usable state. When the power is turned on, the microcontroller 510 may query the ambient light sensor 508, receive a light data measurement, and compare the light data measurement to a light threshold determined to indicate that the analyte monitoring device 110 has transitioned to a usable state (e.g., removed from a darkened environment or the darkened environment has changed sufficiently to indicate that the user is preparing to apply the analyte monitoring device 110). If the light data measurement meets or exceeds the light threshold, the microcontroller 510 may be able to initiate a startup sequence. The startup sequence may include the microcontroller 510 entering an idle mode, remaining in the idle mode for a predetermined period, and entering an operating mode. The predetermined period may be a time sufficient to ensure that the analyte monitoring device 110 has been applied to the user. In some variations, the startup sequence may include directly transitioning the microcontroller 510 to the operating mode.In this variant where light is used to determine the transition to an operable state, a transition resulting from removal from a darkened environment or a change to a darkened environment causes the light detection circuit 610 to generate a signal to the power connection circuit 620 to close the switch, thereby establishing a connection between the battery 460 and the microcontroller 510.

[0140] In an alternative variant, magnetic field data may be used to indicate whether the analyte monitoring device 110 is in an operable state. In the variant, the magnet is fixed or disposed within the applicator device or package of the analyte monitoring device 110, including a magnetic switch such as a digital magnetic switch (e.g., a tunnel magnetoresistance (TMR) switch). The magnet and the magnetic switch are arranged and positioned such that the magnet and the magnetic switch are aligned when the analyte monitoring device 110 is housed within the applicator device or package. When the analyte monitoring device 110 is removed from the applicator device or package (e.g., transitioned to an operable state), the magnetic field no longer exists due to the removal of the analyte monitoring device 110 from the applicator device or package, and an input signal (e.g., a power-on signal) is sent to the microcontroller 510. The microcontroller 510 uses the signal from the magnetic switch to confirm a valid power-on event and initiate a startup sequence. The startup sequence may include the microcontroller 510 entering an idle mode and then, after a predetermined period, or in response to confirming that the power-on signal has come from the magnetic switch, entering an operating mode. In some variants, the startup sequence may include directly transitioning the microcontroller 510 from an idle mode to an operating mode without an idle mode.

[0141] In a variant form, the multi-axis magnetic switch may be incorporated into the analyte monitoring device 110, and the applicator device or package may include a plurality of (e.g., at least two) magnets that are aligned with the multi-axis magnetic switch of the analyte monitoring device 110. The plurality of magnets are oriented such that each magnet generates a magnetic field in a direction different from other magnetic fields. This implementation requires that the magnetic fields in a plurality of directions need to be removed before the magnetic switch is triggered.

[0142] In another variant form, the accelerometer data from the motion sensor 512 can be used to indicate whether the analyte monitoring device 110 is in a usable state. The acceleration threshold value determined to indicate that the analyte monitoring device 110 is deployed from the applicator device may be stored and used to determine whether the analyte monitoring device has transitioned to a usable state (e.g., removed from the applicator device and inserted onto the user's skin surface). The microcontroller 510 may be powered in a low-power state while monitoring the data from the motion sensor 512. In response to a determination that the acceleration data from the motion sensor 512 meets or exceeds the acceleration threshold value, the microcontroller 510 uses the signal from the motion sensor 512 to confirm a valid power-on event and starts the startup sequence. The startup sequence may include the microcontroller 510 entering the idle mode and then entering the operating mode after a predetermined period. In some variant forms, the startup sequence may include directly transitioning the microcontroller 510 from the idle mode to the operating mode without the idle mode.

[0143] In another variant, capacitance data from a capacitance sensor can be used to indicate whether the analyte monitoring device 110 is in a usable state. In the variant, the target is fixed or disposed within the applicator device or package of the analyte monitoring device 110, which includes a capacitance sensor that generates an electrostatic field. The target and the capacitance sensor are arranged and positioned such that when the analyte monitoring device 110 is housed within the applicator device or package, the target and the capacitance sensor are aligned. When the analyte monitoring device 110 is removed from the applicator device or package (e.g., transitioned to a usable state), the capacitance sensor transmits an input signal (e.g., a power-on signal) to the microcontroller 510. In another implementation, when the analyte monitoring device 110 is applied to a user, the capacitance sensor detects the skin (which is the target in this implementation). Upon detecting the skin, the capacitance sensor sends a signal to the microcontroller.

[0144] The microcontroller 510 uses the signal from the capacitance sensor to confirm a valid power-on event and initiate a startup sequence. The startup sequence may include the microcontroller 510 entering an idle mode and then, after a predetermined period or in response to verifying that the power-on signal has come from the capacitance sensor, entering an operating mode. In some variants, the startup sequence may include directly transitioning the microcontroller 510 from an idle mode to an operating mode without an idle mode.

[0145] Multiple sources or sensors may provide data used to determine whether a power-on event is a valid power-on event by determining whether the analyte monitoring device 110 has transitioned to a usable state. For example, optical data, magnetic field data, accelerometer data, and capacitance data may be used in various combinations to determine whether the analyte monitoring device 110 is in a usable state. One or more additional data sources can be used as a check or verification of the first source.

[0146] As described above, a valid power-on event may include the intentional placement of the analyte monitoring device 110 in the communication field. When the analyte monitoring device 110 is intentionally placed within the communication field, upon determination or confirmation of this intentional placement, the microcontroller 110 can respond by performing an update based on the communication received via the communication field.

[0147] In a variant form, when the analyte monitoring device 110 has not transitioned to an operable state, the microcontroller 510 determines whether the analyte monitoring device 110 has been intentionally placed within the communication field. The intentional placement of the analyte monitoring device 110 within the communication field is defined as a valid power-on event because it serves as an indicator that a communication field has been generated for a remote device to send an update to the analyte monitoring device 110. The intentional placement is determined based on the detection of the communication field and subsequent reception of a wireless transmission from the remote device within a predetermined period. The communication field can be detected by measuring the voltage generated by the ambient power generation module 640. When the ambient power generation module 640 generates a signal (e.g., voltage level) detected by the microcontroller 510, this serves as an indicator of the detected communication field. After detecting the communication field, the microcontroller 510 waits for a predetermined period to receive a wireless transmission from the remote device. If the predetermined period elapses without a wireless transmission, the detected communication field is considered unintentional and / or spurious (e.g., not directed at the analyte monitoring device 110). If a wireless transmission is received within the predetermined period, the power-on event is considered a valid power-on event and the analyte monitoring device 110 transitions to the reconfiguration mode.

[0148] In the reconfiguration mode, the microcontroller 510 applies the reconfiguration parameters included in the wireless transmission from the remote device. For example, the remote device may be an NFC-enabled device configured to provide a firmware update to the analyte monitoring device 110. The NFC-enabled device is disposed in proximity to the analyte monitoring device 110 and transmits the uploaded firmware update.

[0149] Following completion of the reconfiguration mode, the analyte monitoring device 110 transitions to the power-off mode. The analyte monitoring device 110 remains in the power-off mode until a power-on event occurs again, and when a power-on event occurs again, the analyte monitoring device 110 determines whether the power-on event is valid.

[0150] If the analyte monitoring device 110 does not transition to an operable state and is not intentionally placed within the communication field (e.g., if the power-on event is not a valid power-on event), the analyte monitoring device 110 transitions to the power-off mode. In some variations, transitioning to the power-off mode in response to determining that the power-on event is not valid may include activating a watchdog timer and attempting to shut down. If the shutdown is successful, the analyte monitoring device 110 is in the power-off mode. If the shutdown is not successful, the watchdog timer causes a reset to determine the cause for which the microcontroller 510 was powered on.

[0151] In some variations, in response to power-on, the microcontroller 510 determines the source of the power-on event and causes the analyte monitoring device 110 to transition to an operating mode corresponding to the determined source of the power-on event. The source of the power-on event may be a connection to the battery 460 or power received from the ambient power generation module 640. When the determined source of the power-on event is a connection to the battery 460, the corresponding operating mode may be a startup mode that includes a sequence from the idle mode to the operating mode. The analyte monitoring device 110 may transition from the idle mode to the operating mode after confirmation of the insertion event. Confirmation of the insertion event may be based on one or more of elapsed time (e.g., waiting for a predetermined period before transitioning from the idle mode to the operating mode), accelerometer data confirming that an acceleration threshold is met (e.g., the analyte monitoring device 110 is applied to the user), a current or resistance resulting from an applied bias potential, and communication from an external device (e.g., a remote device may issue a command to confirm that the analyte monitoring device 110 is applied).

[0152] In some variations, when the determined source of the power-on event is power received from the ambient power generation module 640, the corresponding operating mode may be a reset mode. The reset mode may include receiving a wireless transmission, reconfiguring the microcontroller 510 according to the reconfiguration parameters included in the wireless transmission, and transitioning to the power-off mode. The reset mode may include enabling a watchdog timer and attempting to shut down if there is no communication field or if no wireless transmission is received. If the shutdown is not successful, the reset mode may further include determining whether the analyte monitoring device 110 has transitioned to a usable state.

[0153] In some variations, the power-on event may be the power-on of the microcontroller 510 or the receipt of a power-on signal by the microcontroller 510. In some variations, the microcontroller 510 may determine whether the battery 460 is the source of the power-on event based on a signal between the battery 460 and the microcontroller 510. In some variations, determining the source of the power-on event may include determining whether the analyte monitoring device 110 has transitioned to a usable state. The transition to a usable state may be based on non-analyte sensor data such as optical data, magnetic field data, accelerometer data, and capacitance data as described above.

[0154] Figure 8 shows a flowchart 800 of the power-up process of the analyte monitoring device. The power-up process begins at 802, where the power of the analyte monitoring device 110 is turned off and it is housed within the applicator device.

[0155] At 804, the power of the controller is turned on. Turning on the power initiates a process in which the controller determines the source of the power-on event and transitions to an operating mode corresponding to the determined source. In some variations, if the source is the battery or an intentional communication field, the power-on event is considered a valid power-on event. In some variations, the power-on event is a valid power-on event if the analyte monitoring device 100 has transitioned to a usable state or if the analyte monitoring device has been intentionally placed within a communication field. In response to any of these valid power-on events, the controller responds by transitioning to the corresponding mode. If the source is an unintentional communication field (e.g., not a valid power-on event), the controller responds by attempting to shut down within a period defined by a watchdog timer. If the shutdown is unsuccessful, the process of determining the source of the power-on is repeated.

[0156] At 806, the controller uses data from the sensor to determine whether the power-on event is the result of the analyte monitoring device 110 transitioning to an operable state where the source of the power-on event is a connection to the battery. The operable state may be a state where the analyte monitoring device 110 is ready to be applied to the user, a state where it is removed from the applicator device, or a state where it is being applied to the user. In some variations, the operable state may be a pre-insertion environment where the analyte monitoring device 110 is ready for application, or a post-insertion environment where the analyte monitoring device 110 is inserted onto the user's skin surface. Specifically, at 806, the measured light from the ambient light sensor is compared to a light threshold. In other variations, alternative or additional data may be used to confirm the transition to the operable state and the connection to the battery.

[0157] In the case of an update such as a firmware update, while the analyte monitoring device 110 remains within the applicator device or other package, the measured light is not greater than the light threshold, and the process continues to 810.

[0158] At 810, a determination is made as to whether a communication field exists. If the communication field is detected, for example, by a measured signal between the controller and the ambient power generation module, the process continues to 812.

[0159] At 812, the controller waits for a wireless transmission. Upon receiving the wireless transmission, the controller receives the update reconfiguration parameters. At 814, the controller is reconfigured by the update and the analyte monitoring device 110 is updated to be provided to be ready for power-off. Next, the process proceeds to 802, at which point the power of the analyte monitoring device 110 is turned off.

[0160] In some situations, the controller may be in the presence of an unintended phantom communication field for the analyte monitoring device 110. In this situation, at 812, after detecting the communication field, the controller waits for a wireless transmission. If a predetermined period elapses without receiving a wireless transmission, the process proceeds to 816.

[0161] At 816, the watchdog timer is enabled and a shutdown is attempted. The watchdog timer is enabled if the shutdown fails because the analyte monitoring device 110 is powered on and cannot be shut down. For example, the light detection circuit 610 may be triggered, causing a connection between the battery 460 and the controller.

[0162] At 818, if the controller cannot shut down (e.g., if the shutdown attempt at 816 was unsuccessful), the process continues to 820. At 820, the watchdog timer causes a reset and the process continues to 806, at which point the process of comparing the measured light value to the light threshold is repeated. If the shutdown was successful at 818, the process proceeds to 802, at which point the analyte monitoring device 110 is in the powered-off state.

[0163] In some situations, the controller may be powered on by an unintended communication field for the analyte monitoring device 110, but by the time the controller checks for the communication field, the communication field no longer exists. In this situation, the process moves from 810 to 816, the watchdog timer is enabled, and a shutdown is attempted.

[0164] Figures 9A and 9B show exemplary schematic views of aspects of an analyte monitoring device for micro-needle insertion confirmation.

[0165] FIG. 9A shows an exemplary schematic diagram 900 showing the connection between the electronics of an analyte monitoring device and a microneedle array comprising a plurality of microneedles each having an electrode disposed on each of the respective microneedles. The schematic diagram 900 includes a representation of a microneedle array 140 having four working electrodes (a first working electrode needle 902, a second working electrode needle 903, a third working electrode needle 904, and a fourth working electrode needle 905), a reference electrode needle 906, and two counter electrodes (a first counter electrode needle 907 and a second counter electrode needle 908). In some variations, alternative configurations of the electrodes are used in the microneedle array 140. For example, some configurations may include fewer or additional working electrodes and counter electrodes. Some configurations may include additional reference electrodes. Details of an exemplary configuration of the microneedle array 140 are provided with reference to FIGS. 18A-18J, and other configurations may be used.

[0166] In the configuration of the schematic diagram 900, the two counter electrode needles, the first counter electrode needle 907 and the second counter electrode needle 908, are both shorted together. In this configuration, the two counter electrode needles function as one counter electrode. In a variation, the microneedle array may include only one counter electrode needle. In some variations, three or more counter electrode needles may be incorporated and shorted together.

[0167] The inputs of the analog front end 502 corresponding to the needles of the micro-needle array are also shown in schematic diagram 900. They are the first operation input 912, the second operation input 913, the third operation input 914, the fourth operation input 915, the reference input 916, and the counter input 917. The counter input 917 corresponds to the first counter electrode needle 907 and the second counter electrode needle 908 shorted together. The electronic device also includes two switches, namely, the first switch 922 between the counter input 917 and the reference input 916, and the second switch 924 at the reference input 916. The first switch 922 and the second switch 924 are used to configure the analyte monitoring device 110 as a three-electrode system configured to implement the analyte sensing operation described herein (as shown by the schematic diagram 900 in FIG. 9A), and as a two-electrode system depicted by the schematic diagram 950 in FIG. 9B that can be used for micro-needle insertion confirmation, as further described herein.

[0168] As shown in FIG. 9A, when the first switch 922 is open and the second switch 924 is closed, the reference input 916 and the counter input 917 are independent of each other. However, the combined counter / reference electrode reference point may be formed by closing the first switch 922 and opening the second switch 924, as shown in FIG. 9B. The combined counter / reference electrode reference point is connected to the counter input 917 of the analog front end and the reference input 916 of the analog front end, and it is this reference point that can be used to apply a bias potential to one or more working electrodes. In particular, the analog front end may apply a bias potential between the first working electrode needle 902 and the reference point and measure the resulting current and / or resistance at the first working electrode needle 902.

[0169] To confirm the insertion of the micro-needle array 140, the analog front end 502 applies a bias potential, which may be less than, approximately equal to, equal to, or greater than the bias potential of the sensing bias potential applied during analyte sensing. In some variations, the applied bias potential is a value known not to damage the sensing membrane and / or analyte confinement membrane of the working electrode. In some variations, one or more bias potentials are applied. For example, the bias potential may be applied between each of the working electrode pins 902, 903, 904, and 905 and a reference point.

[0170] In some variations, the bias potential is applied individually. In some variations, the bias potentials are applied sequentially such that one bias potential is applied at a time. Each resulting current and / or resistance is compared to a threshold value. The application of distinct bias potentials can provide additional confirmation of the insertion of the micro-needle array 140, for example, by confirming that two or more of the electrodes are inserted to a sufficient depth for sensing.

[0171] The resulting current and / or resistance is compared to a predetermined threshold value indicative of a value or range of values indicating insertion. If the resulting current and / or resistance is within the range, this serves as an indication that the micro-needle array 140 has been inserted to a sufficient depth. The analyte monitoring device 110 may transition to an operating mode in which an operating bias potential is applied. If the resulting current is not within the range, the micro-needle array 140 may not be at a sufficient depth for analyte sensing. A warning can be generated to notify the user. The user may attempt to re-insert the analyte monitoring device 110 and / or apply pressure to the analyte monitoring device 110 to achieve sufficient insertion of the micro-needle array 140. The warning and / or pressure application instructions may be provided on the user interface of the micro-needle array and / or on an application (e.g., a mobile app) running on a connected remote device.

[0172] In a variant form, the operating bias potential is applied only to the working electrode needles 902, 903, 904, or 905, and the current and / or resistance obtained from the applied bias potential meets or falls within a threshold value. It is possible that not all of the working electrode needles are fully inserted at a depth sufficient for sensing, which allows only those fully inserted at a sufficient depth to be used (for example, the operating bias potential is applied only to the working electrode needles determined to be fully inserted based on the resulting current and / or resistance).

[0173] In some variant forms, one or more dedicated electrode needles are used to confirm insertion, and one or more other electrode needles are used for sensing. For example, one of the working electrode needles 902, 903, 904, or 905 is used to apply a bias potential with reference to a reference point. If the current value or resistance value resulting from the applied bias potential meets or falls within a threshold value, one or more of the other working electrode needles 902, 903, 904, or 905 may be used to sense the operation to which the operating bias potential is applied. In some variant forms, one or more of the working electrode needles used to confirm insertion may include a conductive electrode. In some variant forms, one or more of the working electrode needles used to confirm insertion may include a conductive electrode with one or more other layers disposed thereon, as further described herein.

[0174] In some variant forms, before applying a first bias potential for insertion confirmation, the combined counter / reference electrode reference point may be formed by closing the first switch 922 and opening the second switch 924. When shifting the analyte monitoring device 110 to the operating mode, the first switch 922 is opened and the second switch 924 is closed.

[0175] In a variant form, to transition the analyte monitoring device 110 to an operating mode, it is necessary to confirm the insertion of a predetermined number of working electrode needles. In a variant form, at least one working electrode needle needs to be inserted such that the current and / or resistance resulting from the applied bias potential meets a threshold or falls within a threshold range. In some variant forms, most (e.g., more than 50%) of the working electrode needles designated for sensing or some other predefined number need to be inserted such that they are confirmed by the measured value of the applied bias potential. In a variant form, for the analyte monitoring system 110 to transition to an operating mode, most (e.g., more than 50%) of the working electrode needles designated to confirm insertion or some other predefined number need to be inserted (as confirmed by the measured value of the applied bias potential).

[0176] Once the analyte monitoring device is inserted and warm-up and any calibration are complete, the analyte monitoring device may be ready to provide sensor measurements of the target analyte. The target analyte (and any necessary cofactors) diffuses from the biological environment through the biocompatible and diffusion-limiting layer on the working electrode to the biorecognition layer containing the biorecognition element. In the presence of a cofactor (if present), the biorecognition element may convert the target analyte into an electroactive product.

[0177] A bias potential can be applied between the working electrode and the reference electrode of the analyte monitoring device, and a current can be passed from the counter electrode to maintain a fixed potential relationship between the working electrode and the reference electrode. Thereby, the electroactive product is oxidized or reduced, and a current flows between the working electrode and the counter electrode. The current value is proportional to the rate of the redox reaction at the working electrode and, specifically, is proportional to the concentration of the analyte of interest according to the Cottrell relationship as described in more detail above.

[0178] The current can be converted into a voltage signal by a transimpedance amplifier and quantized into a digital bit stream by an analog-to-digital converter (ADC). Alternatively, the current may be directly quantized into a digital bit stream by a current-mode ADC. The digital representation of the current is processed within an embedded microcontroller in the analyte monitoring device and relayed to a wireless communication module for broadcast or transmission (e.g., to one or more peripheral devices). In some variations, the microcontroller can perform additional algorithmic processing on the data to improve signal fidelity, accuracy, and / or calibration, etc.

[0179] In some variations, the digital representation of the current or sensor signal can correlate with an analyte measurement (e.g., a glucose measurement) by the analyte monitoring device. For example, the microcontroller can execute a programmed routine in the firmware to interpret the digital signal and perform any relevant algorithms and / or other analysis. By keeping the analysis on the analyte monitoring device, it can be possible to broadcast analyte measurements in parallel to multiple devices, for example, while ensuring that each connected device has the same information. Thus, generally, the user's target analyte (e.g., glucose) value can be estimated, stored in the analyte monitoring device, and communicated to one or more peripheral devices.

[0180] Data exchange can be initiated by either a mobile application or the analyte monitoring device. For example, the analyte monitoring device can notify the mobile application when new analyte data becomes available. The update frequency can vary, for example, between about 5 seconds to about 5 minutes and can depend on the type of data. Additionally or alternatively, the mobile application can request data from the analyte monitoring device (e.g., if the mobile application identifies a gap in the collected data due to disconnection, etc.).

[0181] If the mobile application is not connected to the analyte monitoring device, the mobile application may not receive data from the sensor electronics. However, the electronics within the analyte monitoring device may store each actual and / or estimated analyte data point. When the mobile application reconnects to the analyte monitoring device, the mobile application may request the data that was missing during the disconnection period, and the electronics on the analyte monitoring device may also transmit that data set (e.g., backfill).

[0182] Generally, the mobile application may be configured to provide a display of real-time or near real-time analyte measurement data on the display of the mobile computing device running the mobile application, etc. In some variations, the mobile application may communicate via a user interface regarding the analysis of analyte measurements, such as warnings, alarms, insights regarding trends, etc., in order to notify the user of analyte measurements that require attention or follow-up actions (e.g., high analyte measurements, low analyte measurements, high rates of change, analyte measurements outside of a preset range, etc.). In some variations, the mobile application may additionally or alternatively facilitate the communication of measurement data to the cloud for storage and / or archiving for later retrieval.

[0183] In some variations, the analyte monitoring device can be applied manually. For example, the user can remove the protective film on the adhesive layer and manually press the device onto their skin at the desired application site. As shown in FIG. 1, in some variations, the analyte monitoring device can be applied to the skin using a suitable applicator 160. The applicator 160 can be configured to bias the analyte monitoring device 110 towards the user's skin such that the micro-needle array 140 of the analyte monitoring device 110 can be inserted into the skin (e.g., to a desired target depth).

[0184] As described above, the analyte monitoring device is applied to the user's skin such that the microneedle array within the device penetrates the skin and the electrodes of the microneedle array are positioned in the upper dermis for access to interstitial fluid. For example, in some variations, the microneedle array can be geometrically configured to penetrate the outer layer of the skin, the stratum corneum, penetrate the epidermis, and rest within the papillary or upper reticular dermis. The sensing region limited to the electrodes in the distal region of each microneedle component of the array (as described above) can be configured to remain stationary and seated in the papillary or upper reticular dermis after application to ensure appropriate exposure to circulating interstitial skin fluid (ISF) without risk of bleeding or undue influence by nerve endings.

[0185] The analyte monitoring device may be applied at any suitable location, but in some variations, it may be desirable to avoid anatomical regions of thick or sagging skin (e.g., palm and sole regions), or regions that undergo significant flexion (e.g., elbow or patella). Suitable application sites can include, for example, the arm (e.g., upper arm, lower arm), shoulder (e.g., on the deltoid), back of the hand, neck, face, scalp, torso (e.g., on the back in the thoracic, lumbar, sacral regions, etc., or on the chest or abdomen), buttocks, leg (e.g., upper leg, lower leg, etc.), and / or the top of the foot.

[0186] In some variations, analyte measurement data and / or information regarding the analyte monitoring device can be communicated via the user interface of the analyte monitoring device. In some variations, the user interface of the analyte monitoring device can be used to communicate such information to the user in addition to, or instead of, communicating such information via a peripheral device, such as via a mobile application on a computing device. Thus, the user and / or people around the user can easily and intuitively view the analyte monitoring device itself for the purpose of evaluating analyte measurement data (e.g., the current and / or the trend of the analyte measurement level, such as the analyte measurement status) and / or the status of the device without having to look at a separate device (e.g., a peripheral device or other device that is remote from and communicating with the analyte monitoring device). Making such information directly available on the analyte monitoring device itself can also enable the user and / or people around the user to be warned more quickly about any concerns (e.g., analyte measurement values that are above or below the target range, and / or analyte measurement values that are increasing or decreasing at a surprising rate), thereby enabling the user to take appropriate corrective measures more quickly.

[0187] In some variations, a photodiode, phototransistor, photodetector, or other suitable ambient light sensor can be used to measure the illumination level in the immediate environment of the device. Ambient light measurements can be used, for example, to conserve battery charging in a power-saving mode, to improve contrast under various lighting scenarios, and / or to reduce the visibility of the device to other individuals, to trigger an adjustment (e.g., dimming) of the brightness of a user interface (e.g., a display, indicator lights, etc.). For example, an analyte monitoring device can enter a power-saving mode in response to measurements from an ambient light sensor indicating a general absence of ambient light (e.g., sufficient darkness for at least a predetermined period), such as when the device is placed under the wearer's clothing or when the wearer is sleeping in a dark environment. In these scenarios, a power-saving mode can be practical because indicator lights may have limited usefulness or may otherwise be perceived as bothersome (e.g., during sleep) when hidden and out of the wearer's line of sight (e.g., under clothing). In response to measurements from an ambient light sensor indicating exposure to ambient light (e.g., sufficient brightness for at least a predetermined period), the analyte monitoring device can then exit the power-saving mode and increase the brightness of the user interface accordingly.

[0188] In some variations, a mobile application can assist the user in managing the lifespan and replacement of the analyte monitoring device. For example, the mobile application can end data display when the wear period of the analyte monitoring device has elapsed.

[0189] Additionally or alternatively, the mobile application can provide the user with a configurable warning that the wearing period is about to elapse, whereby the user can apply a new analyte monitoring device when the current analyte monitoring device is still active but approaching its expiration date. Further, the new analyte monitoring device can warm up (typically in about 30 minutes to about 2 hours) while the old unit is still delivering analyte measurements. The old analyte monitoring device can then be removed at the end of use. The new analyte monitoring device can then become the primary sensor for delivering analyte measurements to the mobile application. This can provide uninterrupted coverage for analyte measurements. Additionally, readings from the old analyte monitoring device can be used to calibrate or algorithmically improve the accuracy of the new analyte monitoring device.

[0190] In some variations, the analyte monitoring device can have a unique serial number included within a microcontroller (e.g., disposed within an electronic device system). This serial number can enable tracking of the sensor from manufacture through product use. For example, a sensor device history record including manufacture and customer use may be transmitted and stored in a cloud database. This enables tracking and inference of various parameters such as individual user sensor performance metrics and improvements for individual users and sensor lots, quickly tracing defective sensor lots from field data to manufacturing or supplier issues, individualized health monitoring functions for individual users, and the like.

[0191] Via a web portal, the cloud infrastructure can also enable the user to view real-time and historical glucose data / trends and share the data with caregivers, healthcare provider(s), support network, and / or other appropriate persons.

[0192] The following provides an explanation of some exemplary aspects of an analyte monitoring device that may be used with the concepts described herein. In particular, the following explanation includes details of exemplary microneedle arrays, microneedle structures, and electrodes that may be used with the system components of the analyte monitoring device described herein.

[0193] As shown in the schematic diagram of FIG. 10A, in some variations, a microneedle array 1010 for use in sensing one or more analytes may include one or more microneedles 1010 protruding from a substrate surface 1002. The substrate surface 1002 may be, for example, substantially flat, and the one or more microneedles 1010 may protrude orthogonally from that flat surface. Generally, as shown in FIG. 10B, a microneedle 1010 can include a body portion 1012 (e.g., a shaft) and a tapered distal portion 1014 configured to pierce the user's skin. In some variations, the tapered distal portion 1014 can terminate in an insulated distal tip 1016. The microneedle 1010 may further have an electrode 1020 on the surface of the tapered distal portion. In some variations, electrode-based measurements can be performed at the interface between an electrode disposed in the body and interstitial fluid (e.g., on the outer surface of the entire microneedle). In some variations, the microneedle 1010 can have a solid core (e.g., a solid body portion), but in some variations, the microneedle 1010 can include one or more lumens that can be used, for example, for drug delivery or sampling of skin interstitial fluid. Other microneedle variations, as described below, can similarly include either a solid core or one or more lumens.

[0194] The micro-needle array 1000 may be at least partially formed from a semiconductor (e.g., silicon) substrate and includes various material layers applied and shaped using various suitable micro-electromechanical systems (MEMS) manufacturing techniques (e.g., deposition and etching techniques), as further described below. The micro-needle array can be reflow soldered to a circuit board, similar to a typical integrated circuit. Further, in some variations, the micro-needle array 1000 can include a three-electrode configuration including a working (sensing) electrode having an electrochemical sensing coating (including a biorecognition element such as an enzyme) that enables detection of a target analyte, a reference electrode, and a counter electrode. In other words, the micro-needle array 1000 may include at least one micro-needle 1010 including a working electrode, at least one micro-needle 1010 including a reference electrode, and at least one micro-needle 1010 including a counter electrode. Further details of these types of electrodes are described in more detail below.

[0195] In some variations, the microneedle array 1000 can include a plurality of microneedles insulated such that the electrodes on each microneedle within the plurality of microneedles are individually addressable and electrically insulated from all other electrodes on the microneedle array. The resulting individual addressability of the microneedle array 1000 can allow for greater control over the function of each electrode, since each electrode can be probed separately. For example, the microneedle array 1000 can be used to provide multiple independent measurements of a given target analyte, thereby improving the sensing reliability and accuracy of the device. Further, in some variations, the electrodes of the plurality of microneedles can be electrically connected to generate an enhanced signal level. As another example, in addition to or alternatively to examining the same microneedle array 1000, multiple analytes can be measured simultaneously to provide a more comprehensive assessment of a physiological state. For example, as shown in the schematic of FIG. 11, the microneedle array can include a portion of the microneedle for detecting a first analyte A, a second portion of the microneedle for detecting a second analyte B, and a third portion of the microneedle for detecting a third analyte C. It should be understood that the microneedle array can be configured to detect any suitable number of analytes (e.g., 1, 2, 3, 4, 5 or more, etc.). Suitable target analytes for detection can include, for example, glucose, ketones, lactate, and cortisol. For example, in some variations, ketones can be detected in a manner similar to that described in U.S. Patent Application No. 16 / 701784, which is hereby incorporated by reference in its entirety. Thus, the individual electrical addressability of the microneedle array 500 provides greater control and flexibility over the sensing function of the analyte monitoring device.

[0196] In some variations of the microneedle (e.g., a microneedle having a working electrode), the electrode 1020 may be disposed proximal to the insulated distal tip 1016 of the microneedle. In other words, in some variations, the electrode 1020 does not cover the tip of the microneedle. Rather, the electrode 1020 may be offset from the tip or apex of the microneedle. The electrode 1020 is proximal to or offset from the insulated distal tip 1016 of the microneedle and advantageously provides more accurate sensor measurements. For example, this arrangement prevents the concentration of the electric field at the microneedle tip 1016 during manufacturing, thereby avoiding non-uniform electrodeposition of the sensing chemistry on the electrode surface 1020 that could result in false sensing.

[0197] As another example, by disposing the electrode 1020 offset from the microneedle tip, the sensing accuracy is further improved by reducing unwanted signal artifacts and / or false sensor readings caused by stress during microneedle insertion. The distal tip of the microneedle is the first region to penetrate the skin and thus experiences the greatest stress caused by mechanical shearing phenomena associated with skin tearing or cutting. When the electrode 1020 is disposed at the tip or apex of the microneedle, this mechanical stress can cause the electrochemical sensing coating on the electrode surface to peel off when the microneedle is inserted and / or produce an interfering amount, albeit small, of tissue transported onto the active sensing portion of the electrode. Therefore, by disposing the electrode 1020 sufficiently offset from the microneedle tip, the sensing accuracy can be improved. For example, in some variations, the distal edge of the electrode 1020 can be disposed at least about 10 μm (e.g., about 20 μm to about 30 μm) from the distal tip or apex of the microneedle as measured along the longitudinal axis of the microneedle.

[0198] The body portion 1012 of the microneedle 1010 may further include a conductive path that extends between the electrode 1020 and a back electrode or other electrical contact (e.g., disposed on the back side of the substrate of the microneedle array). The back electrode may be soldered to the circuit board and can be in electrical communication with the electrode 1020 via the conductive path. For example, during use, the in vivo sensed current (inside the dermis) measured at the working electrode is examined by the back electrical contact, and the electrical connection between the back electrical contact and the working electrode is facilitated by the conductive path. In some variations, this conductive path can be facilitated by a metal via that passes through the interior of the microneedle body portion (e.g., the shaft) between the proximal and distal ends of the microneedle. Alternatively, in some variations, the conductive path may be provided by the entire body portion formed from a conductive material (e.g., doped silicon). In some of these variations, the complete substrate on which the microneedle array 1000 is constructed can be conductive, and each microneedle 1010 of the microneedle array 1000 can be electrically insulated from adjacent microneedles 1010 as described below. For example, in some variations, each microneedle 1010 within the microneedle array 1000 can be electrically insulated from adjacent microneedles 1010 using an insulating barrier that includes an electrically insulating material (e.g., a dielectric material such as silicon dioxide) that surrounds the conductive path extending between the electrode 1020 and the back electrical contact. For example, the body portion 1012 can include an insulating material that forms a sheath around the conductive path, thereby preventing electrical communication between the conductive path and the substrate. Other exemplary variations of the structure that enable electrical insulation between microneedles are described in more detail below.

[0199] Such electrical insulation between the micro-needles within the micro-needle array enables the sensors to be individually addressable. This individual addressability advantageously enables independent parallelized measurements between the sensors, as well as dynamic reconfiguration of the sensor assignments (e.g., for different analytes). In some variations, the electrodes of the micro-needle array can be configured to provide redundant analyte measurements, which is an advantage over conventional analyte monitoring devices. For example, redundancy can improve performance by improving accuracy (e.g., averaging multiple analyte measurements for the same analyte to reduce the effect of extremely high or low sensor signals on the determination of analyte levels), and / or can improve the reliability of the device by reducing the overall likelihood of failure.

[0200] In some variations, as will be described in more detail below using different variations of each of the micro-needles, the micro-needle array can be at least partially formed by suitable semiconductor and / or MEMS manufacturing techniques and / or mechanical cutting or dicing. Such processes can be advantageous, for example, to enable large-scale and cost-effective manufacture of the micro-needle array. For example, in some variations, the micro-needle array can be at least partially formed using the techniques described in U.S. Patent Application No. 15 / 913709, which is hereby incorporated by reference in its entirety.

[0201] Multiple exemplary variations of the micro-needle structure incorporating one or more of the above-described micro-needle features for the micro-needle array in an analyte monitoring device are described herein.

[0202] In some variations, the microneedle can have a generally columnar body portion and a tapered distal portion having an electrode. For example, FIGS. 12A-12C show exemplary variations of a microneedle 1200 extending from a substrate 1202. FIG. 12A is a schematic side cross-sectional view of the microneedle 1200, FIG. 12B is a perspective view of the microneedle 1200, and FIG. 12C is a detailed perspective view of the distal portion of the microneedle 1200. As shown in FIGS. 12B and 12C, the microneedle 1200 can include a columnar body portion 1212, a tapered distal portion 1214 terminating in an insulated distal tip 1216, and an annular electrode 1220. The annular electrode 1220 includes a conductive material (e.g., Pt, Ir, Au, Ti, Cr, Ni, combinations thereof, etc.) disposed on the tapered distal portion 1214, e.g., on a segment thereof, and includes a distal edge 1221a and a proximal edge 1221b. As shown in FIG. 12A, the annular electrode 1220 may be proximal to the distal tip 1216 (offset or spaced from the distal tip). The annular electrode 1220 can be electrically insulated from the distal tip 1216 by a distal insulating surface 1215a that includes an insulating material (e.g., SiO2). For example, the distal edge 1221a of the annular electrode 1220 may be proximate to the proximal edge of the insulated distal tip 1216 on the distal insulating surface 1215a. In some variations, the distal edge 1221a of the annular electrode 1220 can be proximal (e.g., immediately proximal, adjacent, abutting) to the proximal edge of the distal tip 1216 (the proximal edge of the distal insulating surface 1215a), but in other variations, the distal edge 1221a of the annular electrode 1220 can be distal (e.g., immediately distal, adjacent) to the proximal edge of the insulated distal tip 1216 (the proximal edge of the distal insulating surface 1215a) but still proximal to the tip itself. Thus, in some variations, the annular electrode 1220 may overlap on a portion of the distal insulating surface 1215a but may remain proximal to the insulated distal tip itself (and may be offset from the insulated distal tip itself).

[0203] Also, as shown in FIG. 12A, the proximal edge portion 1221b of the annular electrode 1220 may be distal to the columnar body portion 1212 and, in some variations, may be offset or spaced therefrom. In some variations, the proximal edge portion 1221b of the annular electrode 1220 may also be electrically insulated from the columnar body portion 1212 by a second distal insulating surface 1215b that includes an insulating material (e.g., SiO2) at the proximal end or region of the tapered distal portion 1214. For example, the proximal edge portion 1221b of the annular electrode 1220 may be proximate to the distal edge of the second distal insulating surface 1215b. In some variations, the proximal edge portion 1221b of the annular electrode 1220 may be proximal (e.g., immediately proximal, adjacent, abutting) to the distal edge of the second distal insulating surface 1215b, and in other variations, the proximal edge portion 1221b of the annular electrode 1220 may be distal (e.g., immediately distal, adjacent) to the distal edge of the second distal insulating surface 1215b but remain proximal to the columnar body portion 1212. Thus, in some variations, the annular electrode 1220 may overlap a portion of the second distal insulating surface 1215b but remain proximal to (and offset from) the columnar body portion 1212. As shown in FIG. 12A and some other variations, the annular electrode 1220 may be only on a portion of the surface of the tapered distal portion 1214 and may or may not extend to the columnar body portion 1212.

[0204] The electrode 1220 may be in electrical communication with a conductive core 1240 (e.g., a conductive path) that passes along the body portion 1212 to a backside electrical contact 1230 (e.g., made of a Ni / Au alloy) within or on the substrate 1202 or to another electrical pad. For example, the body portion 1212 may include a conductive core material (e.g., highly doped silicon). As shown in FIG. 12A, in some variations, an insulating mortise 1213 that includes an insulating material (e.g., SiO2) is disposed around the body portion 1212 (e.g., around the outer perimeter) and can extend at least partially through the substrate 1202. Thus, the insulating mortise 1213 can serve, for example, to prevent electrical contact between the conductive core 1240 and the surrounding substrate 1202. The insulating mortise 1213 may further extend onto the surface of the body portion 1212. The top and / or bottom surfaces of the substrate 1202 may also include a substrate insulating layer 1204 (e.g., SiO2). Thus, the insulation provided by the insulating mortise 1213 and / or the substrate insulator 1204 can at least partially contribute to the electrical insulation of the micro-needles 1200 that enables the addressability of the micro-needles 1200 within the micro-needle array. Further, in some variations, the insulating mortise 1213 that extends onto the surface of the body portion 1212 can function to enhance the mechanical strength of the micro-needle 1200 structure.

[0205] The microneedle 1200 can be formed at least partially by suitable MEMS manufacturing techniques such as plasma etching, also known as dry etching. For example, in some variations, the insulating mote 1213 around the body portion 1212 of the microneedle can be fabricated by first forming trenches in a silicon substrate by deep reactive ion etching (DRIE) from the back side of the substrate, and then filling those trenches with a SiO2 / polycrystalline silicon (poly-Si) / SiO2 sandwich structure by low-pressure chemical vapor deposition (LPCVD) or other suitable processes. In other words, the insulating mote 1213 can passivate the surface of the body portion 1212 of the microneedle and continue as an embedded feature within the substrate 1202 near the proximal portion of the microneedle. By mainly including compounds of silicon, the insulating mote 1213 can provide good filling and adhesion to adjacent silicon walls (such as the conductive core 1240, the substrate 1202, etc.). The sandwich structure of the insulating mote 1213 can further help provide an excellent match of the coefficient of thermal expansion (CTE) with adjacent silicon, thereby advantageously reducing failures, cracks, and / or other thermally induced vulnerabilities of the insulating structure 1213.

[0206] The tapered distal portion can be formed by isotropic dry etching from the front side of the substrate, and the body portion 1212 of the microneedle 1200 can be formed from DRIE. The front metal electrode 1220 may be deposited and patterned on the distal portion by special lithography (such as electron beam evaporation) that allows metal deposition to the desired annular region of the electrode 1220 without coating the distal tip 1216. Further, the Ni / Au backside electrical contact 1230 may be deposited by suitable MEMS manufacturing techniques (such as sputtering).

[0207] The microneedle 1200 can have any suitable dimensions. By way of example, in some variations, the microneedle 1200 may have a height of from about 300 μm to about 500 μm. In some variations, the tapered distal portion 1214 may have a tip angle of from about 60 degrees to about 80 degrees and a tip diameter of from about 1 μm to about 15 μm. In some variations, the surface area of the annular electrode 1220 may be from about 9000 μm2 to about 11000 μm2, or may include about 10,000 μm2. FIG. 13 shows various dimensions of an exemplary variation of a columnar microneedle having a tapered distal portion and an annular electrode, similar to the microneedle 1200 described above. The columnar microneedle of FIG. 13, similar to the microneedle 1200 described above, includes a columnar body portion, a tapered distal portion that terminates at an insulated distal tip, a contact trench formed within the tapered distal portion, and an annular electrode (designated "Pt" in FIG. 13) disposed over the tapered distal portion and covering the contact trench. The annular electrode can include a conductive material (e.g., Pt, Ir, Au, Ti, Cr, Ni, combinations thereof, etc.). In some variations, the contact trench may have a width of about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5 μm, about 10 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, about 50 μm, or as shown in FIG. 13, about 20 μm. The annular electrode may include a distal edge and a proximal edge, and in some variations, the distance between the distal edge and the proximal edge of the annular electrode may be about 20 μm, about 30 μm, about 40 μm, about 50 μm, about 60 μm, about 70 μm, about 80 μm, about 90 μm, about 100 μm, or as shown in FIG. 13, about 60 μm. In some variations, as shown in FIG. 13 by dimension callouts 60 μm and 20 μm, the annular electrode may overlap over a portion of the contact trench and, optionally, the insulating surface of the tapered distal portion (designated "oxide" in FIG. 13).

[0208] Figures 14A - 14F show another exemplary variant form of the microneedle 1400 having a substantially columnar body portion. The microneedle 1400 can be similar to the above - described microneedle 1000, except as described below. For example, as shown in FIG. 14B, similar to the microneedle 1200, the microneedle 1400 can include a columnar body portion 1412 and a tapered distal portion disposed on the cylinder 1413 and terminating at an insulated distal tip 1416. The cylinder 1413 may be insulated and may have a diameter smaller than that of the columnar body portion 1412. The microneedle 1400 includes a conductive material and may further include an annular electrode 1420 disposed in the tapered distal portion at a position proximal to (or offset or spaced from) the distal tip 1416. Other elements of the microneedle 1400 shown in FIGS. 14A - 14F have the same numbers as the corresponding elements of the microneedle 1000.

[0209] However, the electrode 1420 on the microneedle 1400 may include a tip contact trench 1422. This contact trench may be configured to help establish an ohmic contact between the electrode 1420 and the conductive core 1440 under the microneedle. In some variants, the shape of the tip contact trench 1422 is such that when the electrode 1420 material is deposited on the conductive core 1440, the electrode 1420 with the tip contact trench 1422 can have a stepped outer profile when viewed from the side, and may include an annular recess formed within the surface of the conductive core 1440 (e.g., within the body portion of the microneedle or otherwise in contact with a conductive path within the body portion). The tip contact trench 1422 can advantageously serve to provide a tolerance for ensuring contact between the electrode 1420 and the underlying conductive core 1440. Any of the other microneedle variant forms described herein may have a similar tip contact trench to help ensure contact between an electrode (which may be, for example, a working electrode, a reference electrode, a counter electrode, etc.) and a conductive path within the microneedle.

[0210] Figures 15A and 15B show further various dimensions of an exemplary variant of a columnar micro-needle having a tapered distal portion and an annular electrode, similar to the above-described micro-needle 1400. For example, the variant of the micro-needle shown in Figures 15A and 15B can have a tapered distal portion having a taper angle of generally about 80 degrees (or about 78 degrees to about 82 degrees, or about 75 degrees to about 85 degrees) and a cone diameter of about 140 μm (or about 133 μm to about 147 μm, or about 130 μm to about 150 μm). The cone of the tapered distal portion may be disposed on a cylinder such that the combination of the cone and the cylinder results in an overall height of about 110 μm (or about 99 μm to about 116 μm, or about 95 μm to about 120 μm). The annular electrode on the tapered distal portion can have an outer diameter or base diameter of about 106 μm (or about 95 μm to about 117 μm, or about 90 μm to about 120 μm), and an inner diameter of about 33.2 μm (or about 30 μm to about 36 μm, or about 25 μm to about 40 μm). The length of the annular electrode measured along the slope of the tapered distal portion can be about 57 μm (or between about 55 μm and about 65 μm), and the total surface area of the electrode can be about 12700 μm 2 (or about 12500 μm 2 to about 12900 μm 2 between, or about 12000 μm 2 to about 13000 μm 2 between). As shown in Figure 15B, the electrode can further have a tip contact trench that extends around the central region of the cone of the tapered distal portion, and the contact can have a width of about 11 μm (or about 5 μm to about 50 μm, about 10 μm to about 12 μm, or about 8 μm to about 14 μm) and a trench depth of about 1.5 μm (or about 0.1 μm to about 5 μm, or about 0.5 μm to about 1.5 μm, or about 1.4 μm to about 1.6 μm, or about 1 μm to about 2 μm) when measured along the slope of the tapered distal portion. The micro-needle has an insulated distal tip having a diameter of about 5.5 μm (or about 5.3 μm to about 5.8 μm, or about 5 μm to about 6 μm).

[0211] Details of an exemplary variant of the micro-needle array configuration are described in further detail below.

[0212] A plurality of microneedles (e.g., any of the microneedle deformation forms described in this specification, each of which may have the working electrode, counter electrode, or reference electrode described above) can be arranged in a microneedle array. Considerations for how to configure the microneedles include factors such as the desired insertion force for penetrating the skin with the microneedle array, optimization of electrode signal levels and other performance aspects, manufacturing costs, and complexity.

[0213] For example, the microneedle array may include a plurality of microneedles spaced apart at a predetermined pitch (the distance between the center of one microneedle and the center of its closest adjacent microneedle). In some deformation forms, the microneedles can be spaced apart at a pitch sufficient to disperse the force applied to the user's skin (e.g., to avoid the "rather like a needle" effect) for the microneedle array to penetrate the skin. As the pitch increases, the force required to insert the microneedle array tends to decrease, and the penetration depth tends to increase. However, it has been found that the pitch only begins to affect the insertion force at low values (e.g., less than about 150 μm). Therefore, in some deformation forms, the microneedles of the microneedle array can have a pitch of at least 200 μm, at least 300 μm, at least 400 μm, at least 500 μm, at least 600 μm, at least 700 μm, or at least 750 μm. For example, the pitch can be about 200 μm to about 80 μm, about 300 μm to about 700 μm, or about 400 μm to about 600 μm. In some deformation forms, the microneedles can be arranged in a periodic grid, and the pitch can be uniform across all directions and regions of the microneedle array. Alternatively, the pitch can be different when measured along different axes (e.g., the X and Y directions), and / or some regions of the microneedle array can include a smaller pitch, and other regions can include a larger pitch.

[0214] Furthermore, for more consistent penetration, the microneedles can be equally spaced from each other (e.g., the same pitch in all directions). For that purpose, in some variations, the microneedles within the microneedle array can be arranged in a hexagonal configuration as shown in FIGS. 16A-16C, FIGS. 17A-17B, and FIGS. 18A-18J. Alternatively, the microneedles of the microneedle array can be arranged in a rectangular array (e.g., a square array) or in another suitable symmetric manner.

[0215] Another consideration for determining the configuration of a microneedle array is the overall signal level provided by the microneedles. Generally, the signal level at each microneedle is invariant with respect to the total number of microneedle elements within the array. However, the signal level can be enhanced by electrically interconnecting multiple microneedles within the array. For example, an array having a large number of electrically connected microneedles is expected to generate a greater signal strength (and thus improved accuracy) than an array having fewer microneedles. However, a large number of microneedles on a die increases the die cost (for a given pitch) and also requires greater force and / or speed for insertion into the skin. In contrast, a smaller number of microneedles on a die reduces the die cost and enables insertion into the skin with reduced applied force and / or speed. Further, in some variations, a smaller number of microneedles on a die may reduce the overall footprint area of the die and may reduce undesirable local edema and / or erythema. Thus, in some variations, a microneedle array including 37 microneedles as shown in FIGS. 17A - 17B, or a microneedle array including 7 microneedles as shown in FIGS. 16A - 16D, can achieve a balance of these factors. However, in other variations, the number of microneedles within the array may be less (e.g., about 5 - about 35, about 5 - about 30, about 5 - about 25, about 5 - about 20, about 5 - about 15, about 5 - about 100, about 10 - about 30, about 15 - about 25, etc.), or the number of microneedles within the array may be more (e.g., greater than 37, greater than 40, greater than 45, etc.).

[0216] Furthermore, as will be described in more detail below, in some variations, only a subset of the micro-needles within the micro-needle array may be active during operation of the analyte monitoring device. For example, some of the micro-needles in the micro-needle array may be inactive (e.g., there is no signal read from the electrodes of the inactive micro-needles). In some variations, some of the micro-needles within the micro-needle array may be activated at a particular time during operation and may remain active for the remainder of the device's operating life. Further, in some variations, some of the micro-needles within the micro-needle array may be deactivated, additionally or alternatively, at a particular time during operation and may remain inactive for the remainder of the device's operating life.

[0217] Considering the characteristics of the die for the micro-needle array, the die size is a function of the number of micro-needles within the micro-needle array and the pitch of the micro-needles. Since the number of dice that can be formed from a single wafer of a given area increases, a smaller die size contributes to a lower cost, so manufacturing cost should also be considered. Further, a smaller die size is also less susceptible to the effects of brittle fracture due to the relative fragility of the substrate.

[0218] Furthermore, in some variations, the micro-needles at the periphery of the micro-needle array (e.g., near the edge or boundary of the die, near the edge or boundary of the housing, near the edge or boundary of the adhesive layer on the housing, along the outer edge of the micro-needle array, etc.) may be found to have better performance (e.g., sensitivity) due to better penetration compared to the micro-needles at the center of the micro-needle array or die. Thus, in some variations, the working electrodes may be disposed mostly or completely on the micro-needles disposed at the periphery of the micro-needle array to obtain more accurate and / or precise analyte measurements.

[0219] Figures 17A and 17B show exemplary schematic views of 37 microneedles arranged in an exemplary deformed configuration of the microneedle array 1700. The 37 microneedles can be arranged, for example, in a hexagonal array having a center-to-center pitch between the centers of each microneedle and the center of its immediately adjacent microneedle in any direction of about 750 μm (or about 700 μm to about 800 μm, or about 725 μm to about 775 μm). Figure 17A shows an exemplary schematic view of an exemplary deformed configuration of a die including the microneedle arrangement. Exemplary dimensions of the die (e.g., about 4.4 mm × about 5.0 mm) and the microneedle array 1700 are shown in Figure 17B.

[0220] Figures 16A and 16B show perspective views of exemplary schematic views of seven microneedles 1610 arranged in an exemplary deformed configuration of the microneedle array 1600. The seven microneedles 1610 are arranged in a hexagonal array on the substrate 1602. As shown in Figure 16A, the electrodes 1620 are arranged at the distal portions of the microneedles 1610 extending from the first surface of the substrate 1602. As shown in Figure 16B, the proximal portions of the microneedles 1610 are conductively connected to respective backside electrical contacts 1630 on the second surface of the substrate 1602 opposite the first surface of the substrate 1602. Figures 16C and 16D show a plan view and a side view of an exemplary schematic view of a microneedle array similar to the microneedle array 1600. As shown in Figures 16C and 16D, the seven microneedles are arranged in a hexagonal array having a center-to-center pitch between the centers of each microneedle and the center of its immediately adjacent microneedle in any direction of about 750 μm. In other deformed configurations, the center-to-center pitch between the needles may be, for example, about 700 μm to about 800 μm, or about 725 μm to about 775 μm. The microneedles can have an approximate outer shaft diameter of about 170 μm (or about 150 μm to about 190 μm, or about 125 μm to about 200 μm) and a height of about 500 μm (or about 475 μm to about 525 μm, or about 450 μm to about 550 μm).

[0221] Furthermore, the microneedle arrays described herein can have a high degree of configurability with respect to where the working electrode, counter electrode, and reference electrode are located within the microneedle array. This configurability can be facilitated by an electronic device system.

[0222] In some variations, the microneedle array can include electrodes distributed in two or more groups symmetrically or asymmetrically within the microneedle array, with each group characterized by the same or different number of electrode components according to the requirements of signal sensitivity and / or redundancy. For example, electrodes of the same type (e.g., working electrodes) may be distributed symmetrically on both sides or radially symmetrically within the microneedle array. For example, FIG. 18A shows a variation of a microneedle array 1800A that includes two symmetric groups of seven working electrodes (WE) with two groups of working electrodes labeled "1" and "2". In this variation, the two groups of working electrodes are distributed symmetrically on both sides within the microneedle array. The working electrodes are generally disposed between the central region of three reference electrodes (RE) and the outer peripheral region of twenty counter electrodes (CE). In some variations, each of the two groups of working electrodes can include seven working electrodes that are electrically connected to each other (e.g., to enhance the sensor signal). Alternatively, only a part of one or both of the groups of working electrodes may include a plurality of electrodes that are electrically connected to each other. As yet another alternative, the groups of working electrodes can be independent and include working electrodes that are not electrically connected to other working electrodes. Further, in some variations, the groups of working electrodes may be distributed in the microneedle array in an asymmetric or random configuration.

[0223] As another example, FIG. 18B shows a deformed form of the micro-needle array 1800B that includes four symmetric groups of three working electrodes (WE) each labeled "1", "2", "3", and "4". In this deformed form, the four working electrode groups are symmetrically distributed radially in the micro-needle array. Each working electrode group is adjacent to and symmetrically arranged with respect to one of the two reference electrode (RE) components in the micro-needle array. The micro-needle array also includes a counter electrode (CE) arranged around the micro-needle array, except for two electrodes on the hexagonal vertices that are inactive or can be used for other features or operating modes.

[0224] In some deformed forms, only a part of the micro-needle array may include active electrodes. For example, FIG. 18C shows a deformed form of the micro-needle array 1800C that has 37 micro-needles and a reduced number of active electrodes, including four symmetrically arranged working electrodes (labeled "1", "2", "3", and "4"), 22 counter electrodes, and three reference electrodes. The remaining eight electrodes of the micro-needle array are inactive. In the micro-needle array shown in FIG. 18C, each working electrode is surrounded by a group of counter electrodes. Two groups of such clusters of working electrodes and counter electrodes are separated by a row of three reference electrodes.

[0225] As another example, FIG. 18D shows a deformed form of the micro-needle array 1800D that has 37 micro-needles and a reduced number of active electrodes, including four symmetrically arranged working electrodes (labeled "1", "2", "3", and "4"), 20 counter electrodes, and three reference electrodes, with the remaining ten electrodes of the micro-needle array being inactive.

[0226] As another example, FIG. 18E shows a variant of the micro-needle array 1800E having 37 micro-needles and a reduced number of active electrodes including four working electrodes (labeled "1", "2", "3", and "4"), 18 counter electrodes, and two reference electrodes. The remaining 13 electrodes of the micro-needle array are inactive. The inactive electrodes are along the periphery of the overall micro-needle array, thereby reducing the effective size and shape of the active micro-needle arrangement to a smaller hexagonal array. Within the active micro-needle arrangement, the four working electrodes are generally in a radially symmetric arrangement, and each working electrode is surrounded by a group of counter electrodes.

[0227] FIG. 18F shows another exemplary variant of the micro-needle array 1800F having 37 micro-needles and a reduced number of active electrodes including four working electrodes (labeled "1", "2", "3", and "4"), two counter electrodes, and one reference electrode. The remaining 30 electrodes of the micro-needle array are inactive. The inactive electrodes are arranged in two layers around the periphery of the overall micro-needle array, thereby shrinking the effective size and shape of the active micro-needle arrangement to a smaller hexagonal array centered on the reference electrode. Within the active micro-needle arrangement, the four working electrodes are in a bilateral symmetric arrangement, and the counter electrodes are equidistant from the central reference electrode.

[0228] FIG. 18G shows another exemplary variant of the micro-needle array 1800G having 37 micro-needles and a reduced number of active electrodes. The active electrodes of the micro-needle array 1800G are arranged in the same manner as the micro-needle array 1800F shown in FIG. 18F, except that the micro-needle array 1800G includes one counter electrode and two reference electrodes, and a smaller hexagonal array of active micro-needles is centered around the counter electrode. Within the active micro-needle arrangement, the four working electrodes are in a bilateral symmetric arrangement, and the reference electrodes are equidistant from the central counter electrode.

[0229] FIG. 18H shows another exemplary variant of a micro-needle array 1800H having seven micro-needles. The micro-needle arrangement includes two micro-needles assigned as independent working electrodes (1 and 2), a counter electrode condition consisting of four micro-needles, and a single reference electrode. The arrangement of the working electrodes and the counter electrode equidistant from the central reference electrode has left-right symmetry. Further, the working electrodes are arranged as far as possible from the center of the micro-needle array (e.g., the die or the periphery of the array) to utilize positions where the working electrodes are expected to have higher sensitivity and overall performance.

[0230] FIG. 18I shows another exemplary variant of a micro-needle array 1800I having seven micro-needles. The micro-needle arrangement includes four micro-needles assigned as two independent groups (1 and 2) of two working electrodes each, a counter electrode consisting of two micro-needles, and a single reference electrode. The arrangement of the working electrodes and the counter electrode equidistant from the central reference electrode has left-right symmetry. Further, the working electrodes are arranged as far as possible from the center of the micro-needle array (e.g., the die or the periphery of the array) to utilize positions where the working electrodes are expected to have higher sensitivity and overall performance.

[0231] FIG. 18J shows another exemplary variant of a micro-needle array 1800J having seven micro-needles. The micro-needle arrangement includes four micro-needles assigned as independent working electrodes (1, 2, 3, and 4), a counter electrode condition consisting of two micro-needles, and a single reference electrode. The arrangement of the working electrodes and the counter electrode equidistant from the central reference electrode has left-right symmetry. Further, the working electrodes are arranged as far as possible from the center of the micro-needle array (e.g., the die or the periphery of the array) to utilize positions where the working electrodes are expected to have higher sensitivity and overall performance.

[0232] Figs. 18A - 18J illustrate exemplary variant forms of the micro - needle array configuration. However, these figures are not limiting, and it should be understood that other micro - needle configurations (including different numbers and / or distributions of working electrodes, counter electrodes, and reference electrodes, as well as different numbers and / or distributions of active and inert electrodes, etc.) may be suitable for other variant forms of the micro - needle array.

[0233] As described above, each micro - needle within the micro - needle array may include an electrode. In some variant forms, multiple different types of electrodes can be included among the micro - needles of the micro - needle array. For example, in some variant forms, the micro - needle array can function as an electrochemically operable electrochemical cell using three types of electrodes. In other words, the micro - needle array may include at least one working electrode, at least one counter electrode, and at least one reference electrode. Thus, the micro - needle array may include three different electrode types, but one or more of each electrode type can form a complete system (for example, the system can include multiple separate working electrodes). Further, multiple separate micro - needles can be electrically joined to form a valid electrode type (for example, a single working electrode may be formed from two or more connected micro - needles having a working electrode site). Each of these electrode types can include a metallization layer and can include one or more coatings or layers on the metallization layer that help facilitate the function of the electrode.

[0234] Generally, a working electrode is an electrode at which oxidation and / or reduction reactions of the target analyte occur for detection of the target analyte. A counter electrode functions to supply (feed) or sink (accumulate) the electrons necessary to sustain the electrochemical reaction at the working electrode via an electric current. A reference electrode functions to provide a reference potential to the system. That is, the potential at which the working electrode is biased is referenced to the reference electrode. A fixed, time-varying, or at least controlled potential relationship is established between the working electrode and the reference electrode, and within practical limits, no current is supplied from or sunk to the reference electrode. Further, to implement such a three-electrode system, an analyte monitoring device can include a suitable potentiostat or electrochemical analog front end to maintain a fixed potential relationship between the working electrode and the reference electrode in the electrochemical system (via an electronic feedback mechanism), while the counter electrode can be dynamically varied in potential to maintain the oxidation-reduction reaction of the target.

[0235] As described above, a working electrode is an electrode at which oxidation and / or reduction of the target occurs. In some variations, sensing may be performed at the interface between the working electrode disposed in the body and the interstitial fluid (e.g., on the outer surface of the entire micro needle). In some variations, the working electrode can include an electrode material and a biorecognition layer on which a biorecognition element (e.g., an enzyme) is immobilized to facilitate selective analyte quantification. In some variations, the biorecognition layer can also function as an interference blocking layer and can help prevent direct oxidation (or reduction) of endogenous and / or exogenous species at the electrode. In some variations, the biorecognition layer and the interference blocking layer can be separate and distinct layers. In some variations, in addition to the biorecognition layer and / or the combined biorecognition and interference blocking layer, an electrode protection layer may be provided for additional protection of the electrode.

[0236] The redox current detected at the working electrode can correlate with the detected concentration of the target analyte. This is because assuming a steady-state diffusion-limited system, the redox current detected at the working electrode follows the following Cottrell relationship.

Number

[0237] Furthermore, since the detection current is a direct function of the electrode surface area A, the sensitivity of the sensor (e.g., amperes per mole of analyte) can be increased by increasing the surface area of the electrode. For example, a plurality of single working electrodes can be grouped into an array of two or more components to increase the total effective sensing surface area. For redundancy, a plurality of working electrodes can be operated as a parallelized sensor to obtain a plurality of independent measurements of the concentration of the target analyte. The working electrode can operate as an anode (such that the analyte is oxidized on its surface) or as a cathode (such that the analyte is reduced on its surface).

[0238] FIG. 19A shows a schematic diagram of an exemplary set of layers for the working electrode 1910. For example, as described above, in some variations, the working electrode 1910 can include an electrode material 1912 and a biorecognition layer 1914 that includes a biorecognition element. The electrode material 1912 functions to facilitate the electrocatalytic detection of the analyte or the product of the reaction between the analyte and the biorecognition element. The electrode material 1912 also provides an ohmic contact and routes the electrical signal from the electrode catalytic reaction to the processing circuit. In some variations, the electrode material 1912 may include platinum. However, the electrode material 1912 may alternatively include, for example, palladium, iridium, rhodium, gold, ruthenium, titanium, nickel, carbon, doped diamond, or other suitable catalysts and inert materials.

[0239] In some variations, the electrode material 1912 may be coated with a highly porous electrode catalyst layer and / or an electrode roughening layer 1917, which can increase the electrode surface area to enhance sensitivity. The electrode roughening layer 1917 may enable the electrocatalytic oxidation or reduction of the products of the biorecognition reaction facilitated by the biorecognition layer 1914. However, in some variations, the electrode roughening layer 1917 may be omitted. In the absence of the electrode roughening layer 1917, the electrode may enable the electrocatalytic oxidation or reduction of the products of the biorecognition reaction.

[0240] The biorecognition layer 1914 may be disposed on the electrode material 1912 (or the electrode roughening layer 1917 if present), and functions to immobilize and stabilize the biorecognition element, thereby facilitating the long-term quantification of selective analytes. In some variations, the biorecognition element may include an enzyme such as oxidase. As an exemplary variation for use in a glucose monitoring system, the biorecognition element may include glucose oxidase, which, in the presence of oxygen, converts glucose into an electroactive product (i.e., hydrogen peroxide) detectable at the electrode surface. Specifically, the redox equation associated with this exemplary variation is: glucose + oxygen + hydrogen peroxide (mediated by glucose oxidase); hydrogen peroxide + oxygen in water (mediated by applying an oxidation potential to the working electrode).

[0241] However, in other variations, the biorecognition element may additionally or alternatively include another suitable oxidase or oxidoreductase enzyme such as lactate oxidase, alcohol oxidase, β-hydroxybutyrate dehydrogenase, tyrosinase, catalase, ascorbic acid oxidase, cholesterol oxidase, choline oxidase, pyruvate oxidase, uric acid oxidase, urease, and / or xanthine oxidase.

[0242] In some variations, the biometric element may be cross-linked with an amine-condensed carbonyl species that can help stabilize the biometric element within the biometric layer 1914.

[0243] In some variations, the working electrode may further include a diffusion-limiting layer 1915 disposed on top of the biometric layer 1914. The diffusion-limiting layer 1915 can function to limit the flux of the analyte of interest in order to reduce the sensitivity of the sensor to endogenous oxygen fluctuations. For example, the diffusion-limiting layer 1915 can attenuate the concentration of the analyte of interest such that it becomes a limiting reactant for an aerobic enzyme. However, in some variations (e.g., when the biometric element is not aerobic), the diffusion-limiting layer 1915 may be omitted.

[0244] In some variations, the working electrode may further include a hydrophilic layer 1916 or a biocompatible layer that provides a biocompatible interface, for example, to reduce foreign object response. The hydrophilic layer may be added, for example, by plasma polymerization techniques or grafting techniques. In some variations, the hydrophilic layer 1916 may be omitted (e.g., when the diffusion-limiting layer exhibits a hydrophilic moiety to serve this purpose).

[0245] In some variations, an electrode protection layer 1918 may be disposed on top of the electrode roughening layer 1917. The biometric layer 1914 is disposed on top of the electrode protection layer 1918. The diffusion-limiting layer 1915 can function to limit the flux of the analyte of interest in order to reduce the sensitivity of the sensor to endogenous oxygen fluctuations. Any hydrophilic layer 1916 is disposed on top of the diffusion-limiting layer 1915 to provide a biocompatible interface and reduce foreign object response.

[0246] In some variations, the electrode protection layer 1918 may be disposed on top of the electrode material 1912. The biometric layer 1914, which may include interference removal components, may be disposed on top of the electrode protection layer 1918. The diffusion-limiting layer 1915 may be disposed on top of the biometric layer 1914.

[0247] As described above, the counter electrode is an electrode that supplies (via current) or sinks the electrons necessary to sustain the electrochemical reaction at the working electrode. The number of counter electrode components can be increased in the form of a counter electrode array to increase the surface area so that the current-carrying capacity of the counter electrode does not limit the redox reaction of the working electrode. Therefore, in order to avoid the limitation of the current-carrying capacity, it may be desirable to have an excessive counter electrode area relative to the working electrode area. When the working electrode operates as an anode, the counter electrode functions as a cathode, and vice versa. Similarly, when an oxidation reaction occurs at the working electrode, a reduction reaction occurs at the counter electrode, and vice versa. Different from the working electrode or the reference electrode, the counter electrode can swing dynamically to the potential necessary to maintain the target redox reaction on the working electrode.

[0248] As shown in FIG. 19B, the counter electrode 1920 can include an electrode material 1922, similar to the electrode material 1912. For example, similar to the electrode material 1912, the electrode material 1922 in the counter electrode 1920 may include noble metals such as gold, platinum, palladium, iridium, carbon, doped diamond, and / or other suitable catalysts and inert materials.

[0249] In some variations, the counter electrode 1920 may have few or no additional layers on the electrode material 1922. However, in some variations, the counter electrode 1920 can benefit from increasing the surface area to increase the amount of current it can support. For example, the counter electrode material 1922 can be textured or otherwise roughened to increase the surface area of the electrode material 1922 to enhance the current supply or sink capacity. The counter electrode 1920 may include an electrode roughening layer 1927. The electrode roughening layer may include, for example, platinum black, which may increase the electrode surface as described above for some variations of the working electrode. However, in some variations of the counter electrode, the electrode roughening layer 1927 may be omitted.

[0250] In some variations, the counter electrode 1920 can include a diffusion limiting layer 1925 (e.g., disposed on the electrode). The diffusion limiting layer 1925 can be similar to the diffusion limiting layer 1915 described above with respect to FIG. 19A, for example. In some variations that include the diffusion limiting layer 1925, the counter electrode 1920 can further include a hydrophilic layer that provides a biocompatible interface, for example, to reduce foreign body response. The hydrophilic layer can be disposed on the diffusion limiting layer 1925.

[0251] In some variations, the counter electrode 1920 can include an electrode protection layer 1928 such as those described with reference to the working electrode. The electrode protection layer 1928 can be disposed on the electrode material 1922, or in variations that have an electrode roughening layer 1927, the electrode protection layer 1928, when provided, is disposed on the electrode roughening layer. In some variations, the diffusion limiting layer 1925 can be disposed on the electrode protection layer 1928. In some variations, the hydrophilic layer can be disposed on the diffusion limiting layer 1925.

[0252] As described above, the reference electrode functions to provide a reference potential to the system. That is, the potential at which the working electrode is biased is referenced to the reference electrode. A fixed or at least controlled potential relationship can be established between the working electrode and the reference electrode, and within practical limits, no current is supplied from or sunk into the reference electrode.

[0253] As shown in FIG. 19C, the reference electrode 1930 can include an electrode material 1932, similar to the electrode material 1912. In some variations, similar to the electrode material 1912, the electrode material 1932 of the reference electrode 1930 can include a metal salt or metal oxide that functions as a stable redox combined with a well-known electrode potential. For example, the metal salt may include, for example, silver-silver chloride (Ag / AgCl), and the metal oxide may include iridium oxide (IrOx / Ir2O3 / IrO2). In other variations, noble metal and inert metal surfaces can function as quasi-reference electrodes and can include gold, platinum, palladium, iridium, carbon, doped diamond, and / or other suitable catalysts and inert materials. Further, in some variations, the reference electrode 1930 may be roughened by texturing or other methods to enhance adhesion to any subsequent layer. Such a subsequent layer on the electrode material 1932 can include an electrode roughening layer 1937. In some variations, the electrode roughening layer 1937 may be omitted.

[0254] In some variations, the reference electrode 1930 may further include a redox pair layer 1936 that can include a surface-immobilized solid-state redox pair having a stable thermodynamic potential. For example, the reference electrode can operate at a standard thermodynamic potential that is stable with respect to the standard hydrogen electrode (SHE). High stability of the electrode potential can be achieved by using a redox system in which the concentration of each relevant component of the redox reaction is constant (e.g., buffered or saturated). For example, the reference electrode may include saturated Ag / AgCl (E = +0.197V vs. SHE) or IrOx (E = +0.177 vs. SHE, pH = 7.00) within the redox pair layer 1936. Other examples of the redox pair layer 1936 may include a suitable conductive polymer having dopant molecules as described in U.S. Patent Application Publication No. 2019 / 0309433, which is incorporated herein by reference in its entirety. In some variations, the reference electrode can be used as a half-cell for constructing a complete electrochemical cell.

[0255] In some modified forms, the reference electrode 1930 may include a diffusion limiting layer 1935 (e.g., disposed on the electrode 1932 and / or the redox pair layer 1936). The diffusion limiting layer 1935 may be the same as the diffusion limiting layer 1915 described above with respect to FIG. 19A, for example. In some modified forms including the diffusion limiting layer 1935, the reference electrode 1930 may further include a hydrophilic layer that provides a biocompatible interface, for example, to reduce foreign object response. The hydrophilic layer may be disposed on the diffusion limiting layer 1935.

[0256] In some modified forms, the reference electrode 1930 may include an electrode protection layer 1938 such as those described with reference to the working electrode and / or the counter electrode. The electrode protection layer 1938 may be disposed on the electrode material 1932, or in a modified form having an electrode roughening layer 1937, the electrode protection layer 1938, if provided, is disposed on the electrode roughening layer 1937.

[0257] In some modified forms, the electrode roughening layer 1937 is disposed on the electrode material 1932. An electrode protection layer 1938 is disposed on the electrode roughening layer 1937, and a redox pair layer 1936 is disposed on the electrode protection layer 1938. In some embodiments, the diffusion limiting layer 1935 is disposed on the redox pair layer 1936. In some modified forms, a hydrophilic layer may be disposed on the diffusion limiting layer 1935.

[0258] The foregoing description has used a specific nomenclature for purposes of explanation to provide a complete understanding of the invention. However, it will be apparent to those skilled in the art that specific details are not required to practice the invention. Accordingly, the foregoing description of specific embodiments of the invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to explain the principles of the invention and its practical application, thereby enabling those skilled in the art to utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.

[0259] Numbered embodiments for practicing the invention Notwithstanding the attached claims, the present disclosure describes the following numbered embodiments.

[0260] (1) A method of operating an analyte monitoring device configured to be inserted into a user's skin, the method comprising determining, by a controller of the analyte monitoring device, a source of a power-on event, the source of the power-on event being power received from a connection to a battery or an ambient power generation module; and transitioning the analyte monitoring device to an operating mode corresponding to the determined source of the power-on event, wherein when the determined source of the power-on event is a connection to a battery, the corresponding operating mode includes a startup mode, and when the source of the power-on event is power received from an ambient power generation module, the corresponding operating mode includes a reset mode.

[0261] (2) The analyte monitoring device according to (1), wherein the power-on event is the controller being powered on or the controller receiving a power-on signal.

[0262] (3) The determination includes determining whether the battery is connected to the controller based on a signal between the battery and the controller, and the method according to (1) or (2).

[0263] (4) The determination includes determining whether the analyte monitoring device has transitioned to an operable state, and the method according to any one of (1) to (3).

[0264] (5) Determining that the analyte monitoring device is in an operable state is based on data from one or more non-analyte sensors of the analyte monitoring device, and the data includes one or more of optical data, magnetic field data, accelerometer data, and capacitance data, and the method according to (4).

[0265] (6) The optical data includes ambient optical data received from an ambient light sensor of the analyte monitoring device, and the method according to (5).

[0266] (7) The transition of the analyte monitoring device to an operable state causes a signal to be generated in a phototransistor of the analyte monitoring device to a power connection circuit of the analyte monitoring device, and the signal closes a switch of the power connection circuit to couple the battery to the controller, and the method according to (6).

[0267] (8) Closing the switch of the power connection circuit further couples the battery to an analog front end of the analyte monitoring device, and the analog front end is configured to convert an analog current measurement value obtained by a microneedle array of the analyte monitoring device into a digital value, and the digital value indicates the analyte concentration, and the method according to (7).

[0268] (9) When it is determined that the analyte monitoring device is not in an operable state, the method according to (4) or (5) further includes determining whether the analyte monitoring device is disposed within a communication field.

[0269] (10) Determining that the analyte monitoring device is within the communication field is based on detecting the communication field based on a signal between the environmental power generation module and the controller, the method according to (9).

[0270] (11) The method according to (10), further comprising waiting for a predetermined period to receive a wireless transmission from a remote device.

[0271] (12) The method according to (11), further comprising applying a reconfiguration parameter and entering a power-off state in response to receiving the wireless transmission.

[0272] (13) The method according to (11) or (12), further comprising entering a power-off state in response to not receiving the wireless transmission.

[0273] (14) In response to not receiving the wireless transmission, enabling a timer and attempting to shut down, and determining whether the analyte monitoring device has transitioned to an operable state if it is determined that the shutdown has not been successful within the limited time of the timer, or entering a power-off state if it is determined that the shutdown has been successful within the limited time of the timer, the method according to any one of (11) to (13).

[0274] (15) The method according to (9) or (10), further comprising entering a power-off state in response to determining that the analyte monitoring device is not disposed within the communication field.

[0275] (16) In response to determining that the analyte monitoring device is not disposed within the communication field, enabling a timer and attempting to shut down, and determining whether the analyte monitoring device has transitioned to an operable state if it is determined that the shutdown has not been successful within the limited time of the timer, or entering a power-off state if it is determined that the shutdown has been successful within the limited time of the timer, the method according to any one of (9), (10), and (15).

[0276] (17) The startup mode is the method according to any one of (1) to (4), including the sequence from the idle mode to the operation mode.

[0277] (18) The method according to (17), further including shifting the analyte monitoring device from the idle mode to the operation mode in response to confirmation of the insertion event.

[0278] (19) The method according to (18), wherein the confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, current generated from an applied bias potential, and communication from an external device.

[0279] (20) An analyte monitoring device, comprising: a microneedle array inserted into the user's skin and configured to obtain an analog current measurement value; a battery; an ambient power generation module; and a controller configured to determine a source of a power-on event, wherein the source of the power-on event is a connection to the battery or power received from the ambient power generation module, and to shift the analyte monitoring device to an operation mode corresponding to the determined source of the power-on event. When the determined source of the power-on event is a connection to the battery, the corresponding operation mode includes a startup mode, and when the source of the power-on event is power received from the ambient power generation module, the corresponding operation mode includes a reset mode.

[0280] (21) The analyte monitoring device according to (20), wherein the power-on event is that the controller is powered on or the reception of a power-on signal by the controller.

[0281] (22) The analyte monitoring device according to (20) or (21), wherein the determination includes determining whether the battery is connected to the controller based on a signal between the battery and the controller.

[0282] (23) The determination includes determining whether the analyte monitoring device has shifted to an operable state, and the analyte monitoring device according to any one of (20) to (22).

[0283] (24) Determining that the analyte monitoring device is in an operable state is based on data from one or more non-analyte sensors of the analyte monitoring device, and the data includes one or more of optical data, magnetic field data, accelerometer data, and capacitance data, and the analyte monitoring device according to (23).

[0284] (25) The optical data includes ambient optical data received from an ambient light sensor of the analyte monitoring device, and the method according to (24).

[0285] (26) The transition of the analyte monitoring device to an operable state causes a signal to be generated in a phototransistor of the analyte monitoring device to a power connection circuit of the analyte monitoring device, and the signal closes a switch of the power connection circuit to couple a battery to a controller, and the analyte monitoring device according to (24) or (25).

[0286] (27) Closing the switch of the power connection circuit further couples the battery to an analog front end of the analyte monitoring device, and the analog front end is configured to convert an analog current measurement value obtained by a microneedle array of the analyte monitoring device into a digital value, and the digital value indicates an analyte concentration, and the analyte monitoring device according to (26).

[0287] (28) The controller is further configured to determine whether the analyte monitoring device is disposed within a communication field when it is determined that the analyte monitoring device is not in an operable state, and the analyte monitoring device according to (23) or (24).

[0288] The analyte monitoring device according to (28), wherein determining that the analyte monitoring device is within a communication field is based on detecting the communication field based on a signal between the environmental power generation module and the controller.

[0289] The analyte monitoring device according to (29), wherein the controller is further configured to wait for a predetermined period to receive a wireless transmission from a remote device.

[0290] The analyte monitoring device according to (30), wherein the controller is further configured to apply a reconfiguration parameter and enter a power-off state in response to receiving a wireless transmission.

[0291] The analyte monitoring device according to (30) or (31), wherein the controller is further configured to enter a power-off state in response to not receiving a wireless transmission.

[0292] The analyte monitoring device according to any one of (30) to (32), wherein the controller is further configured to, in response to not receiving a wireless transmission, activate a timer, attempt to shut down, and determine whether the analyte monitoring device has transitioned to an operable state if it is determined that the shutdown has not been successful within the limit time of the timer, or enter a power-off state if it is determined that the shutdown has been successful within the limit time of the timer.

[0293] The analyte monitoring device according to (28) or (29), wherein the controller is further configured to enter a power-off state in response to determining that the analyte monitoring device is not disposed within a communication field.

[0294] (35) In response to determining that the analyte monitoring device is not located within the communication field, the controller activates a timer, attempts to shut down, and determines whether the analyte monitoring device has transitioned to a usable state if it is determined that the shutdown has not been successful within the limit time of the timer, or enters a power-off state if it is determined that the shutdown has been successful within the limit time of the timer. The analyte monitoring device according to any one of (28), (29), and (34).

[0295] (36) The startup mode includes a sequence from the idle mode to the operating mode. The analyte monitoring device according to any one of (20), (21), (22), and (23).

[0296] (37) Further includes transitioning the analyte monitoring device from the idle mode to the operating mode in response to confirmation of an insertion event. The analyte monitoring device according to (36).

[0297] (38) The confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, current generated from an applied bias potential, and communication from an external device. The analyte monitoring device according to (37).

[0298] (39) A method of operating an analyte monitoring device configured to be inserted into a user's skin, the method comprising determining by a controller of the analyte monitoring device that a power-on event is a valid power-on event, where a valid power-on event includes a transition of the analyte monitoring device to a usable state or an intentional placement of the analyte monitoring device within the communication field, and after determining that the power-on event is a valid power-on event, transitioning the analyte monitoring device to a mode corresponding to each valid power-on event.

[0299] (40) The power-on event is that the controller is powered on or the controller receives a power-on signal, for the analyte monitoring device according to (39).

[0300] (41) The ready-to-use state is the pre-insertion state where the analyte monitoring device is ready to be applied to the user's skin, or the post-insertion state where the analyte monitoring device is inserted into the user's skin, for the method according to (39) or (40).

[0301] (42) Determining that the power-on event includes a valid power-on event includes determining whether the analyte monitoring device has transitioned to a ready-to-use state, and in response to the determination that the analyte monitoring device has not transitioned to a ready-to-use state, determining that the analyte monitoring device is intentionally placed within a communication field, for the method according to any one of (39) to (41).

[0302] (43) Determining includes determining whether the analyte monitoring device is in a ready-to-use state, where the ready-to-use state is the pre-insertion state or the post-insertion state, for the method according to any one of (39) to (42).

[0303] (44) Determining that the analyte monitoring device is in a ready-to-use state is based on data from one or more non-analyte sensors of the analyte monitoring device, where the data includes one or more of optical data, magnetic field data, accelerometer data, and capacitance data, for the method according to (43).

[0304] (45) The optical data includes ambient optical data received from an ambient light sensor of the analyte monitoring device, for the method according to (44).

[0305] (46) The transition of the analyte monitoring device to a ready-to-use state causes a signal to be generated in a phototransistor of the analyte monitoring device to the power connection circuit of the analyte monitoring device, where the signal closes a switch of the power connection circuit to couple power to the controller, for the method according to (45).

[0306] (47) Closing the switch of the power connection circuit further couples the power to the analog front end of the analyte monitoring device, and the analog front end is configured to convert the analog current measurement obtained by the micro-needle array of the analyte monitoring device into a digital value, and the digital value indicates the analyte concentration, as described in (46).

[0307] (48) The mode corresponding to the transition of the analyte monitoring device to the usable state includes the idle mode, as described in any one of (39)-(43).

[0308] (49) Further includes transitioning the analyte monitoring device from the idle mode to the operating mode in response to confirmation of the insertion event, as described in (48).

[0309] (50) The confirmation of the insertion event is based on one or more of the elapsed time, accelerometer data, current generated from the applied bias potential, and communication from an external device, as described in (49).

[0310] (51) Further includes determining whether the analyte monitoring device is intentionally placed within the communication field in response to determining that the analyte monitoring device is not in a usable state, as described in any one of (39)-(43) and (48).

[0311] (52) Determining that the analyte monitoring device is intentionally placed within the communication field includes detecting the communication field and receiving a wireless transmission from a remote device within a predetermined period, as described in (51).

[0312] (53) The wireless transmission includes reconfiguration parameters for the controller, as described in (52).

[0313] (54) The mode corresponding to the intentional placement within the communication field of the analyte monitoring device includes the reconfiguration mode, the method according to any one of (39)-(43), (48), and (51).

[0314] (55) The method according to (54), further comprising shifting the analyte monitoring device to the power-off mode in response to completion of the reconfiguration mode.

[0315] (56) An analyte monitoring device, comprising a microneedle array configured to be inserted into a user's skin and acquire analog current measurement values, and a controller configured to determine that a power-on event is a valid power-on event, where a valid power-on event includes a transition of the analyte monitoring device to a usable state or an intentional placement within the communication field of the analyte monitoring device, and after determining that the power-on event is a valid power-on event, shift the analyte monitoring device to a mode corresponding to each valid power-on event.

[0316] (57) The power-on event is that the controller is powered on or the reception of a power-on signal by the controller, for the analyte monitoring device according to (56).

[0317] (58) The usable state is a pre-insertion state where the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state where the analyte monitoring device is inserted into the user's skin, for the analyte monitoring device according to (56) or (57).

[0318] Determining that the power-on event includes a valid power-on event includes determining whether the analyte monitoring device has transitioned to a usable state, and in response to determining that the analyte monitoring device has not transitioned to a usable state, determining that the analyte monitoring device is intentionally placed within the communication field, the analyte monitoring device according to any one of (56) to (58).

[0319] (60) Determining includes determining whether the analyte monitoring device is in a usable state, where the usable state is a state before insertion or after insertion, the analyte monitoring device according to any one of (56) to (59).

[0320] (61) Determining that the analyte monitoring device is in a usable state is based on data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data, the analyte monitoring device according to (60).

[0321] (62) The optical data includes ambient optical data received from an ambient light sensor of the analyte monitoring device, the analyte monitoring device according to (61).

[0322] (63) The transition of the analyte monitoring device to a usable state causes a signal to be generated in a phototransistor of the analyte monitoring device to the power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple power to the controller, the analyte monitoring device according to (62).

[0323] (64) Closing the switch of the power connection circuit further couples power to an analog front end of the analyte monitoring device, the analog front end being configured to convert an analog current measurement value obtained by a micro-needle array of the analyte monitoring device into a digital value, the digital value indicating an analyte concentration, the analyte monitoring device according to (63).

[0324] (65) The mode corresponding to the transition of the analyte monitoring device to an operable state includes the idle mode, and the analyte monitoring device according to any one of (56) to (60).

[0325] (66) The controller is further configured to cause the analyte monitoring device to transition from the idle mode to the operating mode in response to confirmation of the insertion event, and the analyte monitoring device according to (65).

[0326] (67) The confirmation of the insertion event is based on one or more of the elapsed time, accelerometer data, current generated from the applied bias potential, and communication from an external device, and the analyte monitoring device according to (66).

[0327] (68) The controller is further configured to determine whether the analyte monitoring device is intentionally placed within the communication field in response to determining that the analyte monitoring device is not in an operable state, and the analyte monitoring device according to any one of (56) to (60) and (65).

[0328] (69) Determining that the analyte monitoring device is intentionally placed within the communication field includes detecting the communication field and receiving a wireless transmission from a remote device within a predetermined period, and the analyte monitoring device according to (68).

[0329] (70) The wireless transmission includes reconfiguration parameters for the controller, and the analyte monitoring device according to (69).

[0330] (71) The mode corresponding to the intentional placement of the analyte monitoring device within the communication field includes the reconfiguration mode, and the analyte monitoring device according to any one of (56) to (60), (65), and (68).

[0331] (72) The controller is further configured to cause the analyte monitoring device to transition to a power-off mode in response to completion of the reconfiguration mode, the analyte monitoring device according to (71).

[0332] (73) A method of operating an analyte monitoring device configured to be inserted into a user's skin, the method comprising, by a controller of the analyte monitoring device, determining that a power-on event is a valid power-on event by identifying whether the analyte monitoring device is in a pre-insertion state in which the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state in which the analyte monitoring device is inserted into the user's skin, and in response to determining that the power-on event is a valid power-on event, transitioning the analyte monitoring device to an idle mode.

[0333] (74) Identifying comprises identifying whether the analyte monitoring device is in one of a pre-insertion state in which the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state in which the analyte monitoring device is inserted into the user's skin, the method according to (73).

[0334] (75) Identifying whether the analyte monitoring device is in one of a pre-insertion state or a post-insertion state comprises obtaining data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data, the method according to (74).

[0335] (76) The optical data includes ambient light data received from an ambient light sensor of the analyte monitoring device, the method according to (75).

[0336] (77) Transitioning the analyte monitoring device to a usable state causes a phototransistor of the analyte monitoring device to generate a signal to the power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple power to the controller, the method according to (76).

[0337] Closing the switch of the power connection circuit further couples the power supply to the analog front end of the analyte monitoring device, and the analog front end is configured to convert the analog current measurement obtained by the micro-needle array of the analyte monitoring device into a digital value, and the digital value indicates the analyte concentration, the method described in (77).

[0338] (79) Further including shifting the analyte monitoring device from the idle mode to the operating mode in response to confirmation of the insertion event, the method described in (73) or (74).

[0339] (80) Confirming the insertion event is based on one or more of elapsed time, accelerometer data, current resulting from an applied bias potential, and communication from an external device, the method described in (79).

[0340] (81) An analyte monitoring device, comprising a micro-needle array configured to be inserted into a user's skin and acquire an analog current measurement, and a controller configured to determine whether the analyte monitoring device is in a usable state, thereby determining that the power-on event is a valid power-on event, and in response to determining that the power-on event is a valid power-on event, shifting the analyte monitoring device to the idle mode.

[0341] (82) Identifying includes identifying whether the analyte monitoring device is in one of a pre-insertion state where the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state where the analyte monitoring device is inserted into the user's skin, the analyte monitoring device described in (81).

[0342] Identifying whether the analyte monitoring device is in one of the pre-insertion state or the post-insertion state includes obtaining data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data, the analyte monitoring device described in (82).

[0343] (84) The optical data includes ambient optical data received from an ambient light sensor of the analyte monitoring device, the analyte monitoring device described in (83).

[0344] (85) Transitioning the analyte monitoring device to an operable state causes a signal to be generated in a phototransistor of the analyte monitoring device to a power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple power to a controller, the analyte monitoring device described in (84).

[0345] (86) Closing the switch of the power connection circuit further couples power to an analog front end of the analyte monitoring device, the analog front end being configured to convert an analog current measurement value obtained by a microneedle array of the analyte monitoring device into a digital value, the digital value indicating an analyte concentration, the analyte monitoring device described in (85).

[0346] (87) The controller is further configured to transition the analyte monitoring device from an idle mode to an operating mode in response to confirmation of an insertion event, the analyte monitoring device described in (81) or (82).

[0347] (88) Confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, current resulting from an applied bias potential, and communication from an external device, the analyte monitoring device described in (87).

[0348] (89) A sensor assembly for an analyte monitoring device, comprising a microneedle array configured to acquire an analog current measurement value, and an electronic device assembly including a power supply, an analog front end configured to convert the analog current measurement value into a digital value, where the digital value indicates the concentration of the analyte, an analog front end, a controller configured to process the digital value, and a power supply connection circuit including a switch configured to couple the power supply to the controller and the analog front end, and an optical detection circuit configured to generate a signal to the power supply connection circuit to close the switch in response to a trigger event, thereby establishing a connection between the power supply and the controller and between the power supply and the analog front end. The connection between the optical detection circuit and the power supply connection circuit is established when connecting the microneedle array and the electronic device assembly.

[0349] (90) The electronic device assembly further includes a first printed circuit board to which the power supply, the analog front end, the controller, the power supply connection circuit, and the optical detection circuit are coupled, and the microneedle array is coupled to a second printed circuit board. The sensor assembly according to (89).

[0350] (91) The optical detection circuit includes signal lines routed between the first circuit board and the second circuit board, and the connection between the microneedle array and the electronic device assembly closes the signal lines of the optical detection circuit. The sensor assembly according to (90).

[0351] (92) The optical detection circuit includes a phototransistor, and the trigger event includes exposure to ambient light. The sensor assembly according to (89) or (90).

[0352] (93) The electronic device assembly further includes a boost circuit coupled between the power supply connection circuit and the analog front end, and the boost circuit is configured to boost the voltage to the analog front end. The sensor assembly according to any one of (89), (90), and (92).

[0353] (94) The electronic device assembly further comprises at least one light emitting diode, the at least one light emitting diode being coupled to a boost circuit, the boost circuit being configured to boost the voltage to the at least one light emitting diode, the sensor assembly according to (93).

[0354] (95) The electronic device assembly further comprises a peripheral power switch, the peripheral power switch being configured to control the power delivery to the ambient light sensor, the controller controlling the brightness of the at least one light emitting diode based on the level of light detected by the ambient light sensor, the sensor assembly according to (94).

[0355] (96) The peripheral power switch is further configured to control the power delivery to one or more of the motion sensor and the output device, the sensor assembly according to (95).

[0356] (97) The micro needle array includes at least one micro needle, the at least one micro needle including a tapered distal portion having an insulated distal tip and an electrode on the surface of the tapered distal portion disposed proximal to the insulated distal tip, the sensor assembly according to any one of (89), (90), (92), and (93).

[0357] (98) The electrode is a working electrode configured to sense an analyte, the at least one micro needle comprising a biorecognition layer disposed on the working electrode, the biorecognition layer comprising biorecognition elements, the sensor assembly according to (97).

[0358] A method of operating an analyte monitoring device configured to be inserted into a user's skin, the method comprising: applying a first bias potential by an analog front end of the analyte monitoring device, the first bias potential being applied between a first working electrode and a reference point; measuring a current resulting as a first result at the first working electrode; applying a second bias potential by the analog front end, the second bias potential being applied between a second working electrode and the reference point; measuring a current resulting as a second result at the second working electrode; and transitioning the analyte monitoring device to an operating mode in which an operating bias potential is applied in response to a determination that at least one of the current resulting as the first result and the current resulting as the second result is within a predetermined threshold. The analyte monitoring device comprises a microneedle array, and the microneedle array comprises at least two working electrodes, a reference electrode, and a counter electrode, each disposed on a respective microneedle of the microneedle array.

[0359] (100) The reference point comprises a combined counter / reference electrode reference point, the combined counter / reference electrode reference point being connected to the counter input and the reference input of the analog front end. The method according to (99).

[0360] (101) Further comprising forming the combined counter / reference electrode reference point by closing a first switch between the counter input and the reference input and opening a second switch at the reference input before applying the first bias potential. The method according to (100).

[0361] (102) The transitioning comprises opening the first switch and closing the second switch. The method according to (101).

[0362] (103) In the operation mode, when the current resulting as the first result is within a predetermined threshold, applying an operating bias potential to the first working electrode; and when the current resulting as the second result is within a predetermined threshold, applying an operating bias potential to the second working electrode. The method according to any one of (99) or (100).

[0363] (104) The analyte monitoring device further includes a second counter electrode, and the second counter electrode is disposed on each micro needle of the micro needle array. The method according to any one of (99), (100), and (103).

[0364] (105) The counter electrode and the second counter electrode are short - circuited together and connected to the differential input of the analog front - end. The method according to (104).

[0365] (106) The first bias potential is below the operating bias potential, and the second bias potential is below the operating bias potential. The method according to any one of (99), (100), (103), and (104).

[0366] (107) A method of operating an analyte monitoring device configured to be inserted into a user's skin. The method includes applying a first bias potential by an analog front - end of the analyte monitoring device, the first bias potential being applied between the first working electrode and a reference point; measuring the current resulting as the first result at the first working electrode; in response to a determination that the current resulting as the first result is within a predetermined threshold, transitioning the analyte monitoring device to an operation mode in which an operating bias potential is applied; and in the operation mode, applying the operating bias potential to at least a second working electrode. The analyte monitoring device includes a micro needle array, and the micro needle array includes at least two working electrodes, a reference electrode, and a counter electrode, each being disposed on each micro needle of the micro needle array.

[0367] (108) The reference point comprises a combined counter electrode / reference electrode reference point, and the combined counter electrode / reference electrode reference point is connected to the differential input of the analog front end and the reference input of the analog front end, the method according to (107).

[0368] (109) Further comprising forming a combined counter electrode / reference electrode reference point by closing a first switch between the differential input and the reference input and opening a second switch at the reference input before applying the first bias potential, the method according to (108).

[0369] (110) Transitioning comprises opening the first switch and closing the second switch, the method according to (109).

[0370] (111) The analyte monitoring device further comprises a second counter electrode, and the second counter electrode is disposed on each micro-needle of the micro-needle array, the method according to (107) or (108).

[0371] (112) The counter electrode and the second counter electrode are shorted together and connected to the differential input of the analog front end, the method according to (111).

[0372] (113) The first bias potential is below the operating bias potential, the method according to any one of (107), (108), and (111).

Claims

1. A method of operating an analyte monitoring device configured to be inserted into a user's skin, comprising: determining, by a controller of the analyte monitoring device, a source of a power-on event, wherein the source of the power-on event is power received from a connection to a battery or an ambient power generation module; transitioning the analyte monitoring device to an operating mode corresponding to the determined source of the power-on event; wherein, when the determined source of the power-on event is the connection to the battery, the corresponding operating mode includes a startup mode; when the source of the power-on event is the power received from the ambient power generation module, the corresponding operating mode includes a reset mode.

2. The method of claim 1, wherein the power-on event is the controller being powered on or the controller receiving a power-on signal.

3. The method of claim 1, wherein determining comprises determining whether the battery is connected to the controller based on a signal between the battery and the controller.

4. The method of claim 1, wherein determining comprises determining whether the analyte monitoring device has transitioned to an operable state.

5. Determining that the analyte monitoring device is in the operable state is based on data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data.

6. The method of claim 5, wherein the optical data includes ambient light data received from an ambient light sensor of the analyte monitoring device.

7. The transition of the analyte monitoring device to the operable state causes a phototransistor of the analyte monitoring device to generate a signal to a power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple the battery to the controller.

8. Closing the switch of the power connection circuit further couples the battery to the analog front end of the analyte monitoring device, and the analog front end is configured to convert an analog current measurement value obtained by the micro-needle array of the analyte monitoring device into a digital value, and the digital value indicates an analyte concentration. The method according to claim 7.

9. The method according to claim 4, further comprising determining whether the analyte monitoring device is disposed within a communication field when it is determined that the analyte monitoring device is not in the usable state.

10. Determining that the analyte monitoring device is within the communication field is based on detecting the communication field based on a signal between the ambient power generation module and the controller. The method according to claim 9.

11. The method according to claim 10, further comprising waiting for a predetermined period to receive a wireless transmission from a remote device.

12. The method according to claim 11, further comprising applying a reconfiguration parameter and entering a power-off state in response to receiving the wireless transmission.

13. The method according to claim 11, further comprising entering a power-off state in response to not receiving the wireless transmission.

14. In response to not receiving the wireless transmission, activating a timer and attempting to shut down; Determining whether the analyte monitoring device has transitioned to a usable state when it is determined that shutdown has not been successful within the limit time of the timer, or Entering a power-off state when it is determined that shutdown has been successful within the limit time of the timer; The method according to claim 11, further comprising.

15. The method according to claim 9, further comprising entering a power-off state in response to determining that the analyte monitoring device is not disposed within the communication field.

16. In response to determining that the analyte monitoring device is not disposed within the communication field, Activating a timer and attempting to shut down; Determining whether the analyte monitoring device has transitioned to a usable state when it is determined that shutdown has not been successful within the limit time of the timer, or If it is determined that the shutdown has been successful within the limited time of the timer, enter the power-off state. The method according to claim 9, further comprising.

17. The method according to claim 1, wherein the startup mode includes a sequence from the idle mode to the operation mode.

18. The method according to claim 17, further comprising shifting the analyte monitoring device from the idle mode to the operation mode in response to confirmation of an insertion event.

19. The method according to claim 18, wherein the confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, current generated from an applied bias potential, and communication from an external device.

20. An analyte monitoring device, A micro-needle array inserted into the user's skin and configured to obtain an analog current measurement value, A battery, An ambient power generation module, A controller, Determining a source of a power-on event, wherein the source of the power-on event is a connection to the battery or power received from the ambient power generation module, Shifting the analyte monitoring device to an operation mode corresponding to the determined source of the power-on event, A controller configured to perform, Comprising, When the determined source of the power-on event is the connection to the battery, the corresponding operation mode includes a startup mode, An analyte monitoring device, wherein when the source of the power-on event is the power received from the ambient power generation module, the corresponding operation mode includes a reset mode.

21. The analyte monitoring device according to claim 20, wherein the power-on event is that the controller is powered on or the reception of a power-on signal by the controller.

22. The analyte monitoring device according to claim 20, wherein the determining includes determining whether the battery is connected to the controller based on a signal between the battery and the controller.

23. The analyte monitoring device according to claim 20, wherein the determining includes determining whether the analyte monitoring device has shifted to a usable state.

24. Determining that the analyte monitoring device is in the usable state is based on data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data, according to the analyte monitoring device of claim 23.

25. The method according to claim 24, wherein the optical data includes ambient light data received from an ambient light sensor of the analyte monitoring device.

26. The transition of the analyte monitoring device to the usable state causes a phototransistor of the analyte monitoring device to generate a signal to a power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple the battery to the controller, according to the analyte monitoring device of claim 24.

27. Closing the switch of the power connection circuit further couples the battery to an analog front end of the analyte monitoring device, the analog front end being configured to convert an analog current measurement value obtained by a micro-needle array of the analyte monitoring device into a digital value, the digital value indicating an analyte concentration, according to the analyte monitoring device of claim 26.

28. The controller is further configured to determine whether the analyte monitoring device is disposed within a communication field when it is determined that the analyte monitoring device is not in the usable state, according to the analyte monitoring device of claim 23.

29. Determining that the analyte monitoring device is within the communication field is based on detecting the communication field based on a signal between the environmental power generation module and the controller, according to the analyte monitoring device of claim 28.

30. The controller is further configured to wait for a predetermined period to receive a wireless transmission from a remote device, according to the analyte monitoring device of claim 29.

31. The controller is further configured to apply reconfiguration parameters and enter a power-off state in response to receiving the wireless transmission, according to the analyte monitoring device of claim 30.

32. The analyte monitoring device according to claim 30, wherein the controller is further configured to enter a power-off state in response to not receiving the wireless transmission.

33. The controller in response to not receiving the wireless transmission, activates a timer and attempts to shut down; when it is determined that the shutdown has not been successful within the limited time of the timer, determines whether the analyte monitoring device has transitioned to a usable state, or when it is determined that the shutdown has been successful within the limited time of the timer, enters a power-off state, and is further configured to perform the above, the analyte monitoring device according to claim 30.

34. The analyte monitoring device according to claim 28, wherein the controller is further configured to enter a power-off state in response to determining that the analyte monitoring device is not disposed within the communication field.

35. The controller, in response to determining that the analyte monitoring device is not disposed within the communication field, activates a timer and attempts to shut down; when it is determined that the shutdown has not been successful within the limited time of the timer, determines whether the analyte monitoring device has transitioned to a usable state, or when it is determined that the shutdown has been successful within the limited time of the timer, enters a power-off state, and is further configured to perform the above, the analyte monitoring device according to claim 28.

36. The analyte monitoring device according to claim 20, wherein the startup mode includes a sequence from an idle mode to an operation mode.

37. The analyte monitoring device according to claim 36, further comprising transitioning the analyte monitoring device from the idle mode to the operation mode in response to confirmation of an insertion event.

38. The analyte monitoring device according to claim 37, wherein the confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, current generated from an applied bias potential, and communication from an external device.

39. A method of operating an analyte monitoring device configured to be inserted into a user's skin, comprising It is to be determined by a controller of the analyte monitoring device that the power-on event is a valid power-on event, where the valid power-on event includes a transition to a usable state of the analyte monitoring device or an intentional placement within the communication field of the analyte monitoring device, and to make the determination. After determining that the power-on event is the valid power-on event, causing the analyte monitoring devices to transition to modes corresponding to the respective valid power-on events. A method including this.

40. The method according to claim 39, wherein the power-on event is that the controller is powered on or reception of a power-on signal by the controller.

41. The method according to claim 39, wherein the usable state is a pre-insertion state in which the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state in which the analyte monitoring device is inserted into the user's skin.

42. The determination that the power-on event includes a valid power-on event is determining whether the analyte monitoring device has transitioned to the usable state; in response to a determination that the analyte monitoring device has not transitioned to the usable state, determining that the analyte monitoring device is intentionally placed within the communication field. The method according to claim 39, including this.

43. The determination includes determining whether the analyte monitoring device is in the usable state, and the usable state is a pre-insertion state or a post-insertion state. The method according to claim 39.

44. Determining that the analyte monitoring device is in the usable state is based on data from one or more non-analyte sensors of the analyte monitoring device, and the data includes one or more of optical data, magnetic field data, accelerometer data, and capacitance data. The method according to claim 43.

45. The method according to claim 44, wherein the optical data includes ambient light data received from an ambient light sensor of the analyte monitoring device.

46. The transition of the analyte monitoring device to the available state causes a phototransistor of the analyte monitoring device to generate a signal to the power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple power to the controller, the method of claim 45.

47. Closing the switch of the power connection circuit further couples the power to an analog front end of the analyte monitoring device, the analog front end being configured to convert an analog current measurement obtained by a micro-needle array of the analyte monitoring device into a digital value, the digital value indicating an analyte concentration, the method of claim 46.

48. The mode corresponding to the transition of the analyte monitoring device to the available state includes an idle mode, the method of claim 39.

49. Further including transitioning the analyte monitoring device from the idle mode to an operating mode in response to confirmation of an insertion event, the method of claim 48.

50. The confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, current resulting from an applied bias potential, and communication from an external device, the method of claim 49.

51. Further including determining whether the analyte monitoring device is intentionally placed within a communication field in response to a determination that the analyte monitoring device is not in the available state, the method of claim 39.

52. Determining that the analyte monitoring device is intentionally placed within the communication field includes detecting the communication field, and receiving a wireless transmission from a remote device within a predetermined period, the method of claim 51.

53. The wireless transmission includes reconfiguration parameters for the controller, the method of claim 52.

54. The mode corresponding to the intentional placement of the analyte monitoring device within the communication field includes a reconfiguration mode, the method of claim 39.

55. Further including transitioning the analyte monitoring device to a power-off mode in response to completion of the reconfiguration mode, the method of claim 54.

56. An analyte monitoring device, A microneedle array configured to be inserted into a user's skin and obtain an analog current measurement value, A controller, Determining that the power-on event is a valid power-on event, wherein the valid power-on event includes a transition to a usable state of the analyte monitoring device or an intentional placement within the communication field of the analyte monitoring device, After determining that the power-on event is the valid power-on event, transitioning the analyte monitoring device to a mode corresponding to each said valid power-on event, A controller configured to perform, An analyte monitoring device comprising.

57. The analyte monitoring device according to claim 56, wherein the power-on event is that the controller is powered on or reception of a power-on signal by the controller.

58. The analyte monitoring device according to claim 56, wherein the usable state is a pre-insertion state in which the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state in which the analyte monitoring device is inserted into the user's skin.

59. Said determining that the power-on event includes a valid power-on event Determining whether the analyte monitoring device has transitioned to the usable state, In response to a determination that the analyte monitoring device has not transitioned to the usable state, determining that the analyte monitoring device is intentionally positioned within the communication field, The analyte monitoring device according to claim 56, comprising.

60. Said determining includes determining whether the analyte monitoring device is in the usable state, and the usable state is a pre-insertion state or a post-insertion state. The analyte monitoring device according to claim 56.

61. Determining that the analyte monitoring device is in the usable state is based on data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data. The analyte monitoring device according to claim 60.

62. The analyte monitoring device according to claim 61, wherein the optical data includes ambient optical data received from an ambient optical sensor of the analyte monitoring device.

63. The transition of the analyte monitoring device to the usable state causes a phototransistor of the analyte monitoring device to generate a signal to a power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple power to the controller, the analyte monitoring device according to claim 62.

64. Closing the switch of the power connection circuit further couples the power to an analog front end of the analyte monitoring device, the analog front end being configured to convert an analog current measurement value obtained by a micro needle array of the analyte monitoring device into a digital value, the digital value indicating an analyte concentration, the analyte monitoring device according to claim 63.

65. The mode corresponding to the transition of the analyte monitoring device to the usable state includes an idle mode, the analyte monitoring device according to claim 56.

66. The controller is further configured to transition the analyte monitoring device from the idle mode to an operating mode in response to confirmation of an insertion event, the analyte monitoring device according to claim 65.

67. The confirmation of the insertion event is based on one or more of an elapsed time, accelerometer data, a current resulting from an applied bias potential, and communication from an external device, the analyte monitoring device according to claim 66.

68. The controller is further configured to determine whether the analyte monitoring device is intentionally placed within the communication field in response to determining that the analyte monitoring device is not in the usable state, the analyte monitoring device according to claim 56. [[ID=I3]]

69. Determining that the analyte monitoring device is intentionally placed within the communication field includes detecting the communication field, and receiving a wireless transmission from a remote device within a predetermined period, the method according to claim 68.

70. The wireless transmission includes reconfiguration parameters for the controller, the analyte monitoring device according to claim 69.

71. The analyte monitoring device according to claim 56, wherein the mode corresponding to the intentional placement in the communication field of the analyte monitoring device includes a reconfiguration mode.

72. The analyte monitoring device according to claim 71, wherein the controller is further configured to shift the analyte monitoring device to a power-off mode in response to completion of the reconfiguration mode.

73. A method of operating an analyte monitoring device configured to be inserted into a user's skin, comprising: determining that a power-on event is a valid power-on event by identifying, by a controller of the analyte monitoring device, whether the analyte monitoring device is in a usable state; in response to determining that the power-on event is the valid power-on event, shifting the analyte monitoring device to an idle mode; A method comprising the steps of:

74. The method according to claim 73, wherein the identifying includes identifying whether the analyte monitoring device is in a pre-insertion state in which the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state in which the analyte monitoring device is inserted into the user's skin.

75. The method according to claim 74, wherein the identifying whether the analyte monitoring device is in the pre-insertion state or the post-insertion state includes obtaining data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data.

76. The method according to claim 75, wherein the optical data includes ambient light data received from an ambient light sensor of the analyte monitoring device.

77. The method according to claim 76, wherein the transition of the analyte monitoring device to the usable state causes a phototransistor of the analyte monitoring device to generate a signal to a power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple the power to the controller.

78. Closing the switch of the power connection circuit further couples the power supply to the analog front end of the analyte monitoring device, the analog front end being configured to convert an analog current measurement obtained by the micro-needle array of the analyte monitoring device into a digital value, the digital value indicating an analyte concentration, the method of claim 77.

79. The method of claim 73, further comprising transitioning the analyte monitoring device from the idle mode to an operating mode in response to confirmation of an insertion event.

80. The confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, current resulting from an applied bias potential, and communication from an external device, the method of claim 79.

81. An analyte monitoring device, A micro-needle array configured to be inserted into a user's skin and obtain an analog current measurement, A controller, Determining that a power-on event is a valid power-on event by identifying whether the analyte monitoring device is in a usable state, In response to determining that the power-on event is the valid power-on event, transitioning the analyte monitoring device to an idle mode, A controller configured to perform, An analyte monitoring device comprising.

82. The identifying includes identifying whether the analyte monitoring device is in one of a pre-insertion state in which the analyte monitoring device is ready to be applied to the user's skin or a post-insertion state in which the analyte monitoring device is inserted into the user's skin, the analyte monitoring device of claim 81.

83. The identifying whether the analyte monitoring device is in one of the pre-insertion state or the post-insertion state includes obtaining data from one or more non-analyte sensors of the analyte monitoring device, the data including one or more of optical data, magnetic field data, accelerometer data, and capacitance data, the analyte monitoring device of claim 82.

84. The optical data includes ambient light data received from an ambient light sensor of the analyte monitoring device, the analyte monitoring device of claim 83.

85. The transition of the analyte monitoring device to the usable state causes a signal to be generated in a phototransistor of the analyte monitoring device to a power connection circuit of the analyte monitoring device, the signal closing a switch of the power connection circuit to couple the power to the controller, the analyte monitoring device according to claim 84.

86. Closing the switch of the power connection circuit further couples the power to an analog front end of the analyte monitoring device, the analog front end being configured to convert an analog current measurement obtained by a micro-needle array of the analyte monitoring device into a digital value, the digital value indicating an analyte concentration, the analyte monitoring device according to claim 85.

87. The controller is further configured to transition the analyte monitoring device from the idle mode to an operating mode in response to confirmation of an insertion event, the analyte monitoring device according to claim 81.

88. The confirmation of the insertion event is based on one or more of elapsed time, accelerometer data, a current resulting from an applied bias potential, and communication from an external device, the analyte monitoring device according to claim 87.

89. A sensor assembly of an analyte monitoring device, A micro-needle array configured to obtain an analog current measurement, An electronic device assembly, A power supply, An analog front end configured to convert the analog current measurement into a digital value, the digital value indicating an analyte concentration, the analog front end, A controller configured to process the digital value, A power connection circuit comprising a switch configured to couple the power to the controller and the analog front end, A light detection circuit configured to generate a signal to the power connection circuit to close the switch in response to a trigger event, thereby establishing a connection between the power supply and the controller and between the power supply and the analog front end, An electronic device assembly comprising, Comprising, A sensor assembly, wherein a connection between the light detection circuit and the power connection circuit is established upon connection between the micro-needle array and the electronic device assembly.

90. The electronic device assembly further includes a first printed circuit board to which the power supply, the analog front end, the controller, the power connection circuit, and the optical detection circuit are coupled, and the micro needle array is coupled to a second printed circuit board. The sensor assembly according to claim 89.

91. The optical detection circuit includes signal lines routed between the first circuit board and the second circuit board, and the connection between the micro needle array and the electronic device assembly closes the signal lines of the optical detection circuit. The sensor assembly according to claim 90.

92. The optical detection circuit includes a phototransistor, and the trigger event includes exposure to ambient light. The sensor assembly according to claim 89.

93. The electronic device assembly further includes a boost circuit coupled between the power connection circuit and the analog front end, and the boost circuit is configured to boost the voltage to the analog front end. The sensor assembly according to claim 89.

94. The electronic device assembly further includes at least one light emitting diode, the at least one light emitting diode is coupled to the boost circuit, and the boost circuit is configured to boost the voltage to the at least one light emitting diode. The sensor assembly according to claim 93.

95. The electronic device assembly further includes a peripheral power switch, the peripheral power switch is configured to control power delivery to an ambient light sensor, and the controller controls the brightness of the at least one light emitting diode based on the level of light detected by the ambient light sensor. The sensor assembly according to claim 94.

96. The peripheral power switch is further configured to control power delivery to one or more of a motion sensor and an output device. The sensor assembly according to claim 95.

97. The micro needle array includes at least one micro needle, and the at least one micro needle has a tapered distal portion having an insulated distal tip, and an electrode on the surface of the tapered distal portion disposed proximal to the insulated distal tip. The sensor assembly according to claim 89.

98. The electrode is a working electrode configured to sense the analyte, the at least one microneedle includes a biorecognition layer disposed on the working electrode, and the biorecognition layer includes a biorecognition element, the sensor assembly according to claim 97.

99. A method of operating an analyte monitoring device configured to be inserted into a user's skin, comprising: applying a first bias potential by an analog front end of the analyte monitoring device, the first bias potential being applied between a first working electrode and a reference point; measuring a current resulting as a first result at the first working electrode; applying a second bias potential by the analog front end, the second bias potential being applied between a second working electrode and the reference point; measuring a current resulting as a second result at the second working electrode; responsive to a determination that at least one of the current resulting as the first result and the current resulting as the second result is within a predetermined threshold, transitioning the analyte monitoring device to an operating mode in which an operating bias potential is applied; comprising the analyte monitoring device comprises a microneedle array, the microneedle array comprises at least two working electrodes, a reference electrode, and a counter electrode, each disposed on a respective microneedle of the microneedle array.

100. The reference point comprises a combined counter / reference electrode reference point, the combined counter / reference electrode reference point being connected to a counter input and a reference input of the analog front end, the method according to claim 99.

101. Further comprising forming the combined counter / reference electrode reference point by closing a first switch between the counter input and the reference input and opening a second switch at the reference input before applying the first bias potential, the method according to claim 100.

102. The transitioning comprises opening the first switch and closing the second switch, the method according to claim 101.

103. In the operation mode, when the current resulting as the first result is within the predetermined threshold value, applying the operation bias potential to the first working electrode; when the current resulting as the second result is within the predetermined threshold value, applying the operation bias potential to the second working electrode; The method according to claim 99, further comprising.

104. The analyte monitoring device further includes a second counter electrode, and the second counter electrode is disposed on each micro needle of the micro needle array. The method according to claim 99.

105. The counter electrode and the second counter electrode are short-circuited together and connected to the differential input of the analog front end. The method according to claim 104.

106. The first bias potential is lower than the operation bias potential, and the second bias potential is lower than the operation bias potential. The method according to claim 99.

107. A method of operating an analyte monitoring device configured to be inserted into a user's skin, applying a first bias potential by an analog front end of the analyte monitoring device, the first bias potential being applied between a first working electrode and a reference point; measuring a current resulting as a first result at the first working electrode; in response to a determination that the current resulting as the first result is within a predetermined threshold value, transitioning the analyte monitoring device to an operation mode in which an operation bias potential is applied; in the operation mode, applying the operation bias potential to at least a second working electrode; including The analyte monitoring device includes a micro needle array, and the micro needle array includes at least two working electrodes, a reference electrode, and a counter electrode, each of which is disposed on each micro needle of the micro needle array. Method.

108. The reference point includes a combined counter electrode / reference electrode reference point, and the combined counter electrode / reference electrode reference point is connected to the differential input of the analog front end and the reference input of the analog front end. The method according to claim 107.

109. The method of claim 108, further comprising forming the combined counter / reference electrode reference point by closing a first switch between the counter input and the reference input and opening a second switch at the reference input before applying the first bias potential. **Claim 110** The method of claim 109, wherein transitioning comprises opening the first switch and closing the second switch. **Claim 111** The method of claim 107, wherein the analyte monitoring device further comprises a second counter electrode disposed on each micro-needle of the micro-needle array. **Claim 112** The method of claim 111, wherein the counter electrode and the second counter electrode are shorted together and connected to the counter input of the analog front end. **Claim 113** The method of claim 107, wherein the first bias potential is below the operating bias potential.

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