Methods and systems for sensing multiple analytes - Patents.com

Abstract

The device includes a multi-analyte sensor, a transimpedance amplifier, and a differential amplifier. The multi-analyte sensor includes a first working electrode, a second working electrode, a counter electrode, and a reference electrode. Each of the first working electrode and the second working electrode is configured to receive a signal indicative of the presence of a respective analyte. The counter electrode is a sum of each of the received signals of the first working electrode and the second working electrode. The transimpedance amplifier is configured to receive a first signal of the received signals from the first working electrode and a second signal of the received signals from the second working electrode. The transimpedance amplifier converts the first received signal and the second received signal to an output including a variable bias offset. The differential amplifier is configured to subtract the variable bias offset from the output.

Description

[Technical field]

[0001] The disclosed subject matter relates to systems and methods for sensing multiple analytes, such as sensors for monitoring analyte levels. [Background technology]

[0002] Some of these analyte sensors are equipped with powerful processors and operate using a constant power source, while others are designed to operate efficiently using little power. Active analyte sensors, including those used to monitor the level of an analyte, are one example of such an analyte sensor. The analyte sensor may include sensing hardware to detect a raw value of a signal that is determined to correlate with the level of the analyte. The analyte sensor may also be configured to perform on-device processing, for example, by applying algorithms and calibration parameters to the signal to convert the raw value into a level of the analyte that is useful for monitoring a patient's condition or useful for diagnosis and treatment. The analyte sensor may further determine patterns or trends in the level of the analyte in the patient. Such processed information may be provided to the patient or other interested parties for review. To increase efficiency, the components of the analyte sensor may be specialized for a particular processing function, but high specialization of the components may also increase the cost of the components used in the analyte sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2013 / 0150691 [Patent Document 2] US Patent Application Publication No. 2021 / 0204841 [Patent Document 3] International Publication No. 2018 / 136898 [Patent Document 4] International Publication No. 2019 / 236850 [Patent Document 5] International Publication No. 2019 / 236859 [Patent Document 6] International Publication No. 2019 / 236876 [Patent Document 7] US Patent Application Publication No. 2020 / 0196919 [Patent Document 8] US Patent Application Publication No. 2016 / 0331283 [Patent Document 9] US Patent Application Publication No. 2018 / 0235520 [Patent Document 10] US Patent Application Publication No. 2014 / 0171771 [Patent Document 11] US Patent Application Publication No. 2010 / 00230285 [Patent Document 12] US Patent Application Publication No. 2019 / 0274598 Summary of the Invention [Problem to be solved by the invention]

[0004] At least in part because the analyte sensor can be worn by a patient, e.g., attached to the patient's skin, the analyte sensor can be designed to operate for extended periods of time using an internal power source. When the internal power source is depleted, the analyte sensor can be discarded. Thus, an opportunity exists for systems and methods that can be embodied in and implemented by low power analyte sensors to reduce the production costs of the analyte sensor and increase the computational and power efficiency of the device while maintaining the ability of the analyte sensor to perform expected functions such as secure wireless communication, easy attachment and activation, and compatibility with a variety of receiving devices. [Means for solving the problem]

[0005] The objects and advantages of the disclosed subject matter will be set forth in the description which follows, and will be obvious from the description, or will be learned by practice of the disclosed subject matter. Additional advantages of the disclosed subject matter will be realized and attained by the methods and systems particularly pointed out in the description and claims hereof, as well as the drawings.

[0006] To achieve the above and other advantages in accordance with the objectives of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes an implantation system for use with an analyte sensor and a method of operation thereof.

[0007] In accordance with the disclosed subject matter, by way of example and not limitation, a device may include a multi-analyte sensor, a transimpedance amplifier, a differential amplifier, and a processor. The device may be embodied as an analyte sensing hardware. The multi-analyte sensor may be embodied as a dual analyte sensor. The multi-analyte sensor may include a first working electrode, a second working electrode, a counter electrode, and a reference electrode. Each of the first working electrode and the second working electrode may be configured to receive a signal indicative of the presence of a respective analyte. The analyte may include one or more of ketone, glucose, or lactate. The counter electrode may be a sum of the received signals of each of the first working electrode and the second working electrode. The transimpedance amplifier may be configured to receive a first signal of the received signals from the first working electrode and a second signal of the received signals from the second working electrode. The transimpedance amplifier may convert the received first signal and the second signal to an output including a variable bias offset. The received signal may be a current signal. The transimpedance amplifier may be further configured to convert the first current signal and the second current signal to an output voltage. The differential amplifier may be configured to subtract a variable bias offset from the output to generate a modified output including a variable residual. The processor may be configured to generate data indicative of the analyte value from the modified output. The processor may employ a calibration function configured to adjust the generated data based on the variable residual. The calibration function may be configured to adjust the generated data to remove the variable residual. The variable bias offset may be determined based on a first analyte measured by the first working electrode or a second analyte measured by the second working electrode. The differential amplifier may be further configured to calibrate out a bias-dependent residual and a common mode operational amplifier characteristic from the output to generate the modified output. The bias-dependent residual may be determined based on a two-point offset calibration for one of the first working electrode or the second working electrode. The common mode operational amplifier characteristic may be determined based on a three-point calibration.

[0008] According to the disclosed aspects, the device may further include an analog-to-digital converter, a communication module, and a negative-balanced bias amplifier. The analog-to-digital converter may be configured to convert the modified output to a digital output. Subtraction of the variable bias offset from the output may reduce the modified output to the range of the analog-to-digital converter. The communication module may be configured to process the digital output into a measurement result. The communication module may be separate from the device. The communication module may be further configured to provide the measurement result to a receiving device for display via wireless communication. The negative-balanced bias amplifier may be configured to subtract a predetermined voltage from the reference electrode to generate a first working electrode bias for biasing the first working electrode. The predetermined voltage may be determined based on a first analyte measured by the first working electrode or a second analyte measured by the second working electrode. The negative-balanced bias amplifier may be further configured to receive a reference signal from the reference electrode and a negative-balanced reference value. The device may be configured to detect a blood ketone level, a blood glucose level, a blood lactate level, or a level of other analytes.

[0009] In accordance with the disclosed subject matter, by way of example and not limitation, a device may include a multi-analyte sensor and an application specific integrated circuit. The device may be embodied as an analyte sensing hardware. The multi-analyte sensor may be embodied as a dual analyte sensor. The multi-analyte sensor may include a first working electrode, a second working electrode, a counter electrode, and a reference electrode. Each of the first working electrode and the second working electrode may be configured to receive a signal indicative of the presence of a respective analyte. The application specific integrated circuit may be configured to receive a first signal of the received signal from the first working electrode and a second signal of the received signal from the second working electrode. The application specific integrated circuit may set a first independent bias voltage for the first working electrode and a second independent bias voltage for the second working electrode. The application specific integrated circuit may generate data indicative of the analyte using the first independent bias voltage and the second independent bias voltage. The application specific integrated circuit may be configured to sense one or more signals below a threshold current specific to a particular analyte.

[0010] In accordance with the disclosed subject matter, by way of example and not limitation, a device may include a multi-analyte sensor, a first application specific integrated circuit, a second application specific integrated circuit, and a serial-peripheral interface (SPI) interface. The device may be embodied as an analyte sensing hardware. The multi-analyte sensor may be embodied as a dual analyte sensor. The multi-analyte sensor may include a first working electrode, a second working electrode, a counter electrode, and a reference electrode. Each of the first working electrode and the second working electrode may be configured to receive a signal indicative of the presence of a respective analyte. The first application specific integrated circuit may be configured to receive a first signal of the received signal from the first working electrode. The first application specific integrated circuit may set a first independent bias voltage for the first working electrode. The first application specific integrated circuit may be further configured to generate data indicative of the first analyte using the first independent bias voltage. The second application specific integrated circuit may be configured to receive a second signal of the received signal from the second working electrode. The second application specific integrated circuit can set a second independent bias voltage for the second working electrode. The second application specific integrated circuit can be further configured to generate data indicative of the second analyte with the second independent bias voltage. The SPI interface can be configured to individually receive communications from either the first application specific integrated circuit or the second application specific integrated circuit. The SPI interface can include one or more communication lines shared between the first application specific integrated circuit and the second application specific integrated circuit.

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to illustrate and provide a further understanding of the methods and systems of the disclosed subject matter and, together with the description, serve to explain the principles of the disclosed subject matter.

[0012] The details of the subject matter presented herein, both as to structure and operation, will be apparent from examination of the accompanying drawings, in which like reference numerals refer to like parts and in which: [Brief description of the drawings]

[0013] [Figure 1A] 1 is a system schematic diagram of a sensor applicator, a reader device, a monitor system, a network, and a remote system. [Figure 1B] FIG. 1 illustrates the operating environment of an exemplary analyte monitor system for use with the technology described herein. [Figure 2A] FIG. 2 is a block diagram illustrating an exemplary embodiment of a reader device. [Figure 2B] FIG. 2 is a block diagram illustrating an example data receiving device for communicating with a sensor in accordance with an example embodiment of the disclosed subject matter. [Figure 2C] FIG. 2 is a block diagram illustrating an exemplary embodiment of a sensor control device. [Figure 2D] FIG. 2 is a block diagram illustrating an exemplary embodiment of a sensor control device. [Figure 2E] FIG. 1 is a block diagram illustrating an exemplary analyte sensor in accordance with an exemplary embodiment of the disclosed subject matter. [Figure 3A] FIG. 1 is a close-up perspective view depicting an exemplary embodiment in which a user prepares a tray for assembly. [Figure 3B] 11 is a side view depicting an exemplary embodiment in which a user prepares the applicator device for assembly. [Figure 3C] FIG. 13 is a close-up perspective view depicting an exemplary embodiment in which a user inserts an applicator device into a tray during assembly. [Figure 3D] 13 is a close-up perspective view depicting an exemplary embodiment in which a user removes the applicator device from a tray during assembly. [Figure 3E] FIG. 13 is a close-up perspective view depicting an exemplary embodiment in which a patient applies a sensor using an applicator device. [Figure 3F] FIG. 1 is a close-up perspective view depicting an exemplary embodiment of a patient with a sensor attached and an applicator device used. [Figure 4A] 1 is a side view depicting an exemplary embodiment of an applicator device coupled to a cap. [Figure 4B] 1 is a side perspective view depicting an exemplary embodiment of an applicator device and cap separated. [Figure 4C] 1 is a perspective view depicting an exemplary embodiment of an applicator device and a distal end of an electronics housing. [Figure 4D] FIG. 1 is a top perspective view of an exemplary applicator device in accordance with the disclosed subject matter. [Figure 4E] FIG. 4E is a bottom perspective view of the applicator device of FIG. 4D. [Figure 4F] FIG. 4E is an exploded view of the applicator device of FIG. 4D. [Figure 4G] FIG. 4E is a side cutaway view of the applicator device of FIG. 4D. [Diagram 5] FIG. 1 is a close-up perspective view depicting an exemplary embodiment of a tray with a sterilization lid attached thereto. [Figure 6A] FIG. 2 is a close-up perspective cutaway view depicting an exemplary embodiment of a tray having a sensor delivery component. [Figure 6B] FIG. 2 is a close-up perspective view depicting a sensor delivery component. [Figure 7A] FIG. 2 illustrates an isometric exploded top view of an exemplary sensor control device. [Figure 7B] FIG. 2 illustrates an isometric exploded bottom view of an exemplary sensor control device. [Figure 8A] FIG. 13 is a diagram of an assembly of a body worn device including an integrated connector for a sensor assembly. [Figure 8B] FIG. 1 is a cross-sectional view of a body worn device including an integrated connector for a sensor assembly. [Figure 8C] FIG. 1 is a cross-sectional view of a body worn device including an integrated connector for a sensor assembly. [Figure 9A] 2D is a side view of an exemplary embodiment of the sensor applicator of FIG. 1A coupled with the cap of FIG. 2C. [Figure 9B] 2D is a cross-sectional side view of an exemplary embodiment of the sensor applicator of FIG. 1A coupled with the cap of FIG. 2C. [Figure 10A] FIG. 2 is an isometric view of another exemplary sensor control device. [Figure 10B] FIG. 2 is a side view of another exemplary sensor control device. [Figure 11A] 10A-10B. FIG. 10C is a cross-sectional side view showing a step-by-step assembly of a sensor applicator and the sensor control device of FIGS. [Figure 11B] 10A-10B. FIG. 10C is a cross-sectional side view showing a step-by-step assembly of a sensor applicator and the sensor control device of FIGS. [Figure 11C] 10A-10B. FIG. 10C is a cross-sectional side view showing a step-by-step assembly of a sensor applicator and the sensor control device of FIGS. [Figure 12A] 10A-10B , and FIG. 10C are cross-sectional side views illustrating the assembly and disassembly of an exemplary embodiment of the sensor applicator and sensor control device of FIG. [Figure 12B] 10A-10B , and FIG. 10C are cross-sectional side views illustrating the assembly and disassembly of an exemplary embodiment of the sensor applicator and sensor control device of FIG. [Figure 12C] 10A-10B , and FIG. 10C are cross-sectional side views illustrating the assembly and disassembly of an exemplary embodiment of the sensor applicator and sensor control device of FIG. [Figure 13A] 1 is a cross-sectional view depicting an exemplary embodiment of an applicator during a deployment stage. [Figure 13B] 1 is a cross-sectional view depicting an exemplary embodiment of an applicator during a deployment stage. [Figure 13C] 1 is a cross-sectional view depicting an exemplary embodiment of an applicator during a deployment stage. [Figure 13D] 1 is a cross-sectional view depicting an exemplary embodiment of an applicator during a deployment stage. [Figure 13E] 1 is a cross-sectional view depicting an exemplary embodiment of an applicator during a deployment stage. [Figure 13F] 1 is a cross-sectional view depicting an exemplary embodiment of an applicator during a deployment stage. [Figure 14] 1 is a graph illustrating an example of in vitro sensitivity of an analyte sensor. [Figure 15]1A-1C illustrate example operational states of a sensor in accordance with an example embodiment of the disclosed subject matter. [Figure 16] 1 illustrates an example operational and data flow for over-the-air programming of a sensor in accordance with the disclosed subject matter. [Figure 17] FIG. 2 illustrates an example data flow for secure data exchange between two devices in accordance with the disclosed subject matter. [Figure 18] FIG. 2 illustrates an example sensor and a receiver for communicating therewith in accordance with an example embodiment of the disclosed subject matter. [Figure 19] FIG. 2 illustrates functional blocks of a sensor according to an exemplary embodiment of the disclosed subject matter. [Figure 20] 1 illustrates an example interface between components of a sensor according to an example embodiment of the disclosed subject matter. [Figure 21] 1A-1C illustrate example functions of a measurement along with a thermistor of a sensor according to an example embodiment of the disclosed subject matter. [Figure 22] FIG. 2 illustrates an example function of an analog front end of a sensor according to an example embodiment of the disclosed subject matter. [Figure 23] FIG. 1 is a diagram of an example circuit for reading a value for an analyte sensor. [Figure 24] FIG. 1 is a diagram of an example circuit for reading a value for an analyte sensor. [Diagram 25] FIG. 2 is a diagram of an example circuit for a variable floating balance voltage generator. [Figure 26] FIG. 1 is a diagram of an example circuit having a sensor with a floating variable balanced voltage circuit in a measurement configuration. [Figure 27] FIG. 1 is a diagram of an example circuit having a sensor with a floating variable balanced voltage circuit in a calibration configuration. [Figure 28A] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Figure 28B] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Figure 29A] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Figure 29B]FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Diagram 30] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Diagram 31] FIG. 1 illustrates an example voltage characteristic of an operational amplifier for use with the disclosed subject matter. [Figure 32A] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Figure 32B] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Diagram 33] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. [Diagram 34] FIG. 1 is a diagram of an exemplary circuit having multiple analyte sensors. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Before describing the subject matter of the present invention in detail, it is to be understood that the disclosure is not limited to particular embodiments described, which can, of course, vary. Similarly, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the disclosure will be limited only by the claims.

[0015] As used throughout this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0016] The documents discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein should be construed as an admission that the present disclosure is not entitled to antedate such documents by virtue of prior disclosure. Further, the dates of the documents provided may be different from the actual publication dates, which may need to be independently confirmed.

[0017] In general, embodiments of the present disclosure include systems, devices, and methods for the use of an analyte sensor insertion applicator for use with an in vivo analyte monitor system. The applicator can be provided to a user in a sterile package with an electronics housing of a sensor control device enclosed therein. According to some embodiments, a structure such as a container separate from the applicator can also be provided to a user as a sterile package with a sensor module and a sharps module enclosed therein. A user can couple the sensor module to the electronics housing and couple the sharps to the applicator by an assembly process that includes inserting the applicator into the container in a specified manner. In other embodiments, the applicator, sensor control device, sensor module, and sharps module can be provided in a single package. The applicator can be used to position the sensor control device on the human body with the sensor in contact with the wearer's bodily fluids. The embodiments provided herein are improvements that reduce the likelihood of the sensor being improperly inserted or damaged or inducing an adverse physiological response. Other improvements and advantages are also provided. Various configurations of these devices are described in detail with examples only.

[0018] Additionally, many embodiments include an in vivo analyte sensor that is structurally configured such that at least a portion of the sensor is or can be positioned on the body of a user to obtain information regarding at least one analyte in the body. However, it should be noted that the embodiments disclosed herein can be used with in vivo analyte monitoring systems that incorporate extracorporeal functionality, as well as purely extracorporeal or ex vivo analyte monitoring systems, including completely non-invasive systems.

[0019] Additionally, for each and every embodiment of the methods disclosed herein, systems and devices having the functionality to perform each of these embodiments are within the scope of the present disclosure. For example, sensor control device embodiments are disclosed, which may have one or more sensors, analyte monitor circuitry (e.g., analog circuitry), memory (e.g., for storing instructions), power sources, communication circuitry, transmitters, receivers, processors, and / or controllers (e.g., for executing instructions) that may perform or facilitate the performance of any and all method steps. These sensor control device embodiments may be used to, and may have the functionality to, perform steps performed by the sensor control device from any and all of the methods described herein.

[0020] Additionally, the systems and methods provided herein can be used in conjunction with sensors used in analyte monitor systems, such as, but not limited to, wellness, fitness, dietary, research, information, or any purpose having analyte sensing over time. As used herein, "analyte sensor" or "sensor" can refer to any device capable of accepting sensor information from a user, including, by way of example, but not limited to, a temperature sensor, a blood pressure sensor, a pulse or heart rate sensor, a glucose level sensor, an analyte sensor, a physical activity sensor, a body movement sensor, or any other sensor for collecting physical or biometric information. Analytes measured by an analyte sensor can include, by way of example, but not limited to, glucose, ketones, lactate, oxygen, hemoglobin A1C, albumin, alcohol, alkaline phosphatase, alanine transaminase, aspartate aminotransferase, bilirubin, blood urea nitrogen, calcium, carbon dioxide, chloride, creatinine, hematocrit, lactate, magnesium, oxygen, pH, phosphorus, potassium, sodium, total protein, uric acid, and the like.

[0021] As mentioned above, some embodiments of systems, devices, and methods are described herein that provide improved assembly and use of dermal sensor insertion devices for use with in vivo analyte monitor systems. In particular, some embodiments of the present disclosure improve sensor insertion methods with respect to in vivo analyte monitor systems, and are specifically designed to prevent premature retraction of the insertion sharps during the sensor insertion process. Some embodiments include, for example, a dermal sensor insertion mechanism with a high firing rate and slow sharps retraction. In other embodiments, the sharps retraction mechanism can be motion-activated such that the sharps do not retract until the user pulls the applicator away from the skin. As a result, these embodiments can reduce the likelihood of premature withdrawal of the insertion sharps during the sensor insertion process, reduce the likelihood of incorrect sensor insertion, and reduce the likelihood of damaging the sensor during the sensor insertion process, to name a few advantages. Some embodiments of the present disclosure also allow for improved insertion sharps modules that take into account the small scale of dermal sensors and the relatively shallow insertion path present in the dermis of a subject. Additionally, some embodiments of the present disclosure are designed to prevent undesired axial and / or rotational movement of applicator components during sensor insertion. These embodiments can thus reduce the likelihood of capillary breakage resulting in instability of the positioned dermal sensor, irritation at the insertion site, damage to surrounding tissue, and contamination of skin fluids with blood, to name a few advantages. Additionally, to mitigate inaccurate sensor readings that may be caused by trauma at the insertion site, some embodiments of the present disclosure can reduce the distal needle penetration depth relative to the sensor tip during insertion.

[0022] However, before describing the above-mentioned aspects of the embodiments in detail, it is desirable to first describe examples of devices and their operation that may be present, for example, in an in vivo analyte monitor system, all of which may be used in the embodiments described herein.

[0023] There are various types of in vivo analyte monitor systems. A "continuous analyte monitor" system (or "continuous glucose monitor" system), for example, may transmit data continuously, e.g., automatically according to a schedule, from the sensor control device to the reader device without acknowledgment. As another example, an "intermittent analyte monitor" system (or "intermittent glucose monitor" system or simply "intermittent" system) may communicate data from the sensor control device using a scan by the reader device or, optionally, a near field communication (NFC) protocol or a radio frequency identification (RFID) protocol, etc. In vivo analyte monitor systems may operate without the need for finger stick calibration.

[0024] In vivo analyte monitor systems can be distinguished from "ex vivo" systems, which generally include a measurement device that contacts a biological sample outside the body (or "ex vivo") and has a port for accepting an analyte test strip that can carry a user's bodily fluid and be analyzed to determine the user's blood glucose level.

[0025] An in-vivo monitoring system may include a sensor that contacts a user's bodily fluid while positioned in the body and senses the level of an analyte contained therein. The sensor may be part of a sensor control device that resides on the user's body, the sensor control device including the electronics and power source that enable and control the analyte sensing. Sensor control devices and variations thereof may be referred to as "sensor control units," "body worn electronics" devices or units, "body worn" devices or units, or "sensor data communication" devices or units, to name a few.

[0026] An in-vivo monitoring system may include a device that accepts sensed analyte data from the sensor control device and processes and / or displays it to a user in any number of forms. This device and variations thereof may be referred to as a "handheld reader device," "reader device," (or simply "reader"), "handheld electronic device" (or simply "handheld"), "portable data processing" device or unit, "data receiver," "receiver" device or unit (or simply "receiver"), or "remote" device or unit, to name a few. Other devices, such as personal computers, have also been used with or incorporated into in-vivo or in-vivo monitoring systems.

[0027] FIG. 1A is a conceptual diagram illustrating an exemplary embodiment of an analyte monitor system 100 including a sensor applicator 150, a sensor control device 102, and a reader device 120. In this case, the sensor applicator 150 can be used to deliver the sensor control device 102 to a monitoring location on a user's skin where the sensor 110 is held stationary for a period of time by an adhesive patch 105. The sensor control device 102 can communicate with the reader device 120 through a communication path 144 using wired or wireless technology, as described in more detail in FIG. 2B and FIG. 2C. Exemplary wireless protocols include Bluetooth, Bluetooth low energy (such as BLE, BTLE, Bluetooth Smart), Near Field Communication (NFC), and others. A user can monitor applications installed in memory on the reader device 120 using a screen 122 and input 121, and the device's battery can be recharged using a power port 123. More detailed information regarding the reader device 120 is provided below with respect to FIG. 2A. The reader device 120 can communicate with a local computer system 170 through a communication path 141 using wired or wireless technology. The local computer system 170 can include one or more of a laptop, desktop, tablet, phablet, smart phone, set-top box, video game console, or other computing device, and the wireless communication can include any of several applicable wireless networking protocols, including Bluetooth, Bluetooth Low Energy (BTLE), Wi-Fi, or others. The local computer system 170 can communicate with the network 190 through a communication path 143 using wired or wireless technology as described above in a manner similar to the manner in which the reader device 120 can communicate with the network 190 through the communication path 142. The network 190 can be any of several networks, such as private and public networks, and local or wide area networks.The trusted computer system 180 may include a server, may provide authentication services and secure data storage, and may communicate with the network 190 through a communications path 144 using wired or wireless technology.

[0028] FIG. 1B illustrates an operating environment for an analyte monitor system 100a having the functionality to embody the techniques described herein. The analyte monitor system 100a may include a system comprised of components designed to provide monitoring of a parameter such as the level of an analyte in a human or animal body, or may enable other operations based on the configuration of the various components. As embodied herein, the system may include a low power analyte sensor 110, or simply a "sensor," worn by a user or attached to the body from which information is being collected. As embodied herein, the analyte sensor 110 may be a sealed, disposable device having a predetermined useful life (e.g., about 1 day, about 14 days, about 30 days, etc.). The sensor 110 may be applied to the skin of a user's body and may remain adherent for the duration of the sensor's life, or may be designed to remain functional when selectively removed and reapplied. The low power analyte monitor system 100a may further include a data reading device 120 or a general-purpose data receiving device 130 configured as described herein to facilitate retrieval and transmission of data, including analyte data, from the analyte sensor 110.

[0029] As embodied herein, the analyte monitoring system 100a may include software or firmware libraries or applications provided to a third party, for example, through a remote application server 150 or an application point-of-sale server 160, and embedded into a general-purpose hardware device 130, for example, a mobile phone, tablet, personal computing device, or other similar computing device capable of communicating with the analyte sensor 110 through a communications link. The general-purpose hardware may further include embedded devices, including, but not limited to, an insulin pump or insulin pen having an embedded library configured to communicate with the analyte sensor 110. Although the illustrated embodiment of the analyte monitoring system 100a includes only one of each of the illustrated devices, the present disclosure contemplates that the analyte monitoring system 100a may incorporate multiple respective components through which it interacts. By way of example and not limitation, as embodied herein, the data reading device 120 and / or the general-purpose data receiving device 130 may include multiple respective components. As embodied herein, multiple data receiving devices 130 may communicate directly with the sensor 110 as described herein. Additionally or alternatively, the data receiving devices 130 may communicate with auxiliary data receiving devices 130 to provide analyte data or a visual representation or analytical results thereof for auxiliary display to a user or other authorized interested party.

[0030] 2A is a block diagram illustrating an exemplary embodiment of a reader device configured as a smart phone. In this case, the reader device 120 may include a display 122, an input component 121, and a processing core 206 including a communication processor 222 coupled to a memory 223 and an application processor 224 coupled to a memory 225. Similarly, a separate memory 230, an RF transceiver 228 having an antenna 229, and a power source 226 having a power management module 238 may be included. Additionally, a multi-function transceiver 232 capable of communicating through Wi-Fi, NFC, Bluetooth, BTLE, and GPS using an antenna 234 may be included. As will be appreciated by those skilled in the art, these components are electrically and communicatively coupled in a manner to create a functional device.

[0031] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a data receiving device 120 shown in FIG. 2B for use with the subject matter of the present disclosure. The data receiving device 120 and associated general-purpose data receiving device 130 include components germane to the discussion of the analyte sensor 110 and its operation, and may include additional components. In certain embodiments, the data receiving device 120 and general-purpose data receiving device 130 may be or include components provided by third parties, and are not necessarily limited to including devices manufactured by the same manufacturer as the manufacturer of the sensor 110.

[0032] 2B, the data receiving device 120 includes an ASIC 4000 that includes a microcontroller 4010, a memory 4020, and storage 4030 communicatively coupled to a communication module 4040. Power for the components of the data receiving device 120 may be delivered by a power module 4050, which may include a rechargeable battery as embodied herein. The data receiving device 120 may further include a display 4070 to facilitate review of analyte data received from the analyte sensor 110 or other devices (e.g., the user device 140 or the remote application server 150). The data receiving device 120 may include separate user interface components (such as, for example, physical keys, a light sensor, a microphone, etc.).

[0033] The communication module 4040 may include a BLE module 4041 and an NFC module 4042. The data receiving device 120 may be configured to wirelessly couple with the analyte sensor 110 and send commands to and receive data from the analyte sensor 110. As embodied herein, the data receiving device 120 may be configured to operate as an NFC scanner and a BLE endpoint through a particular module (e.g., the BLE module 4042 or the NFC module 4043) of the communication module 4040 with respect to the analyte sensor 110 described herein. For example, the data receiving device 120 may issue commands to the analyte sensor 110 (e.g., an activation command for a data broadcast mode of the sensor, a pairing command to identify the data receiving device 120) using a first module of the communication module 4040 and send and receive data to and from the analyte sensor 110 using a second module of the communication module 4040. The data receiving device 120 may be configured for communication with the user device 140 through a universal serial bus (USB) module 4045 of the communication module 4040.

[0034] As another example, the communication module 4040 may include, for example, a cellular radio module 4044. The cellular radio module 4044 may include one or more radio transceivers for communicating with a broadband cellular network, including, but not limited to, third generation (3G), fourth generation (4G), and fifth generation (5G) networks. Additionally, the communication module 4040 of the data receiving device 120 may include a Wi-Fi radio module 4043 for communicating with a wireless local area network according to one or more of the IEEE 802.11 standards (e.g., 802.11a, 802.11b, 802.11g, 802.11n (aka Wi-Fi 4), 802.11ac (aka Wi-Fi 5), 802.11ax (aka Wi-Fi 6)). Using the cellular wireless module 4044 or the Wi-Fi wireless module 4043, the data receiving device 120 can communicate with a remote application server 150 to receive analyte data or provide updates or input received from a user (e.g., through one or more user interfaces). Although not illustrated, the communications module 5040 of the analyte sensor 120 can also include a cellular wireless module or a Wi-Fi wireless module.

[0035] As embodied herein, the on-board storage 4030 of the data receiving device 120 can store the analyte data received from the analyte sensor 110. Additionally, the data receiving device 120, the general-purpose data receiving device 130, or the user device 140 can be configured to communicate over a wide area network with a remote application server 150. As embodied herein, the analyte sensor 110 can provide data to the data receiving device 120 or the general-purpose data receiving device 130. The data receiving device 120 can transmit these data to the user computing device 140. Additionally, the user computing device 140 (or the general-purpose data receiving device 130) can transmit these data to the remote application server 150 for processing and analysis.

[0036] As embodied herein, the data receiving device 120 may further include sensing hardware 4060 similar to or extended from the sensing hardware 5060 of the analyte sensor 110. In certain embodiments, the data receiving device 120 may be configured to interface with the analyte sensor 110 and act based on analyte data received therefrom. As an example, where the analyte sensor 110 is a glucose sensor, the data receiving device 120 may be or include an insulin pump or an insulin injection pen. In conjunction therewith, the replaceable device 130 may adjust the insulin dosage to the user based on the glucose value received from the analyte sensor.

[0037] 2C and 2D are block diagrams illustrating an exemplary embodiment of a sensor control device 102 having an analyte sensor 110 and sensor electronics 160 that may have most of the processing functionality for rendering final result data suitable for display to a user. FIG. 2C shows a single semiconductor chip 161 that may be a custom application specific integrated circuit (ASIC). Within the ASIC 161, certain high level functional units are shown including an analog front end (AFE) 162, a power management (or control) circuit 164, a processor 166, and a communication circuit 168 (which may be embodied as a transmitter, receiver, transceiver, passive circuitry, or other communication protocol). In this embodiment, both the AFE 162 and the processor 166 are used as analyte monitor circuitry, although in other embodiments, either circuitry may perform the analyte monitor function. The processor 166 may include one or more processors, microprocessors, controllers, and / or microcontrollers, each of which may be a separate chip or distributed among (and be part of) several different chips.

[0038] Also included within the ASIC 161 is a memory 163, which may be shared by the various functional units present within the ASIC 161 or may be distributed among two or more of these functional units. The memory 163 may be a separate chip. The memory 163 may be a volatile and / or non-volatile memory. In this embodiment, the ASIC 161 is coupled to a power source 170, which may be a coin cell battery or the like. The AFE 162 interfaces with the in-vivo analyte sensor 110 to accept measurement data therefrom and output these data in digital type to a processor 166, which further processes these data to provide final result glucose individual values ​​and glucose trend values, etc. These data may then be provided to a communication circuit 168 for transmission through an antenna 171, for example, to a reader device 120 (not shown), where only minimal additional processing by a resident software application is required to display the data.

[0039] 2D is similar to FIG. 2C, but includes two separate semiconductor chips 162 and 174, which may be packaged together or separately. In this case, the AFE 162 resides on the ASIC 161. The processor 166 is integrated with the power management circuit 164 and the communication circuit 168 on the chip 174. The AFE 162 includes memory 163, and the chip 174 includes memory 165, which may be isolated or distributed therein. In one exemplary embodiment, the AFE 162 is combined with the power management circuit 164 and the processor 166 on one chip, while the communication circuit 168 is on a separate chip. In another exemplary embodiment, both the AFE 162 and the communication circuit 168 are on one chip, and the processor 166 and the power management circuit 164 are on another chip. It should be noted that other chip combinations are possible, including three or more chips each performing a separate function as described, or each sharing one or more functions to achieve fail-safe redundancy.

[0040] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of an analyte sensor 110 for use with the subject matter of the present disclosure, as shown in Figure 2E, which illustrates a block diagram of an exemplary analyte sensor 110 according to an exemplary embodiment consistent with the security architecture and communication schemes described herein.

[0041] As embodied herein, the analyte sensor 110 can include an application specific integrated circuit ("ASIC") 5000 communicatively coupled to a communication module 5040. The ASIC 5000 can include a microcontroller core 5010, an on-board memory 5020, and a storage memory 5030. The storage memory 5030 can store data used for authentication and encryption security architecture. The storage memory 5030 can store programming instructions for the sensor 110. As embodied herein, certain communication chipsets (e.g., NFC transceiver 5025) can be embedded within the ASIC 5000. The ASIC 5000 can receive power from a power module 5050, such as an on-board battery, or from an NFC pulse. The storage memory 5030 of the ASIC 5000 can be programmed to include information such as an identifier for the sensor 110 for identification and tracking purposes. The storage memory 5030 can be programmed with configuration or calibration parameters for use by the sensor 110 and its various components. The storage memory 5030 may include rewriteable memory or one-time programming (OTP) memory. The storage memory 5030 may be updated using techniques described herein to extend the usefulness of the sensor 110.

[0042] As embodied herein, the communication module 5040 of the sensor 100 may be or include one or more modules for supporting the analyte sensor 110 to communicate with other devices in the analyte monitoring system 100. By way of example only and not limitation, the exemplary communication module 5040 may include a Bluetooth Low Energy ("BLE") module 5041, where Bluetooth Low Energy ("BLE") is used throughout this disclosure to refer to a short-range communication protocol optimized for easy Bluetooth device pairing for end users. The communication module 5040 may transmit and receive data and instructions by interacting with a similarly capable communication module in the data receiving device 120 or user device 140. The communication module 5040 may include additional or alternative chipsets for use with similar short-range communication schemes such as, for example, IEEE 802.15 protocols, personal area networks according to IEEE 802.11 protocols, infrared communications according to the Infrared Data Association (IrDA) standard.

[0043] To perform its functions, the sensor 100 may further include sensing hardware 5060 appropriate for those functions. As embodied herein, the sensing hardware 5060 may include an analyte sensor positioned transcutaneously or subcutaneously in contact with the subject's bodily fluid. The analyte sensor may generate sensor data including a value corresponding to a level of one or more analytes present in the bodily fluid.

[0044] The components of the sensor control device 102 are available to the user in multiple packages that require final assembly by the user prior to delivery to the appropriate user location. Figures 3A-3D depict an exemplary embodiment of a user assembly process for the sensor control device 102 that includes preparation of separate components before combining the components to prepare the sensor for delivery. Figures 3E-3F depict an exemplary embodiment of delivery of the device 102 to an appropriate user location by selecting an appropriate delivery location and attaching the sensor control device 102 to the location.

[0045] 3A is a close-up perspective view depicting an exemplary embodiment in which a user provides a container 810, in this case configured as a tray for the assembly process (although other packaging can be used). The user can accomplish this preparation by removing the lid 812 from the tray 810 to expose the platform 808, for example, by peeling the non-adhered portion of the lid 812 from the tray 810 such that the adhered portion of the lid 812 is removed. Removal of the lid 812 can be as appropriate in various embodiments as long as the platform 808 is sufficiently exposed within the tray 810. The lid 812 can then be set aside.

[0046] 3B is a side view depicting an exemplary embodiment in which a user prepares applicator device 150 for assembly. Applicator device 150 may be provided in a sterile package sealed by cap 708. Preparing applicator device 150 may include disconnecting housing 702 from cap 708 to expose sheath 704 (FIG. 3C). This disconnection may be accomplished by unscrewing (or otherwise detaching) cap 708 from housing 702. Cap 708 may then be set aside.

[0047] 3C is a close-up perspective view depicting an exemplary embodiment in which a user inserts applicator device 150 into tray 810 during assembly. Initially, a user may insert sheath 704 into platform 808 inside tray 810 after housing orientation feature 1302 (or slot or recess) and tray orientation feature 924 (abutment or detent) are aligned. Inserting sheath 704 into platform 808 temporarily unlocks sheath 704 from housing 702, and also temporarily unlocks platform 808 from tray 810. At this stage, removal of applicator device 150 from tray 810 will result in the same condition as before the initial insertion of applicator device 150 into tray 810 (i.e., the process can be reversed or interrupted at this point and repeated without further consequences).

[0048] During distal advancement of the housing 702, the sheath 704 maintains its position relative to the housing 702 within the platform 808 and can mate with the platform 808 to advance the platform 808 distally relative to the tray 810. This step unlocks and collapses the platform 808 within the tray 810. The sheath 704 contacts and disconnects a locking feature (not shown) within the tray 810, thereby unlocking the sheath 704 from the housing 702 and preventing it from moving (relatively) while the housing 702 advances the platform 808 distally. At the end of advancement of the housing 702 and platform 808, the sheath 704 is permanently unlocked from the housing 702. At the end of distal advancement of the housing 702, the tip and sensor (not shown) within the tray 810 can mate with the electronics housing (not shown) within the housing 702. The operation and interaction of applicator device 150 and tray 810 is described in further detail below.

[0049] 3D is a close-up perspective view depicting an exemplary embodiment in which a user removes applicator device 150 from tray 810 during assembly. A user can remove applicator 150 from tray 810 by advancing housing 702 proximally relative to tray 810, or by other movement that has the same end effect as decoupling applicator 150 and tray 810. Applicator device 150 is removed with sensor control device 102 (point, sensor, electronics) (not shown) fully assembled therein and positioned for delivery.

[0050] 3E is a close-up perspective view depicting an exemplary embodiment in which a patient uses applicator device 150 to apply sensor control device 102 to a target area of ​​skin, for example on the abdomen or other suitable location. Advancing housing 702 causes sheath 704 therein to collapse distally, applying the sensor to the target location such that an adhesive layer on the bottom surface of sensor control device 102 adheres to the skin. The tip automatically retracts upon fully advancing housing 702, while the sensor (not shown) is left in place to measure the level of the analyte.

[0051] 3F is a close-up perspective view depicting an exemplary embodiment of a patient with the sensor control device 102 in an application position. The user can then remove the applicator 150 from the application site.

[0052] 3A-3F and elsewhere herein, may result in a reduction or elimination of the possibility of accidental damage, permanent deformation, or incorrect assembly of applicator components as compared to prior art systems. Because the applicator housing 702 directly engages the platform 808 while the sheath 704 is unlocked, rather than indirect engagement through the sheath 704, the relatively angular configuration between the sheath 704 and the housing 702 does not result in damage or permanent deformation of the arms or other components. The likelihood of a relatively high force being required during assembly (as with conventional devices) is reduced, thereby reducing the possibility of user assembly failure.

[0053] FIG 4A is a side view depicting an exemplary embodiment of applicator device 150 coupled to a screw cap 708. This view is an example of how applicator 150 is shipped and received by a user prior to assembly with a sensor by the user. FIG 4B is a side perspective view depicting applicator 150 and cap 708 after they have been separated. FIG 4C is a perspective view depicting an exemplary embodiment of the distal end of applicator device 150 with electronics housing 706 and adhesive patch 105 removed from the positions they would have been maintained within sensor carrier 710 of sheath 704 when cap 708 was in place.

[0054] For purposes of illustration and not limitation, and with reference to Figures 4D-4G, the applicator device 20150 can be provided to a user as a single, integral assembly. Figures 4D and 4E provide perspective top and bottom views, respectively, of the applicator device 20150, Figure 4F provides an exploded view of the applicator device 20150, and Figure 4G provides a side cutaway view. These perspective views illustrate how the applicator 20150 is shipped and received by a user. The exploded and cutaway views show the components of the applicator device 20150. The applicator device 20150 can include a housing 20702, a gasket 20701, a sheath 20704, a tip carrier 201102, a spring 205612, a sensor carrier 20710 (also referred to as a "puck carrier"), a tip hub 205014, a sensor control device (also referred to as a "puck") 20102, an adhesive patch 20105, a desiccant 20502, a cap 20708, a serial label 20709, and an unopened proof feature 20712. When a user receives the package, only the housing 20702, the cap 20708, the unopened proof feature 20712, and the label 20709 are visible. The tamper evident feature 20712 may be, for example, a sticker coupled to each of the housing 20702 and the cap 20708, and may be, for example, irreparably damaged by separating the housing 20702 and the cap 20708, thereby indicating to the user that the housing 20702 and the cap 20708 may have been previously separated. These features are described in more detail below.

[0055] FIG. 5 shows an exemplary embodiment of a tray 810 having a removably coupled sterilization lid 812, in a proximal perspective view that may represent how the package is shipped to a user and received by the user prior to assembly.

[0056] 6A is a close-up perspective cutaway view depicting the sensor delivery components within a tray 810. A platform 808 is slidably coupled within the tray 810. A desiccant 502 is fixed relative to the tray 810. A sensor module 504 is mounted within the tray 810.

[0057] 6B is a close-up perspective view depicting the sensor module 504 in greater detail, where the retention arm extension 1834 of the platform 808 releasably secures the sensor module 504 in place. The module 2200 is coupled with the connector 2300, the tine module 2500, and the sensor (not shown) so that they can be detached from one another as the sensor module 504 during assembly.

[0058] Referring back briefly to FIG. 1 and FIG. 3A-3G, in a two-piece architecture system, the sensor tray 202 and the sensor applicator 102 are provided to the user as separate packages, thus requiring the user to unpack each package and ultimately assemble the system. In some applications, these separate sealed packages allow the sensor tray 202 and the sensor applicator 102 to be sterilized in separate sterilization processes that are specific to the contents of each package and incompatible with the contents of other packages. More specifically, the sensor tray 202, including the plug assembly 207, including the sensor 110 and the sharps 220, can be sterilized using radiation sterilization, such as electron beam (or "e-beam") illumination. Suitable radiation sterilization processes include, but are not limited to, electron beam (e-beam) illumination, gamma ray illumination, x-ray illumination, or any combination thereof. However, radiation sterilization may damage electrical components positioned within the electronics housing of the sensor control device 102. As a result, if the sensor applicator 102, including the electronics housing of the sensor control device 102, needs to be sterilized, it can be sterilized by another method, such as gas chemical sterilization, for example with ethylene oxide. However, gas chemical sterilization may damage enzymes or other chemical and biological agents contained on the sensor 110. Due to this sterilization incompatibility, the sensor tray 202 and the sensor applicator 102 are typically sterilized in separate sterilization processes and then packaged separately, thereby requiring the user to ultimately assemble the components for use.

[0059] 7A and 7B are exploded top and bottom views, respectively, of a sensor control device 3702 according to one or more embodiments. The shell 5006 and the mount 5008 act as opposing clamshell halves that enclose or otherwise substantially encapsulate various electronic components of the sensor control device 3702. As shown, the sensor control device 3702 can include a printed circuit board assembly (PCBA) 3802 including a printed circuit board (PCB) 3804 having a number of electronic modules 3806 coupled thereto. Exemplary electronic modules 3806 include, but are not limited to, resistors, transistors, capacitors, inductors, diodes, and switches. Conventional sensor control devices typically stack PCB components on only one side of the PCB. In contrast, the PCB components 3806 in the sensor control device 3702 can be distributed around the surface area of ​​both sides (i.e., top and bottom) of the PCB 3804.

[0060] In addition to the electronic module 3806, the PCBA 3802 may further include a data processing unit 3808 mounted on the PCB 3804. The data processing unit 3808 may include, for example, an application specific integrated circuit (ASIC) configured to perform one or more functions or routines related to the operation of the sensor control device 3702. More specifically, the data processing unit 3808 may be configured to perform data processing functions, where such functions may include, but are not limited to, filtering and encoding a plurality of data signals each corresponding to a sampled analyte level of a user. The data processing unit 3808 may further include or otherwise communicate with an antenna for communicating with the reader device 106 (FIG. 1).

[0061] A battery opening 3810 may be defined within the PCB 3804 and sized to receive and seat a battery 3812 configured to power the sensor control device 3702. An axial battery contact 3814a and a radial battery contact 3814b may be coupled to the PCB 3804 and may extend into the battery opening 3810 to facilitate transfer of power from the battery 3812 to the PCB 3804. As the names suggest, the axial battery contact 3814a may be configured to provide axial contact to the battery 3812, while the radial battery contact 3814b may provide radial contact to the battery 3812. Positioning the battery 3812 within the battery opening 3810 with the battery contacts 3814a, 3814b helps reduce the height H of the sensor control device 3702, thereby allowing the PCB 3804 to be centrally positioned and its components to be distributed on both sides (i.e., top and bottom). This also helps facilitate providing corner surfaces 3718 on the electronics housing 3704 .

[0062] The sensor 3716 may be centrally located with respect to the PCB 3804 and may include a tail 3816, a flag 3818, and a neck 3820 interfacing the tail 3816 and the flag 3818. The tail 3816 may extend through a central opening 3720 in the mount 3708 and be configured to be transcutaneously received beneath the skin of a user. Additionally, the tail 3816 may have an enzyme or other chemical agent included thereon to help facilitate analyte monitoring.

[0063] The flag 3818 may include a generally flat surface having one or more sensor contacts 3822 (three shown in FIG. 7B ) positioned thereon. The sensor contacts 3822 may be configured to align with and engage one or more corresponding circuit contacts 3824 (three shown in FIG. 7A ) provided on the PCB 3804. In some embodiments, the sensor contacts 3822 may include a carbon-impregnated polymer printed or otherwise digitally applied to the flag 3818. Conventional sensor control devices typically include a connector made of silicone rubber that encapsulates one or more flexible carbon-impregnated polymer modules that serve as conductive contacts between the sensor and the PCB. In contrast, the sensor contacts 3822 of the present disclosure provide a direct connection between the sensor 3716 and the PCB 3804, thereby eliminating the need for a prior art connector and advantageously reducing the height H. Furthermore, by eliminating the flexible carbon-impregnated polymer modules, significant circuit resistance is eliminated, thus improving circuit conductivity.

[0064] The sensor control device 3702 may further include a compliant member 3826 that may be positioned to be sandwiched between the flag 3818 and an inner surface of the shell 3706. More specifically, when the shell 3706 and the mount 3708 are assembled together, the compliant member 3826 may be configured to provide a passive biasing load against the flag 3818 that urges the sensor contacts 3822 into continuous engagement with the corresponding circuit contacts 3824. In the illustrated embodiment, the compliant member 3826 is a resilient O-ring, but it is contemplated that the compliant member 3826 may instead include any other type of biasing device or function, such as a compression spring or the like, without departing from the scope of the present disclosure.

[0065] The sensor control device 3702 may further include one or more electromagnetic shields, shown as a first shield 3828a and a second shield. The shell 3706 may provide or otherwise define a first clocking receptacle 3830a (FIG. 7B) and a second clocking receptacle 3830b (FIG. 7B), and the mount 3708 may provide or otherwise define a first clocking post 3832a (FIG. 7A) and a second clocking post 3832b (FIG. 7A). The shell 3706 is properly aligned with the mount 3708 by mating the first and second clocking receptacles 3830a, 3830b with the first clocking posts 3832a, 3832b, respectively.

[0066] 7A , the inner surface of the mount 3708 can provide or otherwise define a number of pockets or recesses configured to receive various component parts of the sensor control device 3702 when the shell 3706 is mated to the mount 3708. For example, the inner surface of the mount 3708 can define a battery locator 3834 configured to receive a portion of the battery 3812 when the sensor control device 3702 is assembled. An adjacent contact pocket 3836 can be configured to receive a portion of the axial contact 3814a.

[0067] Additionally, a plurality of module pockets 3838 may be defined within the interior surface of the mount 3708 for receiving various electronic modules 3806 positioned on the bottom surface of the PCB 3804. Additionally, a shield locator 3840 may be defined within the interior surface of the mount 3708 for receiving at least a portion of the second shield 3828b when the sensor control device 3702 is assembled. The battery locator 3834, the contact pocket 3836, the module pocket 3838, and the shield locator 3840 all extend a short distance into the interior surface of the mount 3708, such that the overall height H of the sensor control device 3702 may be reduced as compared to conventional sensor control devices. The module pockets 3838 may assist in minimizing the diameter of the PCB 3804 by allowing PCB components to be positioned on both sides (i.e., top and bottom).

[0068] Continuing to refer to FIG. 7A, the mount 3708 can further include a plurality of carrier gripping features 3842 (two shown) defined interspersed about its circumference. The carrier gripping features 3842 are axially offset from a bottom surface 3844 of the mount 3708, where a transfer adhesive (not shown) can be applied during assembly. In contrast to conventional sensor control devices that typically include a conical carrier gripping feature that intersects with the bottom surface of the mount, the carrier gripping features 3842 of the present disclosure are offset from this plane (i.e., bottom surface 3844), where a transfer adhesive is applied. This can prove advantageous in helping to ensure that the delivery system is not inadvertently attached to the transfer adhesive during assembly. Additionally, the carrier gripping features 3842 of the present disclosure eliminate the need for a scalloped transfer adhesive, thereby facilitating the manufacture of the transfer adhesive and eliminating the need to precisely clock the transfer adhesive to the mount 3708. This, in turn, increases the bonding area and therefore the bond strength.

[0069] 7B, the bottom surface 3844 of the mount 3708 may provide or otherwise define a plurality of grooves 3846 that may be defined at or near the periphery of the mount 3708 and spaced equidistant from one another. A transfer adhesive (not shown) may be bonded to the bottom surface 3844, and the grooves 3846 may be configured to assist in transporting moisture from the sensor control device 3702 to around the mount 3708 during use. In some embodiments, the spacing of the grooves 3846 may be sandwiched between module pockets 3838 (FIG. 7A) defined on the opposite (inner) side of the mount 3708. As will be appreciated, alternating the location of the grooves 3846 and the module pockets 3838 ensures that opposing features do not extend into one another on both sides of the mount 3708. This may help maximize utilization of material for the mount 3708, thereby assisting in maintaining a minimum height H of the sensor control device 3702. The module pocket 3838 can significantly reduce mold collapse and improve the flatness of the bottom surface 3844 to which the transfer adhesive adheres.

[0070] 7B , the inner surface of the shell 3706 can also provide or otherwise define a number of pockets or recesses configured to receive various component parts of the sensor control device 3702 when the shell 3706 is mated to the mount 3708. For example, the inner surface of the shell 3706 can define an opposing battery locator 3848 positionable opposite the battery locator 3834 ( FIG. 7A ) of the mount 3708 and configured to receive a portion of the battery 3812 when the sensor control device 3702 is assembled. The opposing battery locator 3848 extends a short distance into the inner surface of the shell 3706, which helps reduce the overall height H of the sensor control device 3702.

[0071] An inner surface of the shell 3706 may provide or otherwise define thereon a tip and sensor locator 3852. The tip and sensor locator 3852 may be configured to receive both a tip (not shown) and a portion of the sensor 3716. The tip and sensor locator 3852 may be configured to align and / or mate with a corresponding tip and sensor locator 2054 ( FIG. 7A ) provided on the inner surface of the mount 3708.

[0072] An alternative sensor assembly / electronics assembly connection technique is illustrated in Figures 8A-8C in accordance with an embodiment of the present disclosure. As shown, the sensor assembly 14702 includes a sensor 14704, a connector support 14706, and a prong 14708. Among other things, a recess or receptacle 14710 can be defined in a bottom surface of a mount for the electronics assembly 14712, which can provide a location for receiving the sensor assembly 14702 to be coupled to the electronics assembly 14712, thereby fully assembling the sensor control device. The contours of the sensor assembly 14702 can be shaped in a manner that matches or is complementary to the receptacle 14710, which includes a resilient sealing member 14714 (including a conductive material that is coupled to a circuit board and aligns with the electrical contacts of the sensor 14704). 8C is formed when snapped or otherwise attached to the electronics assembly 14712 by forcing the sensor assembly 14702 into a recess 14710 integrally formed in the electronics assembly 14712. This embodiment provides an integral connector for the sensor assembly 14702 in the electronics assembly 14712.

[0073] Additional information regarding sensor assemblies is provided in U.S. Patent Publication No. 2013 / 0150691 and U.S. Patent Publication No. 2021 / 0204841, the entire contents of each of which are incorporated by reference into this specification.

[0074] According to the disclosed embodiments of the present invention, the sensor control device 102 can be modified to provide a one-piece architecture that can provide sterilization techniques specifically designed for the one-piece architecture sensor control device. The one-piece architecture allows the sensor applicator 150 and the sensor control device 102 to be shipped to the user in a single sealed package that does not require any final user assembly steps. In other words, the user only needs to unpack one package and then deliver the sensor control device 102 to the target monitoring location. The one-piece system architecture described herein can prove advantageous by eliminating component parts, various fabrication process steps, and user assembly steps. This results in less packaging and waste, and less user error or contamination of the system.

[0075] Figures 9A and 9B are side and cross-sectional side views, respectively, of an exemplary embodiment of the sensor applicator 102 coupled with the applicator cap 210. More specifically, Figure 9A illustrates how the sensor applicator 102 may be shipped to and received by a user, and Figure 9B depicts the sensor control device 4402 positioned within the sensor applicator 102. By these figures, the fully assembled sensor control device 4402 is already installed within the assembled sensor applicator 102 prior to delivery to the user, thus eliminating any additional steps that the user may otherwise have to perform.

[0076] The fully assembled sensor control device 4402 can be loaded into the sensor applicator 102, and then the applicator cap 210 can be coupled to the sensor applicator 102. In some embodiments, the applicator cap 210 can be threaded onto the housing 208 and can include an unsealing ring 4702. When the applicator cap 210 is rotated (e.g., twisted off) relative to the housing 208, the unsealing ring 4702 can be unsealed, thereby releasing the applicator cap 210 from the sensor applicator 102.

[0077] In accordance with the present disclosure, the sensor control device 4402, while loaded into the sensor applicator 102, can be provided with a gas chemical sterilization 4704 configured to sterilize its electronics housing 4404 and any other exposed parts. To effect this sterilization, a chemical can be injected into a sterilization chamber 4706 cooperatively defined by the sensor applicator 102 and the interfaced cap 210. In some applications, the chemical can be injected into the sterilization chamber 4706 through one or more vents 4708 defined in the applicator cap 210 at its proximal end 610. Exemplary chemicals that can be used for the gas chemical sterilization 4704 include, but are not limited to, ethylene oxide, hydrogen peroxide vapor, nitrogen oxides (such as, for example, nitrous oxide, nitrogen dioxide), and steam.

[0078] The sensor 4410 and distal portion of the tip 4412 are sealed within the sensor cap 4416 so that the chemicals used during the gas chemical sterilization process do not interact with the enzymes, chemical agents, or biological agents provided on the tail 4524 and other sensor components, such as the thin film coating that conditions the analyte inflow.

[0079] Once a desired level of sterility has been reached within the sterilization chamber 4706, the gas solution can be removed and the sterilization chamber 4706 can be aerated. Aeration can be accomplished by a series of vacuums followed by circulating a gas (e.g., nitrogen) or sterile air through the gas sterilization chamber 4706. Once the sterilization chamber 4706 is properly aerated, the vent 4708 can be blocked with a seal 4712 (shown in dashed lines).

[0080] In some embodiments, the seal 4712 may include two or more layers composed of different materials. The first layer may be made of a synthetic material (e.g., flash-spun high density polyethylene fiber) such as Tyvek® available from DuPont®. Tyvek® is highly durable, puncture resistant, and allows vapor transmission. The Tyvek® layer may be applied prior to the gas-chemical sterilization process, and following the gas-chemical sterilization process, a foil or other steam- and moisture-resistant material layer may be sealed (e.g., heat-fused) over the Tyvek® layer to prevent ingress of contaminants and moisture into the sterilization chamber 4706. In other embodiments, the seal 4712 may include only a single protective layer applied to the applicator cap 210. In such embodiments, this single layer may be gas-permeable for the sterilization process, but may also function as a protection against moisture and other harmful elements after the sterilization process is completed.

[0081] With the seal 4712 in place, the applicator cap 210 provides a barrier to external contamination, thereby maintaining a sterile environment for the assembled sensor control device 4402 until the user removes (unscrews) the applicator cap 210. The applicator cap 210 can create a dust-free environment that prevents the adhesive patch 4714 from becoming contaminated during shipping and storage.

[0082] 10A and 10B are isometric and side views, respectively, of another exemplary sensor control device 5002 in accordance with one or more embodiments of the present disclosure. The sensor control device 5002 may be similar in some respects to the sensor control device 102 of FIG 1 and therefore may be most clearly understood with reference thereto. Moreover, the sensor control device 5002 may replace the sensor control device 102 of FIG 1 and therefore may be used in conjunction with the sensor applicator 102 of FIG 1, which may deliver the sensor control device 5002 to a target monitor location on the skin of a user.

[0083] However, unlike the sensor control device 102 of FIG. 1, the sensor control device 5002 may include a one-piece system architecture that does not require a user to unpack multiple packages and final assemble the sensor control device 5002 prior to addition. In other words, upon receipt by the user, the sensor control device 5002 is already fully assembled and properly positioned within the sensor applicator 150 (FIG. 1). To use the sensor control device 5002, the user need only open one barrier (e.g., applicator cap 708 of FIG. 3B) for use, and then immediately dispatch the sensor control device 5002 to a target monitoring location.

[0084] As shown, the sensor control device 5002 includes an electronics housing 5004 that is generally disc-shaped and can have a circular cross-section. However, in other embodiments, the electronics housing 5004 can exhibit other cross-sectional shapes, such as oval or polygonal, without departing from the scope of the present disclosure. The electronics housing 5004 can be configured to house or otherwise contain various electrical components used to operate the sensor control device 5002. In at least one embodiment, an adhesive patch (not shown) can be positioned on a bottom surface of the electronics housing 5004. The adhesive patch can be similar to the adhesive patch 105 of FIG. 1 and can thus assist in adhering the sensor control device 5002 to a user's skin for use.

[0085] As shown, the sensor control device 5002 includes an electronics housing 5004 that includes a shell 5006 and a mateable mount 5008. The shell 5006 may be secured to the mount 5008 by a variety of methods, such as a snap engagement, an interference fit, sonic welding, one or more mechanical fasteners (e.g., screws), a gasket, an adhesive, or any combination thereof. In some cases, the shell 5006 may be secured to the mount 5008 such that a sealed interface is generated between the shell 5006 and the mount 5008.

[0086] The sensor control device 5002 may further include a sensor 5010 (partially visible) and a tip 5012 (partially visible) that is used to assist in transcutaneously delivering the sensor 5010 beneath the skin of a user during application of the sensor control device 5002. As shown, corresponding portions of the sensor 5010 and tip 5012 extend distally from a bottom surface of the electronics housing 5004 (e.g., mount 5008). The tip 5012 may include a tip hub 5014 configured to securely support the tip 5012. As seen most clearly in FIG. 10B, the tip hub 5014 may include or otherwise define a mating member 5016. To couple the tip 5012 to the sensor control device 5002, the tip 5012 can be advanced axially through the electronics housing 5004 until the tip hub 5014 engages the top surface of the shell 5006 and the mating member 5016 extends distally from the bottom surface of the mount 5008. Once the tip 5012 penetrates the electronics housing 5004, the exposed portion of the sensor 5010 can be received within the hollow or recessed (arcuate) portion of the tip 5012. The remainder of the sensor 5010 is positioned within the electronics housing 5004.

[0087] The sensor control device 5002 may further include a sensor cap 5018, which is shown in FIGS. 10A-10B disassembled or separated from the electronics housing 5004. The sensor cap 5016 may be removably coupled to the sensor control device 5002 (e.g., electronics housing 5004) at or near the bottom of the mount 5008. The sensor cap 5018 may assist in providing a sealing barrier surrounding the exposed portions of the sensor 5010 and the point 5012 to protect against gas chemical sterilization. As shown, the sensor cap 5018 may include a generally cylindrical body having a first end 5020a and an opposing second end 5020b. The first end 5020a may be open to provide access into an interior chamber 5022 defined within the body. In contrast, the second end 5020b may be closed and may provide or otherwise define an engagement feature 5024. As described herein, the engagement feature 5024 can assist in mating the sensor cap 5018 with a cap (e.g., applicator cap 708 of FIG. 3B) of a sensor applicator (e.g., sensor applicator 150 of FIGS. 1 and 3A-3G) and can assist in removing the sensor cap 5018 from the sensor control device 5002 when the cap is removed from the sensor applicator.

[0088] The sensor cap 5018 can be removably coupled to the electronics housing 5004 at or near a bottom surface of the mount 5008. More specifically, the sensor cap 5018 can be removably coupled to a mating member 5016 that extends distally from a bottom surface of the mount 5008. In at least one embodiment, for example, the mating member 5016 can define a set of male threads 5026a (FIG. 10B) that can mate with a set of female threads 5026b (FIG. 10A) defined by the sensor cap 5018. In some embodiments, the male and female threads 5026a, 5026b can include a square thread design (e.g., lacking a helical curvature), which can prove advantageous for molding these parts. Alternatively, the male and female threads 5026a, 5026b can include a helical threaded engagement. Thus, the sensor cap 5018 can be threadably coupled to the sensor control device 5002 at the mating member 5016 of the sharp body hub 5014. In other embodiments, the sensor cap 5018 can be removably coupled to the mating member 5016 by other types of engagement including, but not limited to, an interference or friction fit, or a frangible member or material that can be broken with a small separation force (e.g., axial or rotational force).

[0089] In some embodiments, the sensor cap 5018 may include a unitary (single) structure extending between the first end 5020a and the second end 5020b. However, in other embodiments, the sensor cap 5018 may include two or more component parts. In the illustrated embodiment, for example, the sensor cap 5018 may include a seal ring 5028 positioned at the first end 5020a and a desiccant cap 5030 positioned at the second end 5020b. The seal ring 5028 may assist in sealing the inner chamber 5022 as described in more detail below. In at least one embodiment, the seal ring 5028 may include an elastomeric O-ring. The desiccant cap 5030 may store or include a desiccant that assists in maintaining a preferred humidity level within the inner chamber 5022. Additionally, the desiccant cap 5030 may define or otherwise provide an engagement feature 5024 for the sensor cap 5018.

[0090] 11A-11C are step-by-step cross-sectional side views illustrating the assembly of a sensor applicator 102 and a sensor control device 5002 according to one or more embodiments. Once the sensor control device 5002 is fully assembled, it can be loaded into the sensor applicator 102. With reference to FIG. 11A, the sharps hub 5014 can include or otherwise define hub snap tabs 5302 configured to assist in coupling the sensor control device 5002 to the sensor applicator 102. More specifically, the sensor control device 5002 can be advanced into the sensor applicator 102 and the hub snap tabs 5302 can be received by corresponding arms 5304 of a sharps carrier 5306 positioned within the sensor applicator 102.

[0091] 11B shows the sensor control device 5002 received by the sharp body carrier 5306 and thus secured within the sensor applicator 102. Once the sensor control device 5002 is loaded into the sensor applicator 102, the applicator cap 210 can be coupled to the sensor applicator 102. In some embodiments, the applicator cap 210 and housing 208 can have a set of counter-mateable threads 5308 that allow the applicator cap 210 to be twisted onto the housing 208 in a clockwise (or counter-clockwise) direction, thereby securing the applicator cap 210 to the sensor applicator 102.

[0092] As shown, the sheath 212 is further positioned within the sensor applicator 102, and the sensor applicator 102 can include a sheath locking mechanism 5310 configured to ensure that the sheath 212 does not prematurely collapse during an impact event. In the illustrated embodiment, the sheath locking mechanism 5310 can include a threaded engagement between the applicator cap 210 and the sheath 212. More specifically, one or more female threads 5312a can be defined or otherwise provided on an inner surface of the applicator cap 210, and one or more male threads 5312b can be defined or otherwise provided on the sheath 212. The female threads 5312a and male threads 5312b can be configured to threadably mate when the applicator cap 210 is threadedly engaged with the sensor applicator 102 at the threads 5308. The female and male threads 5312 a , 5312 b can have the same thread pitch as the threads 5308 , which allow the applicator cap 210 to be screwed onto the housing 208 .

[0093] 11C shows the applicator cap 210 fully threadedly coupled to the housing 208. As shown, the applicator cap 210 may further include or otherwise define a cap post 5314 centrally positioned therein and extending proximally from a bottom surface of the applicator cap 210. The cap post 5314 may be configured to receive at least a portion of the sensor cap 5018 when the applicator cap 210 is twisted onto the housing 208.

[0094] With the sensor control device 5002 loaded into the sensor applicator 102 and the applicator cap 210 properly secured, the sensor control device 5002 can then be subjected to a gas chemical sterilization configured to sterilize the electronics housing 5004 and any other exposed portions of the sensor control device 5002. Because the sensor 5010 and the distal portion of the tip 5012 are sealed in the sensor cap 5018, the chemicals used during the gas chemical sterilization process cannot interact with the enzymes, chemical agents, and biological agents provided on the tail 5104 and on other sensor components, such as the thin film coating that conditions the analyte inflow.

[0095] 12A-12C are step-by-step cross-sectional side views illustrating assembly and disassembly of an alternative embodiment of a sensor applicator 102 and a sensor control device 5002 according to one or more additional embodiments. As generally described above, the fully assembled sensor control device 5002 can be loaded into the sensor applicator 150 by coupling the hub snap prongs 5302 into the arms 5304 of a sharps carrier 5306 positioned in the sensor applicator 150.

[0096] In the illustrated embodiment, the sheath arm 5604 of the sheath 212 can be configured to interact with a first detent 5702a and a second detent 5702b defined within the housing 208. The first detent 5702a may alternatively be referred to as a "locking" detent and the second detent 5702b may alternatively be referred to as a "firing" detent. When the sensor control device 5002 is initially installed within the sensor applicator 150, the sheath arm 5604 may be received within the first detent 5702a. As described below, the sheath 212 may be actuated to move the sheath arm 5604 to the second detent 5702b, thereby placing the sensor applicator 150 in a firing position.

[0097] 12B, applicator cap 210 is aligned with and advanced for housing 208 such that sheath 212 is received within applicator cap 210. Instead of rotating applicator cap 210 relative to housing 208 to couple applicator cap 210 to housing 208, threads of applicator cap 210 can be snap-locked onto corresponding threads of housing 208. Axial cuts or slots 5703 (one shown) defined in applicator cap 210 can allow a portion of applicator cap 210 proximate its threads to bend outwardly and snap-lock into engagement with threads of housing 208. When applicator cap 210 is snap-locked onto housing 208, sensor cap 5018 can be snap-locked into cap post 5314 accordingly.

[0098] 11A-11C , the sensor applicator 102 can include a sheath locking mechanism configured to ensure that the sheath 212 does not prematurely collapse during an impact event. In the illustrated embodiment, the sheath locking mechanism includes one or more ribs 5704 (one shown) defined near a base of the sheath 212 and configured to interact with one or more ribs 5706 (two shown) and a shoulder 5708 defined near a base of the applicator cap 210. The rib 5704 can be configured to engage between the rib 5706 and the shoulder 5708 during attachment of the applicator cap 210 to the housing 208. More specifically, once applicator cap 210 is snapped onto housing 208, applicator cap 210 can be rotated (e.g., clockwise) which positions rib 5704 of sheath 212 between rib 5706 and shoulder 5708 of applicator cap 210, which "locks" applicator cap 210 in place until a user counter-rotates applicator cap 210 to remove it for use. Engagement of rib 5704 between rib 5706 and shoulder 5708 of applicator cap 210 can prevent sheath 212 from prematurely collapsing.

[0099] In Figure 12C, the applicator cap 210 has been removed from the housing 208. As with the embodiment of Figures 11A-11C, the applicator cap 210 can be removed by counter-rotating it, which correspondingly rotates the cap post 5314 in the same direction and unscrews the sensor cap 5018 from the fitting 5016, generally as described above. Additionally, disconnecting the sensor cap 5018 from the sensor control device 5002 exposes the sensor 5010 and a distal portion of the tip 5012.

[0100] When the applicator cap 210 is unscrewed from the housing 208, a rib 5704 defined on the sheath 212 can slidingly engage an upper surface of a rib 5706 defined on the applicator cap 210. The upper surface of the rib 5706 can provide a corresponding raised surface that effects an upward displacement of the sheath 212 when the applicator cap 210 is rotated, moving the sheath 212 upward and bending the sheath arm 5604 out of engagement with the first detent 5702a and into receipt in the second detent 5702b. When the sheath 212 moves to the second detent 5702b, the radial shoulder 5614 disengages from radial engagement with the carrier arm 5608, thereby allowing the passive spring force of the spring 5612 to push the tip carrier 5306 upward, forcing the carrier arm 5608 out of engagement with the groove 5610. As the sharps carrier 5306 moves upward within the housing 208, the engaging member 5016 may be correspondingly retracted until it is flush, substantially flush, or near-flush with the bottom surface of the sensor control device 5002. At this point, the sensor applicator 102 is in the fired position. Thus, in this embodiment, removing the applicator cap 210 correspondingly retracts the engaging member 5016.

[0101] 13A-13F illustrate exemplary details of an embodiment of an internal device configuration for "firing" the applicator 216 to apply the sensor control device 222 to a user, including safely retracting the tines 1030 back into the used applicator 216. These figures, taken together, depict an exemplary sequence of driving the tines 1030 (carrying a sensor coupled to the sensor control device 222) into the user's skin, withdrawing the tines while leaving the sensor in operable contact with the user's interstitial fluid, and adhesively adhering the sensor control device to the user's skin. With reference to these figures, one skilled in the art will be able to discern modifications of such operations for use with alternative applicator assembly embodiments and components. Additionally, the applicator 216 can be a sensor applicator having a one-piece or two-piece architecture as disclosed herein.

[0102] 13A, the sensor 1102 is supported within the tip 1030 slightly above the user's skin 1104. A rail 1106 (optionally three rails 1106) on the upper guide section 1108 can be provided to control the movement of the applicator 216 relative to the sheath 318. The sheath 318 is secured within the applicator 216 by a detent feature 1110 such that an appropriate downward force along the longitudinal axis of the applicator 216 will overcome the resistance provided by the detent feature 1110 such that the tip 1030 and the sensor control device 222 can be translated along the longitudinal axis into (and onto) the user's skin 1104. Additionally, the catch arm 1112 of the sensor carrier 1022 engages the tip retraction assembly 1024 to maintain the tip 1030 in position relative to the sensor control device 222.

[0103] 13B, a user force is applied to overcome and disable the detent feature 1110, causing the sheath 318 to collapse into the housing 314 and drive the sensor control device 222 (along with the attached portions) to translate downward along the longitudinal axis as shown by arrow L. The inner diameter of the upper guide section 1108 of the sheath 318 constrains the position of the carrier arm 1112 throughout the entire stroke of the sensor / sharp insertion process. The retention of the stop surface 1114 of the carrier arm 1112 against the complementary surface 1116 of the sharp retraction assembly 1024 maintains the position of these members with the return spring 1118 at its maximum bias. According to an embodiment, instead of using a user force to drive the sensor control device 222 to translate downward along the longitudinal axis as shown by arrow L, the housing 314 can include a button (by way of example and not limitation, a push button) that activates a drive spring (by way of example and not limitation, a coil spring) to drive the sensor control device 222.

[0104] In Figure 13C, the sensor 1102 and tip 1030 have reached maximum insertion depth. In doing so, the carrier arm 1112 passes through the inner diameter of the upper guide section 1108. The compression force of the coil return spring 1118 then drives the angled stop surface 1114 radially outward, releasing a force that drives the tip carrier 1102 of the tip retraction assembly 1024 to pull the (slotted or otherwise configured) tip 1030 out of the user and away from the sensor 1102, as shown by arrow R in Figure 13D.

[0105] With the sharps 1030 fully retracted, as shown in Figure 13E, the final locking mechanism 1120 is engaged into the upper guide section 1108 of the sheath 318. As shown in Figure 13F, the used applicator assembly 216 is removed from the insertion site, leaving the sensor control device 222 behind, with the sharps 1030 safely secured inside the applicator assembly 216. At this point, the used applicator assembly 216 is ready to be discarded.

[0106] The actuation of the applicator 216 when applying the sensor control device 222 is designed to give the user the feeling that both the insertion and retraction of the point 1030 are performed automatically by the internal features of the applicator 216. In other words, the present invention avoids the user from feeling that he or she is forcing the point 1030 into his or her skin. Thus, after the user applies enough force to overcome the resistance from the detent features of the applicator 216, the resulting action of the applicator 216 is perceived as an automatic response to the applicator being "triggered". Even though all the driving force to insert the point 1030 is provided by the user and no additional biasing / driving means are used, the user does not perceive that he or she is providing additional force to drive the point 1030 to penetrate the skin. As detailed above in FIG. 13C, the retraction of the point 1030 is automated by the coil return spring 1118 of the applicator 216.

[0107] With respect to any of the applicator embodiments described herein, and any of the components of the applicator embodiments, including but not limited to the tip, tip module, and sensor module embodiments, those skilled in the art will appreciate that these embodiments can be dimensioned and configured to be suitable for use with a sensor configured to sense a level of an analyte in a bodily fluid within the epidermis, dermis, or subcutaneous tissue of a subject. In some embodiments, for example, the tip and distal portion of the analyte sensor disclosed herein can be dimensioned and configured to be positioned at a particular distal depth (i.e., the deepest penetration point into a tissue or layer of the subject's body, e.g., the epidermis, dermis, or subcutaneous tissue). With respect to some applicator embodiments, those skilled in the art will appreciate that certain embodiments of the tip can be dimensioned and configured to be positioned at a different distal depth within the subject's body as compared to the final distal depth of the analyte sensor. In some embodiments, for example, the tip can be positioned at a first distal depth within the epidermis of the subject prior to retraction, whereas the distal portion of the analyte sensor can be positioned at a second distal depth within the dermis of the subject. In other embodiments, the tip may be positioned at a first distal depth within the dermis of the subject prior to retraction, while a distal portion of the analyte sensor may be positioned at a second distal depth within subcutaneous tissue of the subject. In yet other embodiments, the tip may be positioned at a first distal depth and the analyte sensor may be positioned at a second distal depth prior to retraction, both of which are within the same layer or tissue of the subject's body.

[0108] In addition, one of ordinary skill in the art will appreciate that for any of the applicators described herein, the analyte sensor and one or more structured components coupled to the analyte sensor, including but not limited to the one or more spring mechanisms, may be positioned within the applicator at an off-center location relative to one or more axes thereof. In some applicator embodiments, for example, the analyte sensor and spring mechanism may be positioned at a first off-center location on a first side of the applicator relative to the applicator axis, and the sensor electronics may be positioned at a second off-center location on a second side of the applicator relative to the applicator axis. In other applicator embodiments, the analyte sensor, spring mechanism, and sensor electronics may be positioned at off-center locations on the same side of the applicator axis. One of ordinary skill in the art will appreciate that other permutations and configurations in which any or all of the analyte sensor, spring mechanism, sensor electronics, and other components of the applicator are positioned in a central or off-center location relative to one or more axes of the applicator are possible and fully within the scope of the present disclosure.

[0109] Additional details of suitable devices, systems, methods, components, and their operation, along with associated functionality, are described in International Patent Publication No. WO2018 / 136898 to Rao et al., International Patent Publication No. WO2019 / 236850 to Thomas et al., International Patent Publication No. WO2019 / 236859 to Thomas et al., International Patent Publication No. WO2019 / 236876 to Thomas et al., and U.S. Patent Publication No. 2020 / 0196919, filed June 6, 2019, the entire contents of each of which are incorporated herein by reference. Additional details regarding the applicator, embodiments of its components, and variations thereof are described in U.S. Patent Publication Nos. 2013 / 0150691, 2016 / 0331283, and 2018 / 0235520, the entire contents of all of which are incorporated herein by reference for all purposes. Additional details regarding the tip module, tips, embodiments of its components, and variations thereof are described in U.S. Patent Publication No. 2014 / 0171771, the entire contents of which are incorporated herein by reference for all purposes.

[0110] A biochemical sensor can be described by one or more sensing properties. A common sensing property is called the sensitivity of a biochemical sensor, which is a measure of the sensor's responsiveness to the concentration or composition of the chemical that the biochemical sensor is designed to detect. In electrochemical sensors, this response may be in the form of current (amperometric) or charge (coulometric). In other types of sensors, the response may be in a different form, such as photon intensity (e.g., light). The sensitivity of a biochemical analyte sensor can vary depending on several factors, including whether the sensor is in an in vitro or in vivo condition.

[0111] FIG. 14 is a graph depicting the in vitro sensitivity of an amperometric analyte sensor. The in vitro sensitivity can be accessed by testing the sensor in vitro at various analyte concentrations and then performing a regression (e.g., linear or non-linear) or other curve fit on the resulting data. In this example, the sensitivity of the analyte sensor is linear or substantially linear and can be modeled according to the equation y=mx+b, where y is the output current of the sensor, x is the level (or concentration) of the analyte, m is the slope of the sensitivity, and b is the intercept of the sensitivity that corresponds approximately to the background signal (e.g., noise). For sensors with a linear or substantially linear response, the level of analyte corresponding to a given current can be determined from the slope and intercept of the sensitivity. Sensors with non-linear sensitivity require additional information to determine the level of analyte resulting from the output current of the sensor, and one of ordinary skill in the art would be familiar with schemes for modeling non-linear sensitivity. In certain embodiments of an in vivo sensor, the in vitro sensitivity may be the same as the in vivo sensitivity, while in other embodiments, a transfer (or transformation) function is used to convert the in vitro sensitivity to an in vivo sensitivity applicable to the intended in vivo use of the sensor.

[0112] Calibration is a technique for improving or maintaining accuracy by adjusting the measured output of a sensor to reduce the difference from the expected output of the sensor. One or more parameters describing the sensing characteristics of the sensor, such as sensitivity, are established for use in making the calibration adjustments.

[0113] Certain in vivo analyte monitor systems require calibration to be performed after implantation of the sensor in a user or patient, either by user intervention or automatically by the system itself. For example, when user intervention is required, the user performs an in vitro measurement (e.g., a blood glucose (BG) measurement using a finger prick and an in vitro test strip) while the analyte sensor is implanted and enters the measurement into the system. The system compares the in vitro measurement to the in vivo signal and uses the difference to determine an estimate of the in vivo sensitivity of the sensor. The in vivo sensitivity can then be used for an algorithmic process to convert data collected with the sensor into a value indicative of the user's analyte level. This process and other processes that require user action to perform a calibration are referred to as "user calibration." Systems may require user calibration due to instability in the sensitivity of the sensor, such that the sensitivity drifts or changes over time. Thus, multiple user calibrations (e.g., on a periodic (e.g., daily) schedule, on a variable schedule, or as needed) may be required to maintain accuracy. The embodiments described herein may incorporate some degree of user calibration as appropriate for a particular implementation, but in general user calibration is not preferred as it requires the user to perform painful or otherwise difficult BG measurements and can introduce user error.

[0114] Some in vivo analyte monitor systems can periodically adjust calibration parameters through the use of automated measurements of sensor characteristics performed by the system itself (e.g., processing circuitry executing the software). Repeated adjustment of the sensor's sensitivity based on variables measured by the system (rather than the user) is generally referred to as "system" (or automatic) calibration, and can be performed with or without user calibration, such as the BG measurements discussed above. As with repeated user calibration, repeated system calibration is generally necessitated by drift in the sensor's sensitivity over time. Thus, although the embodiments described herein can be used with some degree of automated system calibration, preferably the sensor's sensitivity is relatively stable over time such that post-execution calibration is not required.

[0115] Some in vivo analyte monitor systems operate with factory calibrated sensors. Factory calibration refers to the determination or estimation of one or more calibration parameters prior to delivery to a user or healthcare professional (HCP). The calibration parameters may be determined by the sensor manufacturer (or by the manufacturer of other components of the sensor control device, if the latter manufacturer is different from the sensor manufacturer). Many in vivo sensor manufacturing processes process sensors in groups or batches called production lots, production-stage lots, or simply lots. A single lot may contain several thousand sensors.

[0116] The sensor may include a calibration code or parameters that may be derived or determined during one or more sensor manufacturing processes and encoded or programmed into a data processing device of the analyte monitoring system as part of the manufacturing process, or may be provided on the sensor itself, for example as a bar code, laser tag, RFID tag, or other machine-readable information displayed on the sensor. When the code is provided to a receiver (or other data processing device), user calibration during in vivo use of the sensor may be avoided or the frequency of in vivo calibration while the sensor is worn may be reduced. In embodiments in which the calibration code or parameters are provided on the sensor itself, the calibration code or parameters may be automatically transmitted or provided to a data processing device in the analyte monitoring system prior to or at the start of sensor use.

[0117] Some in-vivo analyte monitor systems operate with sensors that can be one or more of factory calibrated, system calibrated, and / or user calibrated. For example, a sensor can be provided with a calibration code or calibration parameters that can enable factory calibration. If this information is provided to the receiver (e.g., entered by a user), the sensor can operate as a factory calibrated sensor. If this information is not provided to the receiver, the sensor can operate as a user calibrated sensor and / or a system calibrated sensor.

[0118] In yet another aspect, programming or executable instructions may be provided or stored within the data processing device and / or receiver / controller unit of the analyte monitoring system for providing a time-varying adjustment algorithm to the in-vivo sensor during use. For example, a predetermined or analytical curve or database may be generated based on retrospective statistical analysis of the analyte sensor used in vivo and corresponding glucose level feedback that is time-based and configured to apply additional adjustments to one or more in-vivo sensor parameters to compensate for potential sensor drift or other factors in the stability profile.

[0119] In accordance with the presently disclosed subject matter, the analyte monitor system can be configured to compensate or adjust the sensor sensitivity based on the sensor drift profile. A time-varying parameter β(t) can be defined or determined based on an analysis of the sensor behavior during in vivo use, and a time-varying drift profile can be determined. In certain aspects, the compensation or adjustment of the sensor sensitivity can be programmed into a receiver unit, controller, or data processor of the analyte monitor system such that the compensation or adjustment, or both, can be performed automatically and / or iteratively as sensor data is received from the analyte sensor. In accordance with the presently disclosed subject matter, the adjustment or compensation algorithm can be user initiated or executed (rather than self-initiated or self-executing) such that the adjustment or compensation of the analyte sensor sensitivity profile is performed or executed upon user initiation or invocation of a corresponding function or routine or when the user enters a sensor calibration code.

[0120] According to the subject matter of the present disclosure, each sensor in a sensor lot (not including the sample sensor used for in vivo testing in some cases) can be non-destructively inspected to determine or measure sensor characteristics such as film thickness at one or more points on the sensor, and other characteristics can be measured or determined, including physical characteristics such as the area / volume of the active area. Such measurements or determinations can be performed using an automated method, for example, using an optical scanner or other suitable measurement device or system, and the sensor characteristics determined for each sensor in the sensor lot are compared to corresponding average values ​​based on the sample sensors for possible correction of the calibration parameters or calibration codes assigned to each sensor. For example, with the calibration parameters defined as sensor sensitivity, the sensitivity is approximately inversely proportional to the film thickness, so that for example, for a sensor having a measured film thickness that is about 4% greater than the average film thickness for sensors sampled from the same sensor lot, in one embodiment the sensitivity assigned to the sensor is the average sensitivity determined from the sample sensors divided by 1.04. Similarly, sensitivity is approximately proportional to the active area of ​​the sensor, so that for a sensor with a measured active area that is about 3% smaller than the average active area for sensors sampled from the same sensor lot, the assigned sensitivity for that sensor is the average sensitivity multiplied by 0.97. The assigned sensitivity can be determined by multiple successive adjustments for each test or measurement of that sensor from the average sensitivity from the sample sensors. In certain embodiments, the testing or measurement of each sensor can further include measuring the film thickness and / or the area or volume of the active sensing area as well as the viscosity or texture of the film.

[0121] Additional information regarding sensor calibration is provided in U.S. Patent Publication Nos. 2010 / 00230285 and 2019 / 0274598, the entire contents of each of which are incorporated by reference herein.

[0122] The storage memory 5030 of the sensor 110 may include software blocks related to the communication protocol of the communication module. For example, the storage memory 5030 may include a BLE service software block having functions to provide an interface to make the BLE module 5041 available to the computer hardware of the sensor 110. These software functions may include a BLE logic interface and an interface parser. The BLE services provided by the communication module 5040 may include a generic access profile service, a generic attribute service, a generic access service, a device information service, a data transmission service, and a security service. The data transmission service may be a primary service used to transmit data such as sensor control data, sensor status data, analyte measurement data (past and present), and event log data. The sensor status data may include error data, currently active, and software state. The analyte measurement data may include information such as current and past raw measurements, current and past values ​​after processing with appropriate algorithms or models, predictions and trends of measurement levels, comparison of other values ​​to patient-specific averages, invocation of actions determined by algorithms or models, and other similar types of data.

[0123] According to aspects of the presently disclosed subject matter, as embodied herein, the sensor 110 can be configured to communicate with multiple devices simultaneously by adapting the capabilities of the communication protocol or medium supported by its hardware and radio. As an example, the BLE module 5041 of the communication module 5040 can be provided with software or firmware to enable multiple simultaneous connections between the sensor 110 as a central device and multiple other devices as peripheral devices, or multiple simultaneous connections of the sensor 110 as a peripheral device when another device is the central device.

[0124] A connection between two devices using a communication protocol such as BLE, and the resulting communication session, can be characterized by a similar physical channel operating between the two devices (e.g., the sensor 110 and the data receiving device 120). The physical channel can include a single channel or a set of channels, including, by way of example and not limitation, using an agreed-upon set of channels determined by a common clock and a channel hopping or frequency hopping sequence. A communication session can use a similar amount of the available communication spectrum and can exist in the vicinity of multiple such communication sessions. In certain embodiments, each set of devices in a communication session uses a different physical channel or set of physical channels to manage interference with devices in the same vicinity.

[0125] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a procedure for sensor-receiver connection for use with the subject matter of the present disclosure. First, the sensor 110 repeatedly advertises its connection information to its environment in search of the data receiving device 120. The sensor 110 may repeat the advertisement periodically until a connection is established. The data receiving device 120 detects the advertisement packet and scans and filters for the sensor 120 to connect with the data provided therein. The data receiving device 120 then sends a scan request command, and the sensor 110 responds with a scan response packet providing additional details. The data receiving device 120 then sends a connection request with the associated Bluetooth device address. The data receiving device 120 may continue to request to establish a connection to the sensor 110 with the specific Bluetooth device address. The devices then establish an initial connection that allows them to start exchanging data with each other. The devices begin the process to initialize the data exchange service and perform a mutual authentication procedure.

[0126] During the first connection between the sensor 110 and the data receiving device 120, the data receiving device 120 can initialize a discovery procedure of services, characteristics, and attributes. The data receiving device 120 can evaluate these capabilities of the sensor 110 and store them for use during subsequent connections. The sensor 110 and the data receiving device 120 then enable notification of the respective corresponding security services to be used for mutual authentication of these devices. The mutual authentication procedure can be automated and may not require user involvement. Following successful completion of the mutual authentication procedure, the sensor 110 sends a connection parameter update to request the data receiving device 120 to use connection parameter settings configured for itself, preferably to maximize longevity.

[0127] The data receiving device 120 then implements a sensor control procedure to backfill the historical data, current data, event log, and factory data. As an example, the data receiving device 120 sends a request to start the backfill process for each type of data. The request can specify a defined recording range based on, for example, measurements or timestamps, as appropriate. The sensor 110 responds with the request data until all previously unsent data in its memory is sent to the data receiving device 120. The sensor 110 can respond to the backfill request from the data receiving device 120 that it has already sent all data. Once backfilling is complete, the data receiving device 120 can notify the sensor 110 that it is ready to receive periodic measurement readings. The sensor 110 can repeatedly send the readings over multiple notifications. As embodied herein, the multiple notifications can be redundant notifications to ensure that the data is sent correctly. Alternatively, the multiple notifications can constitute a single payload.

[0128] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a procedure for sending a shutdown command to the sensor 110. The shutdown operation is performed when the sensor 110 is, for example, in an error state, a misinsertion state, or a sensor expired state. If the sensor 110 is not in these states, the sensor 110 can record the command and perform the shutdown when the sensor 110 transitions to the error state or the sensor expired state. The data receiving device 120 sends a properly formatted shutdown command to the sensor 110. If the sensor 110 is in an active state and processing another command, it will respond with a standard error response indicating that the sensor 110 is busy. Otherwise, the sensor 110 will send a response when it receives the command. Additionally, the sensor 110 will send a success notification by the sensor control, which is characterized by sending an acknowledgment that the command was received. The sensor 110 will register the shutdown command. At the next appropriate opportunity (e.g., depending on the current sensor state as described herein), the sensor 110 will shut down.

[0129] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a high-level depiction of a state machine representation 6000 of actions that may be taken by the sensor 110, as shown in FIG. 15. After initialization, the sensor 110 enters a state 6005 related to its manufacture. In the manufacture state 6005, the sensor 110 may be configured for operation, e.g., writing to the storage memory 5030 may be performed. At various times while in state 6005, the sensor 110 checks for a received command to move to the save state 6015. Upon entering the save state 6015, the sensor performs a software integrity check. While in the save state 6015, the sensor may receive a wake-up request command, after which it proceeds to the insertion detection state 6025.

[0130] Upon entering state 6025, the sensor 110 may store information about devices authorized to communicate with the sensor as configured during startup or may initialize algorithms related to processing and interpreting measurements from the sensing hardware 5060. The sensor 110 may start a life cycle timer responsible for maintaining its active operation time count and may begin communicating with authorized devices to transmit recorded data. While in the insertion detection state 6025, the sensor 110 may enter state 6030, where it checks whether the operation time is equal to a predefined threshold. This operation time threshold may correspond to a timeout function to determine whether the insertion is successful. If the operation time reaches the threshold, the sensor 110 proceeds to state 6035, where it checks whether the average data read amount is greater than a threshold amount corresponding to the expected data read amount to trigger the detection of a successful insertion. If the data read amount is lower than the threshold while in state 6035, the sensor proceeds to state 6040, corresponding to a failed insertion. If the amount of data read meets the threshold, the sensor proceeds to the active pairing state 6055.

[0131] The active pairing state 6055 of the sensor 110 reflects a state in which the sensor 110 is operating normally by recording measurements, processing measurements, and reporting these measurements as necessary. While in the active pairing state 6055, the sensor 110 attempts to send measurements or establish a connection with the receiving device 120. The sensor 110 further increments the operating time. The sensor 110 transitions to the active lapsed state 6065 once it reaches a predetermined threshold operating time (e.g., the operating time reaches a predetermined threshold). The active lapsed state 6065 of the sensor 110 reflects a state in which the sensor 110 has operated for its maximum predetermined amount of time.

[0132] While in the active revoked state 6065, the sensor 110 may generally perform operations related to gradually winding down operation and, if necessary, ensuring that collected measurements have been securely transmitted to the receiving device. For example, while in the active revoked state 6065, the sensor 110 may transmit collected data and, if a connection is unavailable, may intensify attempts to find and establish a connection with nearby authenticated devices. While in the active revoked state 6065, the sensor 110 may receive a shutdown command in state 6070. If a shutdown command is not received, the sensor 110 may check whether the operation time has exceeded a final operation threshold in state 6075. The final operation threshold may be based on the battery life of the sensor 110. The normal transmission state 6080 corresponds to a final operation of the sensor 110, and ultimately shuts down the sensor 110.

[0133] Before the sensor is powered up, the ASIC 5000 is in a low power storage mode state. The power up process can begin, for example, when an incident RF field (e.g., an NFC field) drives the voltage of the power supply to the ASIC 5000 to a value greater than a reset threshold, causing the sensor 110 to enter a wake-up state. While in the wake-up state, the ASIC 5000 enters a power-up sequence state. The ASIC 5000 then wakes up the communication module 5040. The communication module 5040 is initialized and a power-on self-test is triggered. The power-on self-test can include the ASIC 5000 communicating with the communication module 5040 using a specified sequence of reading and writing data to verify that the memory and one-time programmable memory are not corrupted.

[0134] When the ASIC 5000 first enters the measurement mode, an insertion detection sequence is performed to verify that the sensor 110 is properly attached on the patient's body before a proper measurement can be taken. Initially, the sensor 110 interprets a command to initiate a measurement configuration process to place the ASIC 5000 in a measurement command mode. The sensor 110 then briefly enters a measurement lifecycle state in which it performs several consecutive measurements to test whether the insertion was successful. The communication module 5040 or the ASIC 5000 evaluates the measurement results to determine whether the insertion was successful. If the insertion is deemed successful, the sensor 110 enters a measurement state where it begins to take periodic measurements using the sensing hardware 5060. If the sensor 110 determines that the insertion was not successful, it is triggered to enter an insertion failure mode, where the ASIC 5000 is commanded to return to storage mode, while the communication module 5040 disables itself.

[0135] 1A further illustrates an exemplary operating environment for providing over-the-air ("OTA") updates for use with the techniques described herein. An operator of the analyte monitoring system 100 can package updates to the data receiving device 120 or sensor 110 into updates to applications running on the general-purpose data receiving device 130. Using the communication channels available between the data receiving device 120, the general-purpose data receiving device 130, and the sensor 110, the general-purpose data receiving device 130 can receive periodic updates to the data receiving device 120 or sensor 110 and initiate the installation of these updates on the data receiving device 120 or sensor 110. The general-purpose data receiving device 130 acts as an installation or update platform for the data receiving device 120 or sensor 110, since applications that enable the general-purpose data receiving device 130 to communicate with the analyte sensor 110, the data receiving device 120, and / or a remote application server 150 can update software or firmware on the data receiving device 120 or sensor 110 without wide area networking capabilities.

[0136] As embodied herein, a remote application server 150 operated by the manufacturer of the analyte sensor 110 and / or the operator of the analyte monitoring system 100 can provide software and firmware updates to the devices of the analyte monitoring system 100. In certain embodiments, the remote application server 150 can provide the latest software and firmware to the user device 140 or directly to the general-purpose data receiving device. As embodied herein, the remote application server 150 can provide application software updates to the application storefront server 160 using an interface provided by the application storefront. The general-purpose data receiving device 130 can periodically communicate with the application storefront server 160 to download and install updates.

[0137] After the multipurpose data receiving device 130 downloads an application update including a firmware or software update for the data receiving device 120 or the sensor 110, the data receiving device 120 or the sensor 110 and the multipurpose data receiving device 130 establish a connection. The multipurpose data receiving device 130 determines that a firmware or software update is available for the data receiving device 120 or the sensor 110. The multipurpose data receiving device 130 can provide the software or firmware update for transmission to the data receiving device 120 or the sensor 110. As an example, the multipurpose data receiving device 130 can compress or split data related to the software or firmware update, or can encrypt or decrypt the firmware or software update, or can perform an integrity check on the firmware or software update. The multipurpose data receiving device 130 sends data related to the firmware or software update to the data receiving device 120 or the sensor 110. Additionally, the multipurpose data receiving device 130 can send commands to initiate an update to the data receiving device 120 or the sensor 110. Additionally or alternatively, the multipurpose data receiving device 130 can include commands to facilitate the update, such as commands to provide notifications to its user and to keep the data receiving device 120 and the multipurpose data receiving device 130 connected to and close to a power source until the update is complete.

[0138] The data receiving device 120 or the sensor 110 receives data for the update and a command to start the update from the multipurpose data receiving device 130. The data receiving device 120 can then install the firmware or software update. To install the update, the data receiving device 120 or the sensor 110 can put itself into or resume in a so-called "safe" mode, which has only limited operating capabilities. Once the update is complete, the data receiving device 120 or the sensor 110 re-enters or resets in a standard operating mode. The data receiving device 120 or the sensor 110 can perform one or more self-diagnostic tests to determine that the firmware or software update has been successfully installed. The multipurpose data receiving device 130 can receive a notification of a successful update. The multipurpose data receiving device 130 can then report confirmation of the successful update to the remote application server 155.

[0139] In a particular embodiment, the storage memory 5030 of the sensor 110 includes a one-time programmable (OTP) memory. The term OTP memory can refer to a memory that includes access restrictions and security to facilitate a predetermined number of writes to a particular address or segment in the memory. The memory 5030 can be pre-organized into a number of pre-allocated memory blocks or memory bins. The bins are pre-allocated to a fixed size. When the storage memory 5030 is a one-time programmable memory, the bins can be considered to be in a non-programmable state. Additional bins that have not yet been written to can be in a programmable or writable state. Containerizing the storage memory 5030 in this manner can improve portability of the code and data to be written to the storage memory 5030. Updating the software of a device (e.g., a sensor device as described herein) stored in an OTP memory can be performed by replacing only the code in one or more particular bins that were previously written with the latest code written to one or more new bins, rather than replacing all the code in the memory. In a second embodiment, the memory is not pre-organized. Instead, the space allocated to the data is dynamically allocated or determined as needed. Piecewise updates can be issued since containers of various sizes may be defined in which updates are expected.

[0140] 16 illustrates an exemplary operational and data flow diagram for over-the-air (OTA) programming of the storage memory 5030 in the sensor device 100 in accordance with the subject matter of the present disclosure, as well as the use of the memory during execution of a process by the sensor device 110 after OTA programming. In the exemplary OTA programming 500 illustrated in FIG. 5, a request to initiate OTA programming (or reprogramming) is sent from an external device (e.g., data receiving device 130). At 511, the communication module 5040 of the sensor device 110 receives an OTA programming command. The communication module 5040 sends the OTA programming command to the microcontroller 5010 of the sensor device 110.

[0141] After receiving the OTA programming command, the microcontroller 5010 may verify the validity of the OTA programming command at 531. For example, the microcontroller 5010 may determine whether the OTA programming command is signed with a proper digital signature token. Upon determining that the OTA programming command is valid, the microcontroller 5010 may set the sensor device to an OTA programming mode. At 532, the microcontroller 5010 may verify the validity of the OTA programming data. At 533, the microcontroller 5010 may reset the sensor device 110 to reinitialize the sensor device 110 in the programming state. Once the sensor device 110 transitions to the OTA programming state, the microcontroller 5010 may begin writing data to the rewritable memory 540 (e.g., memory 5020) of the sensor device at 534 and may further write data to the OTP memory 550 (e.g., storage memory 5030) of the sensor device at 535. The data written by the microcontroller 5010 may be based on the verified OTA programming data. The microcontroller 5010 may write data marking one or more programming blocks or programming areas of the OTP memory 550 as incorrect or inaccessible. The data written to the free or unused portions of the OTP memory may be used to replace the incorrect or inaccessible programming blocks of the OTP memory 550. After the microcontroller 5010 has written the data to the respective memories at 534 and 535, it may perform one or more software integrity checks to ensure that no errors were introduced into the programming blocks during the writing process. After it has been determined that the data was written without error, the microcontroller 5010 may resume normal operation of the sensor device.

[0142] In the execution mode, the microcontroller 5010 can retrieve a programming manifest or programming profile from the rewritable memory 540 at 536. The programming manifest or programming profile can include a list of legitimate software programming blocks and can further include program execution guides for the sensor 110. By following the programming manifest or programming profile, the microcontroller 5010 can determine which memory blocks of the OTP memory 550 are appropriate to execute and can avoid executing or referencing expired data of programming blocks that are deemed expired or fraudulent. At 537, the microcontroller 5010 can selectively retrieve memory blocks from the OTP memory 550. At 538, the microcontroller 5010 can use the retrieved memory blocks by executing programming code stored in the memory or using variables stored therein.

[0143] As embodied herein, a first security layer for communications between the analyte sensor 110 and other devices may be established based on security protocols dictated by and embedded in the communications protocol used for communication. Another security layer may be based on communications protocols that require proximity of the communicating devices. Additionally, certain packets and / or certain data encapsulated therein may be encrypted, while other packets and / or other data within the packets may or may not be otherwise encrypted. Additionally or alternatively, application layer encryption may be used in conjunction with one or more block or stream ciphers to establish mutual authentication and communications encryption with other devices in the analyte monitoring system 100.

[0144] The ASIC 5000 of the analyte sensor 110 may be configured to dynamically generate authentication and encryption keys using data held in the storage memory 5030. The storage memory 5030 may be pre-programmed with a set of valid authentication and encryption keys for use with a particular class of device. The ASIC 5000 may be further configured to perform an authentication procedure with the other device using the received data and apply the generated key to the sensitive data before transmitting the sensitive data. The generated key may be unique to the analyte sensor 110, unique to a pair of devices, unique to a communication session between the analyte sensor 110 and the other device, unique to a message sent during the communication session, or unique to a block of data of the message that is enclosed therein.

[0145] Both the sensor 110 and the data receiving device 120 can vouch for the authority of the other party in the communication session, for example, to issue commands or receive data. In certain embodiments, identity authentication can be performed by two functions. First, the party asserting identity provides a valid proof signed by the device manufacturer or the operator of the analyte monitoring system 100. Second, authentication can be performed using public and private keys established by the analyte monitoring system 100 device or by the operator of the analyte monitoring system 100, and a shared secret derived therefrom. To verify the identity of the other party, the party can provide proof that it has control of the private key.

[0146] The manufacturers of the analyte sensors 110, data receiving devices 120, or providers of applications for the general-purpose data receiving device 130 may provide the information and programming necessary for these devices to communicate securely through secure programming and updates. For example, the manufacturer may provide information that can be used to generate encryption keys (e.g., entropy-based random values) for each device, including a secure root key for the analyte sensors 110 and optionally the data receiving devices 120 that can be used in combination with device specific information and operational data to generate unique encryption values ​​for the device, session, or data transmission as needed.

[0147] Analyte data associated with a user is sensitive data due at least in part to the fact that it can be used for a variety of purposes, including health monitoring and drug dosage determination purposes. In addition to user data, the analyte monitor system 100 can implement security hardening against attempts by outsiders to reverse engineer it. The communication connection can be encrypted using device-specific or session-specific encryption keys. Encrypted or unencrypted communications between any two devices can be verified using transmission integrity checks built into the communication. The analyte sensor 110 operation can be protected from tampering by restricting access to read and write functionality to the memory 5020 through the communication interface. The sensor can be configured to only allow access to known or "trusted" devices that are listed in a "white list" or devices that can provide a pre-determined code associated with the manufacturer or other authorized users. The white list may represent a limited scope, meaning that no connection identifiers other than those included therein should be used, or a preferred scope where the white list is searched first, but other devices may still be used. Additionally, the sensor 110 can reject or block a connection request if the requestor fails to complete a login procedure over the communication interface within a predetermined time period (e.g., within 4 seconds). These properties provide protection against certain denial of service attacks, particularly against BLE interfaces.

[0148] As embodied herein, the analyte monitoring system 100 may employ periodic key rotation to further reduce key disablement and tampering. The key rotation strategy employed by the analyte monitoring system 100 may be designed to accommodate backward compatibility of devices deployed or distributed at a site. As an example, the analyte monitoring system 100 may employ keys designed to be compatible with multiple generations of keys used by upstream devices for downstream devices (e.g., at a site or unable to provide updates in a feasible manner).

[0149] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a message sequence diagram 600 for use with the subject matter of the present disclosure shown in FIG. 17 and specifying an exemplary data interaction between a pair of devices, specifically a sensor 110 and a data receiving device 120. The data receiving device 120 may be a data receiving device 120 or a general-purpose data receiving device 130 as embodied herein. In step 605, the data receiving device 120 may send a sensor wake-up command 605 to the sensor 110, for example through a short-range communication protocol. The sensor 110 may be primarily dormant prior to step 605 and may conserve battery power until a full wake-up is required. During step 610 after wake-up, the sensor 110 may collect data or perform other operations appropriate to the sensing hardware 5060 of the sensor 110. In step 615, the data receiving device 120 may initiate an authentication request command 615. In response to the authentication request command 615, both the sensor 110 and the data receiving device 120 can engage in a mutual authentication process 620. The mutual authentication process 620 can include the transfer of data including challenge parameters that enable the sensor 110 and the data receiving device 120 to ensure that the other device is fully capable of adhering to the agreed upon security framework described herein. Mutual authentication can be based on the ability of two or more entities to authenticate each other, verifying the establishment of a secret key by a challenge response with or without the involvement of an online trusted third party. Mutual authentication can be implemented using two, three, four, or five-pass authentication, or similar versions thereof.

[0150] Following a successful mutual authentication process 620, in step 625, the sensor 110 can provide the data receiving device 120 with a sensor secret 625. The sensor secret includes a sensor-specific value and can be derived from a random value generated during manufacturing. The sensor secret can be encrypted before or during transmission to prevent third parties from accessing it. The sensor secret 625 can be encrypted by one or more of the keys generated by the mutual authentication process 620 or accordingly. In step 630, the data receiving device 120 can derive a sensor-specific encryption key from the sensor secret. The sensor-specific encryption key can further be session-specific. Thus, the sensor-specific encryption key can be determined by each device without being transmitted between the sensor 110 and the data receiving device 120. In step 635, the sensor 110 can encrypt the data to be included in the payload. In step 640, the sensor 110 can transmit the encrypted payload 640 to the data receiving device 120 using the communication link established between its appropriate communication model and the appropriate communication model of the data receiving device 120. In step 645, the data receiving device 120 can decrypt the payload using the sensor-specific encryption key derived during step 630. Following step 645, the sensor 110 can send out additional data (including newly collected) and the data receiving device 120 can process the received data appropriately.

[0151] As discussed herein, the sensor 110 may be a device that has only limited processing capabilities, battery power, and storage capacity. The encryption techniques (e.g., selection of cryptographic algorithms or implementations thereof) used by the sensor 110 may be selected based at least in part on these limitations. The data receiving device 120 may be a more powerful device that has fewer limitations of this nature. Thus, the data receiving device 120 may use more sophisticated and computationally intensive encryption techniques, such as cryptographic algorithms and implementations.

[0152] The analyte sensor 110 can be configured to modify discoverability behavior to attempt to increase the probability that a receiving device will receive a proper data packet and / or reduce other limitations that may result in a lack of ability to provide or receive an acknowledgement signal. Modifying the discoverability behavior of the analyte sensor 110 can include, by way of example and not limitation, modifying how often connection data is included in data packets, modifying how often data packets are generally transmitted, lengthening or shortening the broadcast window for data packets, modifying the amount of time the analyte sensor 110 waits to receive an acknowledgement or scanning signal after a broadcast, including a directional communication (e.g., via one or more trial transmissions) to one or more devices that may have previously communicated with the analyte sensor 110 and / or one or more devices on a whitelist, modifying the transmit power for the communications module when broadcasting a data packet (e.g., to increase the distance of the broadcast or to reduce energy consumption to increase the battery life of the analyte sensor), modifying the rate at which data packets are prepared and broadcast, or a combination of one or more other modifications. Additionally or alternatively, the receiving device may also adjust parameters related to the device's listening behavior to increase the likelihood of receiving data packets containing connection data.

[0153] As embodied herein, the analyte sensor 110 may be configured to broadcast data packets using two types of windows. The first window refers to the rate at which the analyte sensor 110 is configured to activate its communications hardware. The second window refers to the rate at which the analyte sensor 110 is configured to be in an active transmission (e.g., broadcast) state of data packets. As an example, the first window may indicate that the analyte sensor 110 activates its communications hardware to transmit and / or receive data packets (including connection data) during the first two seconds of each 60 second period. The second window may indicate that the analyte sensor 110 transmits a data packet every 60 milliseconds during each two second window. The remainder of the two second window, the analyte sensor 110 is scanning. The analyte sensor 110 may extend or shorten either window to modify its discoverability behavior.

[0154] In certain embodiments, the discoverability behavior of the analyte sensor may be stored in a discoverability profile and modifications may be made based on one or more factors such as the status of the analyte sensor 110 and / or by applying rules based on the status of the analyte sensor 110. For example, these rules may reduce the power consumed by the broadcast process to the analyte sensor 110 when the battery level of the analyte sensor 110 falls below a predetermined amount. As another example, configuration settings for broadcasting or otherwise transmitting packets may be adjusted based on the ambient temperature, the temperature of the analyte sensor 110, or the temperature of certain components of the communication hardware of the analyte sensor 110. In addition to modifying the transmission power, other parameters related to the transmission function or transmission process of the communication hardware of the analyte sensor 110 may be modified, including but not limited to the rate, frequency, and timing of transmission. As another example, when the analyte data indicates that the subject is experiencing or about to experience an adverse health event, the rules described above may increase the discoverability of the analyte sensor 110 to alert receiving devices of the adverse health event.

[0155] As embodied herein, certain calibration functions for the sensing hardware 5060 of the analyte sensor 110 may be adjusted based on a function of the external or internal environment, and also to compensate for natural degradation of the sensing hardware 5060 during extended periods of non-use (e.g., a "shelf life" prior to use). The calibration functions of the sensing hardware 5060 may be adjusted automatically by the sensor 110 (e.g., by operation of the ASIC 5000 which modifies functions in the memory 5020 or storage 5030) or may be adjusted by other devices in the analyte monitoring system 100.

[0156] As an example, the sensor sensitivity of the sensing hardware 5060 can be adjusted based on external temperature data or time since manufacture. If the external temperature is monitored during storage of the sensor, the presently disclosed subject matter can adaptively change the compensation of the sensor sensitivity over time as the device experiences changes in storage conditions. By way of example and not limitation, adaptive sensitivity adjustment can be implemented using an "active" storage mode in which the analyte sensor 110 is periodically woken up to measure temperature. These features can conserve the battery of the analyte device and extend the life of the analyte sensor. At each temperature measurement, the analyte sensor 110 can calculate a sensitivity adjustment amount over that period based on the measured temperature. The temperature weighted adjustment amount can then be accumulated over the active storage mode period to calculate a total sensor sensitivity adjustment value at the end of the active storage mode (e.g., upon insertion). Similarly, upon insertion, the sensor 110 can determine the time difference between the time of manufacture of itself or the sensing hardware 5060 (which can be written to the ASIC 5000's storage 5030) and modify the sensor sensitivity or other calibration functions according to one or more known natural degradation rates or natural degradation formulas.

[0157] Additionally, for purposes of illustration and not limitation, as embodied herein, the sensor sensitivity adjustment can take into account other sensor conditions, such as sensor drift. For example, in the event of sensor drift, the sensor sensitivity adjustment amount can be hard coded into the sensor 110 during manufacturing based on an estimate of how much an average sensor is expected to drift. The sensor 110 can use a calibration function having a time-varying function for the sensor's offset and gain that can account for drift over its wear period. Thus, the sensor 110 can use a function that accounts for the sensor's 110 drift over time and represents the sensor sensitivity, and is used to convert interstitial current to interstitial glucose using a device-dependent function that can be device specific, in combination with a glucose profile baseline. Such a function that takes into account sensor sensitivity and drift can improve the accuracy of the sensor 110 over wear periods without requiring user calibration.

[0158] The sensor 110 detects raw measurements from the sensing hardware 5060. On-sensor processing can be performed, such as by one or more models trained to interpret the raw measurements. The models can be machine learning models trained off-device to detect, predict, or interpret the raw measurements to detect, predict, or interpret the levels of one or more analytes. Additional trained models can be run based on the output of the machine learning models trained to interact with the raw measurements. As an example, these models can be used to detect, predict, or recommend events based on the raw measurements and the type of analytes detected by the sensing hardware 5060. Events can include the initiation or completion of a physical activity, a meal, the application of a medical procedure or drug, an emergency health event, and other events of a similar nature.

[0159] The model may be provided to the sensor 110, data receiving device 120, or general-purpose data receiving device 130 during manufacturing or during firmware or software updates. The model may be periodically refined, such as by the manufacturer of the sensor 110 or the operator of the analyte monitor system 100, based on data received from the sensor 110 and data receiving devices of an individual user or multiple users collectively. In certain embodiments, the sensor 110 includes sufficient computational components to support further training or refinement of the machine learning model based on the unique features of the user to which it is attached, and the like. The machine learning model may include, by way of example and not limitation, models trained using or including decision tree analysis, gradient boosting, adaptive boosting, artificial neural networks or variations thereof, linear discriminant analysis, nearest neighbor analysis, support vector machines, supervised or unsupervised classification, and others. The model may include algorithmic models or rule-based models in addition to machine learning models. Model-based processing may be performed by other devices, including the data receiving device 120 or general-purpose data receiving device 130, upon receiving data from the sensor 110 (or other downstream devices).

[0160] Data transmitted between the sensor 110 and the data receiving device 120 may include raw or processed measurements. Data transmitted between the sensor 110 and the data receiving device 120 may further include alarms or notifications for display to a user. The data receiving device 120 may display or otherwise communicate notifications to a user based on the raw or processed measurements, or may display alarms when received from the sensor 110. Alarms that may be triggered for display to a user include alarms based on direct analyte values ​​(e.g., a momentary reading that exceeds or fails to meet a threshold), trends in analyte values ​​(e.g., average readings that exceed or fail to meet a threshold over a set period of time, slope), predictions of analyte values ​​(e.g., when an algorithmic calculation based on the analyte values ​​exceeds or fails to meet a threshold), sensor alerts (e.g., detection of a suspected malfunction), communication alerts (e.g., absence of communication between the sensor 110 and the data receiving device 120 for a threshold period of time, an unknown device attempting or failing to initiate a communication session with the sensor 110), reminders (e.g., reminders to charge the data receiving device 120, reminders to take medication or perform other activities), and other alerts of a similar nature. By way of example and not limitation, as embodied herein, the alarm parameters described herein may be configurable by the user, or may be fixed during manufacture or a combination of user-settable and non-user-settable parameters.

[0161] In accordance with the subject matter of the present disclosure, by way of example and not limitation, a device may include a multi-analyte sensor, a transimpedance amplifier, and a differential amplifier. The device may be embodied as an analyte sensing hardware. The multi-analyte sensor may include a first working electrode, a second working electrode, a counter electrode, and a reference electrode. Each of the first working electrode and the second working electrode may be configured to receive a signal indicative of the presence of a respective analyte. The analyte may include one or more of glucose, lactate, oxygen, A1C, alcohol, pH, beta-hydroxybutyrate, uric acid, creatinine, ketones, or other analytes as described herein. The counter electrode may be the sum of the first working electrode and the second working electrode. The transimpedance amplifier may be configured to receive a first signal from the first working electrode and a second signal from the second working electrode. The transimpedance amplifier may convert the received first and second signals to an output. The differential amplifier may be configured to subtract a bias offset from the output to generate a corrected output. The bias offset may be determined based on a first analyte measured by the first working electrode or a second analyte measured by the second working electrode. The differential amplifier may be further configured to calibrate out bias-dependent residuals and common-mode operational amplifier characteristics from the output to generate a corrected output. The bias-dependent residuals may be determined based on a two-point offset calibration for one of the first working electrode or the second working electrode. The common-mode operational amplifier characteristics may be determined based on a three-point calibration.

[0162] In accordance with the subject matter of the present disclosure, by way of example and not limitation, a device may include a multi-analyte sensor and an application specific integrated circuit (ASIC). The device may be embodied as an analyte sensing hardware. The multi-analyte sensor may include a first working electrode, a second working electrode, a counter electrode, and a reference electrode. Each of the first working electrode and the second working electrode may be configured to receive a signal indicative of the presence of a respective analyte. The analyte may include one or more of glucose, lactate, oxygen, A1C, alcohol, pH, beta-hydroxybutyrate, uric acid, creatinine, ketones, or other analytes as described herein. The ASIC may be configured to receive a first signal of the received signal from the first working electrode and a second signal of the received signal from the second working electrode. The ASIC may set a first independent bias voltage for the first working electrode and a second independent bias voltage for the second working electrode. The ASIC may generate data indicative of the analyte using the first independent bias voltage and the second independent bias voltage.

[0163] In accordance with the subject matter of the present disclosure, by way of example and not limitation, a device may include a multi-analyte sensor, a first application specific integrated circuit (ASIC), and a second ASIC. The device may be embodied as an analyte sensing hardware. The multi-analyte sensor may include a first working electrode, a second working electrode, a counter electrode, and a reference electrode. Each of the first working electrode and the second working electrode may be configured to receive a signal indicative of the presence of a respective analyte. The analyte may include one or more of glucose, lactate, oxygen, A1C, alcohol, pH, beta-hydroxybutyrate, uric acid, creatinine, ketones, or other analytes as described herein. The first ASIC may be configured to receive a first signal of the received signal from the first working electrode. The first ASIC may set a first independent bias voltage for the first working electrode. The first ASIC may generate data indicative of the first analyte using the first independent bias voltage. The second ASIC can be configured to receive a second of the received signals from the second working electrode. The second ASIC can set a second independent bias voltage for the second working electrode. The second ASIC can generate data indicative of the second analyte using the second independent bias voltage.

[0164] According to aspects of the present disclosure, the device may further include an analog-to-digital converter, a communication module, and a negative balanced bias amplifier. The analog-to-digital converter may be configured to convert the modified output to a digital output. Subtraction of the variable bias offset from the output may reduce the modified output to the range of the analog-to-digital converter. The communication module may be configured to process the digital output into a measurement result. The communication module may be separate from the device. The communication module may be further configured to provide the measurement result to a receiving device for display via wireless communication. The negative balanced bias amplifier may be configured to subtract a predetermined voltage from the reference electrode to generate a first working electrode bias for biasing the first working electrode. The predetermined voltage may be determined based on a first analyte measured by the first working electrode or a second analyte measured by the second working electrode. The negative balanced bias amplifier may be further configured to receive a reference signal from the reference electrode and a negative balanced reference value. Although the present disclosure describes the device as including a negative balanced bias amplifier, the present disclosure also contemplates the device as a positive balanced bias amplifier. The positive balanced bias amplifier can be configured to generate a first working electrode bias for biasing the first working electrode by adding a predetermined voltage to the reference electrode. The positive balanced bias amplifier can be further configured to receive a reference signal from the reference electrode and a positive balanced reference value. The device can be configured to detect blood ketone levels, blood glucose levels, or blood lactate levels, or other analyte levels.

[0165] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a sensor 110 for use with the subject matter of the present disclosure, as shown in FIG. 18. FIG. 18 illustrates a block diagram of an exemplary sensor 1810 according to an exemplary embodiment compatible with the embedded system architecture and communication scheme described herein. As embodied herein, the sensor 1810 may include a printed circuit board ("PCB") that acts as a backplate for the electronic components of the sensor. Coupled to the PCB is an application specific integrated circuit (ASIC) 1830 communicatively coupled to a communication module 1840, analyte sensing hardware 1855 selected to suit the monitoring function of the sensor 1810, and a thermistor 1857. The ASIC 1830 and communication module 1840 may be coupled to a battery 1850 that provides power to the ASIC 1830, the communication module 1840, and other components of the sensor 1810 not illustrated. As shown in FIG. 18, the ASIC 1830 and the communication module 1840 may be physically separate modules. Alternatively, the ASIC 1830 and the communications module 1840 may both be integrated into a single chip.

[0166] As embodied herein, the sensor 1810 can be designed to be power-saving, low-cost, and disposable, so the ASIC 1830 can include embedded non-volatile memory 1831. The ASIC can include a single reference clock used for applications such as communication and programming, memory management, and on-chip timers. The ASIC 1830 can receive power from a battery 1850 and regulated by a power manager 1837. Under conditions described herein, the components of the ASIC 1830 can receive power from an adjacent electric field by coupling with a communication chipset (e.g., an NFC radio front-end 1835) embedded within the ASIC 1830. The NFC radio front-end 1835 can comply with a corresponding power supply standard. As described herein, when the battery 1850 is connected, the NFC radio front-end 1835 can be activated. Alternatively, the NFC radio front-end 1835 can be used to activate the sensor 1810 and to energize the battery 1850. The ASIC 1830 may further include a serial-peripheral interface (SPI) 1833 and an analog front end (AFE) 1839 for communication with other components of the sensor 1810. For example, the SPI 1833 may be used to communicate with a communications module 1840 as described herein. The SPI 1833 may be used to test and program components of the sensor 1810 during manufacturing. Similarly, the AFE 1839 may be used to communicate with the analyte sensing hardware 1855. The sensor 1810 may include a communications module 1840 as described herein.

[0167] The non-volatile memory 1831 may be programmed by the manufacturer of the ASIC 1830, by the manufacturer of the sensor 1810 (if the two are manufactured by different entities or at different times), or during other configuration processes. The non-volatile memory 1831 of the ASIC 1830 may be programmed to include information such as an identifier for the ASIC 1830. The identifier may be used to uniquely identify the ASIC 1830 for identification and tracking purposes. The non-volatile memory 1831 of the ASIC 1830 may be programmed with configuration or calibration parameters suitable for use by the sensor 1810 and various components of the sensor 1810 including the NFC radio 1865, power manager 1837, analog front end 1839, analyte sensing hardware 1855, or for use by the communications module 1840.

[0168] The non-volatile memory can be further programmed to include a manufacturer code as part of or separate from the identifier for the ASIC 1830, the communication module 1840, or other components of the sensor 1810. As an example, each manufacturer of components that may be used in the sensor 1810 may be assigned an internationally recognized code designated by a standards setting organization such as, by way of example only, the International Organization for Standardization. The manufacturer code may be used to identify the manufacturer of the ASIC 1830. As embodied herein, the manufacturer code may be used to verify compatibility with the sensor 1810. For example, the sensor 1810 may be configured to be used only with receivers 1820 (or other devices) associated with or manufactured by a list of known manufacturers recognized by the manufacturer code, e.g., a "white list" of manufacturers. As another example, the sensor 1810 may be configured to deny operability with receivers 1820 associated with or manufactured by a list of excluded manufacturers, e.g., a "black list" of manufacturers. Similarly, the receiver 1820 may be configured to be compatible only with sensors 1810 associated with or manufactured by selected manufacturers.

[0169] In one embodiment, the determination of whether a device attempting to communicate or cooperate with the sensor 1810 will be recognized by the sensor 1810 can be made by the ASIC 1830. As described, a list of valid or invalid manufacturer codes can be programmed into the non-volatile memory 1831 of the ASIC 1830. The ASIC 1830 can then compare its list of manufacturer codes to the manufacturer code of the device attempting to communicate with the sensor 1810. Making this determination in the ASIC 1830 can be advantageous in that the non-volatile memory 1831 can be protected from modification after manufacturing of the ASIC 1830 and the sensor 1810 is completed. In another embodiment, the determination of whether communication with the device is enabled can be made by the communication module 1840. As an example, the communication module 1840 can be updated by the provider of the sensor 1810 to update the list of valid or invalid manufacturer codes (e.g., during a firmware update process). In this way, the list of valid or invalid manufacturer codes is not fixed at the time of manufacture but can be adjusted over time by the provider of the sensor 1810. For example, new manufacturers can be approved for interoperability or previously approved manufacturers can be blocked.

[0170] The update process, whether by firmware update or other process to update the data stored by the sensor 1810, and in particular the communication module, can be implemented through communication between the communication module 1810 and an update server provided by the provider of the sensor 1810 or its authorized agent. The communication module 1840 can connect to the update server by any of a variety of network protocols. For example, the communication module 1840 can include one or more long-range communication transceivers to enable it to communicate with the update server over a wide area network. By way of example only, the communication module 1840 can incorporate one or more wideband cellular network radios (and associated chipsets) to communicate using, for example, third generation standards (e.g., HSPA, HSPA+), fourth generation standards (e.g., Mobile WiMAX, LTE, LTE Advanced Pro), fifth generation standards (e.g., low frequency bands, mid frequency bands, high frequency bands). Additionally or alternatively, the communication module 1840 can include a Wi-Fi radio and chipset to communicate with a wide area network. Additionally or alternatively, the update process can be mediated by a second device, such as a mobile phone or personal computing device, which can securely receive updates from an update server and send them to the sensor 1810. In that regard, the sensor 1810 can connect to the update server using the communication capabilities of the second device.

[0171] By way of example only and not limitation, the exemplary communication module 1840 of the sensor 1810 may include a chipset compatible with various communication protocols including Bluetooth Low Energy ("BLE"), Near Field Communication ("NFC"), similar short-range communication schemes, wireless personal area network (WPAN) or piconet, wireless body area network (WBAN), ZigBee protocol, WIMAX protocol, or other IEEE 802.15 or IEEE 802.11 protocols, or infrared communication protocols according to the Infrared Data Association standard (IrDA), etc. The communication module 1840 may transmit and receive data and instructions by interacting with a similarly functional communication module 1860 of the receiver 1820. As described herein, the communication module 1840 may include a microcontroller 1843 for executing software operations defined in a memory that stores software blocks 1845. The software 1845 may be written into a suitable memory as a one-time programmable memory. The software 1845 can include software for an application layer 1846 and a link layer 1847. The application layer 1846 can include application software that is programmed into the communication module and controls the functionality of the sensor 1810 with respect to sensing actuation, measurement recording, measurement analysis, data processing, security applications, anti-tamper applications, error handling, and other individual corresponding functions. The link layer 1847 can include software that is programmed into the communication module 1840 and used to facilitate communication using a selected communication protocol. As an example, if the communication module includes a BLE chipset, the link layer 1847 can include software configured to manage communication using a BLE protocol. The link layer 1847 can be pre-configured or updated by the manufacturer of the communication module 1840, whereas the application layer 1846 can be configured or updated specifically by the manufacturer of the sensor 1810.

[0172] The communication module 1840 may further include a memory 1841 to support operation of the microcontroller 1843. The communication module 1840 may further include an interface (not illustrated) for communicating with other components of the sensor 1810. As embodied herein, the microcontroller 1843 of the communication module 1840 may have greater functionality compared to the ASIC 1830. As described herein, the microcontroller 1843 of the communication module 1840 may be a general purpose reprogrammable processor configured to take on more processing intensive tasks than the ASIC 1830.

[0173] As embodied herein, the sensor 1810 may be a disposable device having a predetermined life span and no wide area network communication capabilities. As embodied herein, the communication module 1840 may enable communication under battery power. The present disclosure is described with respect to an exemplary configuration of the sensor 1810, but other suitable configurations are contemplated. As an example, the processing hardware of the sensor 1810 may be embodied as another type of dedicated processor, such as a field programmable gate array (FPGA). As embodied herein, the processing hardware of the sensor 1810 (e.g., the communication module 1840) may include a general-purpose processing unit (e.g., a CPU) or another programmable processor that is temporarily configured by software to perform the functions of the sensor 1810. More generally, the processing hardware may be implemented using hardware, firmware, software, or a suitable combination thereof. By way of example and not limitation, the processing hardware of the sensor 1810 may be determined by one or more factors including computer capabilities, power capacity, memory capacity, networking availability, and the like.

[0174] As embodied herein, the processing duties of the ASIC 1830 and the communications module 1840 can be divided based on computational complexity and resources. The ASIC 1830 can be configured to focus on interpreting measurements and other data from the analyte sensing hardware 1855. For example, the ASIC 1830 can be configured to specifically interpret analog signals output by the analyte sensing hardware 1855 and received by the ASIC 1830 through the AFE 1839. Through interpretation, the ASIC 1830 can generate digital measurements for use with algorithms executed by the communications module 1840. The communications module 1840 can then perform advanced processing on the raw measurement signals received from the ASIC 1830. For example, the communications module 1840 can analyze the measurement signals to derive the analyte level and identify trends and actionable responses related to the patient, which are then transmitted to the receiver 1820. In certain embodiments, the ASIC 1830 can be configured to derive analyte levels for the patient, identify trends and actionable responses, and then provide the analysis results to the communications module 1840 for transmission to the receiver 1820.

[0175] To perform its sensing function, the sensor 1800 may further include appropriate analyte sensing hardware 1855 for this function. As embodied herein, the analyte sensing hardware 1855 may include, for example, an auto-injector prescribed to a patient for self-administration of a drug or other medication. Thus, the analyte sensing hardware 1855 may include a mechanism for driving a needle or plunger of a syringe to deliver the drug subcutaneously. The syringe may be pre-filled with the drug, and the syringe may be actuated in response to a trigger event. For example, the mechanism may drive a needle into the patient and advance a plunger to deliver the drug subcutaneously through the needle.

[0176] As embodied herein, the sensor 1810 may be configured as a body-worn syringe that is attachable to a patient's body tissue (such as, for example, skin, organ, muscle) and may be capable of automatically delivering a subcutaneous injection of a fixed or patient-selected dose of a drug over a controlled or selected period of time. In such an embodiment, the analyte sensing hardware 1855 or analyte sensor may include, for example, an adhesive or other means for temporarily attaching itself to the patient's body tissue, a primary container for storing the drug or pharmaceutical agent, a drive mechanism configured to drive a plunger to enable its release to expel the drug from the primary container, a trocar (e.g., a solid core needle), a flexible cannula positioned about the trocar, an insertion mechanism configured to insert the trocar and / or the flexible cannula into the patient and optionally retract the trocar while leaving the flexible cannula in the patient, a fluid path connector configured to establish fluid communication between the primary container and the flexible cannula upon activation of the device, and an actuator (e.g., a user-displaceable button) configured to activate the device. As embodied herein, the body worn syringe may be pre-filled and / or pre-loaded.

[0177] In addition to mechanical components, the analyte sensing hardware 1855 can include electrical and / or electronic components. For example, an electronic switch can be coupled to the mechanism described above. The sensor 1810 can establish authenticated communications, receive an encrypted signal, decrypt the signal using techniques of the present disclosure, determine that the signal includes instructions to activate a switch, and cause the switch to actuate a needle. As described above, the computing devices embodied herein can be configured to perform sensing functions using the analyte sensing hardware 1855 in response to remote commands.

[0178] As embodied herein, the analyte sensing hardware 1855 may include a travel sensor and an analog-to-digital converter (ADC) to generate a digital signal indicative of the distance the needle or plunger has traveled. When delivering the drug, the sensor 1810 may obtain a reading from the sensor and encrypt and securely report it to a peer device using techniques of the present disclosure. Additionally or alternatively, the sensor 1810 may report other measurements or parameters, such as, for example, the time the drug was delivered, the volume of drug delivered, any problems encountered while delivering the drug, etc. The sensor 1810 may be configured to provide data regarding the operation of the analyte sensing hardware 1855 to a remote device.

[0179] The analyte sensing hardware 1855 may be configured to perform any suitable combination of one or more sensing functions and may include one or more sensing components that may be configured to detect an operational state of the sensor 1810 (such as, for example, unpackaged / ready for administration, removal of a sterile barrier, contact with a patient's body tissue, insertion of a cannula and / or needle, initiation of drug delivery, displacement of an actuator or button, completion of drug delivery, plunger positioning, occlusion of a fluid path), a state of the sensor 1810 or a drug contained therein (such as, for example, temperature, exposure to shock or vibration, exposure to light, drug color, drug turbidity, drug viscosity, geographic location, spatial orientation, time information, ambient air pressure), and / or physiological information regarding the patient (such as, for example, body temperature, blood pressure, pulse or heart rate, glucose levels, physical activity or movement, fingerprint detection).

[0180] The analyte sensing hardware 1855 may be electrically connected to the PCB through multiple electrical connections, e.g., a working connection, a reference connection, and a counter connection. In embodiments where the analyte sensing hardware 1855 includes an analyte sensor incorporating multiple electrodes (and / or a multi-analyte sensor), each electrical connection may correspond to one or more of these electrodes. Voltages from these connections may be delivered to the ASIC 1830 (e.g., through the analog front end 1839). The analyte sensor may generate a current that flows between the electrodes and is dependent on the analyte concentration and temperature. The ambient conditions of the analyte sensor may also change over time, which may affect the voltage readings provided by the analyte sensing hardware to the ASIC 1830. The potential of one or more of the electrical connections (e.g., the counter connection) may be adjusted accordingly to ensure a relatively constant target voltage over the other electrical connections (e.g., the reference connection) for interpretation to determine the level of the analyte.

[0181] The thermistor 1857 may include one or more thermistors for measuring the temperature of the patient's skin to which the sensor 1810 is attached or other aspects of the operating environment of the sensor 1810, particularly the analyte sensing hardware 1855. As embodied herein, the measurement of the user's skin may be performed using a single element thermistor and trimmed resistive element within the ASIC 1830. The thermistor may be positioned such that its active element is positioned in close thermal contact with the patient's skin as close as possible to the sensor element (e.g., the analyte sensor sensing element). FIG. 21 shows a diagram of the thermistor measurement function 2100. To measure the thermistor temperature, the ASIC 1830 biases the thermistor element 2110 in series with the trimmed resistive element 2120 and resistive element 2130 therein. The ASIC 1830 measures the voltage across the resistive elements 2120 and 2130. The ASIC 1830 may average multiple measurements depending on the sampling frequency selected. The conversion to temperature can be an iterative calculation that first calculates the temperature based on the trimmed resistive element value and the Steinhart coefficient of the thermistor. A second calculation is then performed applying a temperature correction for the resistive element. Additionally, the calculation can include device specific parameters provided with the ASIC 1830.

[0182] FIG. 18 further illustrates a block diagram of an exemplary embodiment of a receiver 1820 for use with the subject matter of the present disclosure. As embodied herein, the receiver 1820 may include a small form factor device. The receiver 1820 may optionally be less memory or processing constrained than the sensor 1810, and may include sufficient memory for operating software storage and data storage, as embodied herein, and sufficient RAM for software execution to communicate with the sensor 1810 as described herein. The receiver 1820 may include a CPU 1860 communicatively coupled to a communication module 1870, a memory 1861, and a storage 1863. Power to the components of the receiver 1820 may be delivered by a power module 1867, which may include a rechargeable battery as embodied herein to enable sustained operation and continued use.

[0183] The receiver 1820 can be configured to wirelessly couple to or scan the sensor 1810 and, for example, retrieve sensing data or data related to the sensor from the sensor 1810. As embodied herein, the receiver 1820 can optionally include analyte sensing hardware 1865 similar to or extended from the analyte sensing hardware 1855 of the sensor 1810. By way of example only and not limitation, in an embodiment in which the analyte sensing hardware 1855 of the sensor 1810 is configured for a continuous glucose monitor, the analyte sensing hardware 1867 of the receiver 1820 can be configured with a blood glucose meter adapted for use with blood glucose test strips to extend the blood glucose monitor of the sensor 1810. In additional embodiments, the receiver 1820 does not include additional analyte sensing hardware 1865.

[0184] As embodied herein, the receiver 1820 can be configured to operate as an NFC scanner and a BLE endpoint through certain modules of the communication module 1870 with respect to the sensor 1810 described herein. As embodied herein, the receiver 1820 can be configured for communication through a Universal Serial Bus (USB) of the communication module 1870. As embodied herein, the on-board storage 1863 of the receiver 1820 can have the capability to store the sensed data received from the sensor 1810 over an extended period of time. Additionally, the receiver 1820 can be configured to communicate over a wide area network with a user computing device or a remote cloud server.

[0185] Upon successful activation of the sensor 1810 by the receiver 1820, the sensor 1810 can be configured to collect sensory data and make the data available to the receiver 1820. The receiver 1820 acts as a collector. As an example, the receiver can pair with the sensor 1810 through an NFC interface, provide short-range power to the sensor 1810, and be communicatively coupled to the sensor 1810 through the NFC interface. Alternatively, the receiver 1820 can be communicatively coupled to the sensor 1810 through a medium-range interface, such as a Bluetooth interface or a Bluetooth Low Energy ("BLE") interface, or any suitable interface compatible with the communication protocol implemented by the sensor 1810 as described herein. The sensor 1810 can transmit sensory data used for monitoring and alarm functions.

[0186] Bluetooth low energy, as used throughout this disclosure, refers to a medium-range communication protocol configured to make Bluetooth device pairing easy for end users. As described herein, the use of BLE on the sensor 1810 may optionally not rely on a standard BLE implementation of Bluetooth for security reasons, but may instead use application layer encryption using one or more block ciphers to establish mutual authentication and encryption. The use of a non-standard encryption design implemented at the application layer has several benefits. One benefit of this approach is that the pairing of the sensor 1810 and receiver 1820 can be completed using only an NFC scan by the user without the user needing to provide additional input, such as entering a security pin or confirming BLE pairing between the data receiving device and the sensor 1810. Another benefit is that this approach mitigates the possibility of allowing devices that are not in the immediate vicinity of the sensor 1810 to be inadvertently or intentionally paired, at least in part because the information used to support the pairing process is shared over a backup short-range communication link (e.g., NFC) over a short distance rather than a longer-range BLE channel. Furthermore, since no BLE pairing and bonding scheme is involved, pairing of the sensor 1810 can avoid chip vendor implementation issues or vulnerabilities in the BLE specification.

[0187] Since the data collected by the sensor 1810 and exchanged between the sensor 1810 and the data receiving device pertains to sensory information associated with a user, these data can be highly sensitive and advantageously protected. Sensor data relating to a patient can be considered sensitive data, at least in part due to the fact that the information can be used for a variety of purposes, including those related to health monitoring and drug dosage determination. As embodied herein, encryption and authentication can be used as two of the primary technical controls to provide protection. As embodied herein, the sensor 1810 and receiver 1820 can be configured to comply with security interfaces designed to protect confidentiality, integrity, and availability ("CIA"). Security features can be built into the hardware and software design to take CIA concerns into account.

[0188] To facilitate data confidentiality, the communication connection between the sensor 1810 and the receiver 1820 can be mutually authenticated by both devices prior to transmitting sensitive data. The communication connection can be encrypted using a device-specific or session-specific encryption key. To ensure data integrity, the encrypted communication between the sensor 1810 and the receiver 1820 can be verified using a transmission integrity check built into the communication to ensure that the patient data is unmodified. As embodied herein, after the two devices are each authenticated, session key information can be exchanged between these devices that can be used to encrypt the communication.

[0189] As embodied herein, each of the sensor 1810 and the receiver 1820 can employ various security measures to ensure confidentiality of data exchanged through a communication session and to facilitate associated devices to find and establish a connection with a trusted endpoint. As an example, the sensor 1810 can configure the communication module 1840 to use pre-configured advertising parameters with a public device address. The communication module can send connectable omni-directional advertising events and handle process scanning and connection requests from all receivers 1820. The sensor 1810 can request the communication module 1840 to start advertising immediately after the communication module 1840 is started. The communication module 1840 can continue advertising until it receives and accepts a connection request packet. Once connected to a receiver 1820, the communication module 1840 can be made undiscoverable thereafter. No other device can connect to the communication module 1840. The communication module 1840 can stop advertising if a connection request packet is not received within a predetermined amount of time (e.g., 2 seconds, 4 seconds). The sensor 1810 can stop advertising by configuring the communication module into a non-discoverable mode. Upon entering the non-discoverable mode, the communication module 1840 stops sending advertising events and no device can find or connect to the communication module 1840. To resume advertising, the sensor 1810 requests the communication module 1840 to advertise at every other instance when a measurement is recorded. Thus, when the sensor 1810 is connected to the receiver 1820, the communication module 1840 can resume advertising every two minutes. The sensor 1810 can continue the same advertising schedule using a timer when it is in a wake-up state with no measurement data being recorded.

[0190] These properties provide protection against certain denial of service attacks, particularly against BLE interfaces. As embodied herein, the identifier used to connect to a sensor 1810 can be variable to reduce the ability to track a single sensor 1810 as it connects to one or more data receiving devices. The connection identifier for the sensor 1810 or data receiving device can include, by way of example only, a unique or semi-unique device identifier, a medium access control address for the device's communication module, a device address configured for a particular communication protocol (such as, for example, a Bluetooth address), an Internet Protocol address, an identifier assigned to the device by an analyte monitoring system, a universal consensus identifier for broadcast-type devices, and the like. The sensor 1810 can change its identifier between its power-up and pairing with the first receiver 1820. If the sensor 1810 becomes disconnected from the first receiver 1820 during its active use, it can change its connection identifier upon disconnection or upon receiving a request for a new connection with the second receiver 1820.

[0191] As embodied herein, the sensor can support establishing a long-term connection pair by storing an encryption or authentication key for the data receiving device, or the data receiving device can support storing encryption and authentication keys for the sensor 1810 over time. For example, the sensor 1810 or the data receiving device can associate a connection identifier for the other party with an interaction regarding the encryption and authentication keys used by the other party. In doing so, the sensor 1810 can avoid a new authentication pairing with the data receiving device and can more quickly establish a connection with the data receiving device due at least in part to being able to immediately proceed to the stage of exchanging information through the encrypted communication protocol described herein. After a connection is successfully established, the two devices can refrain from broadcasting the connection identifier and other information for establishing a new connection, and can communicate using an agreed-upon channel hopping scheme to reduce the opportunity for a third party to eavesdrop on the communication. As another example, the sensor 1810 can scan available connection points and predominantly select a connection with a device that may already be connected, such as a device with which it may have previously established an authenticated interaction. Scanning for and connecting to known devices reduces the opportunity for a malicious third party to eavesdrop on the authentication interaction when other trusted data receiving devices are within communication range.

[0192] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of software 1845 shown in Figure 19 configured for operation by the communications module 1840. Figure 19 illustrates an exemplary hierarchical organization of the software blocks 1845 described with respect to the exemplary embodiments herein. As embodied herein, all software blocks may be installed and executed only on the communications module 1840 (e.g., via the microcontroller 1843), installed and executed only on the ASIC 1830, and / or allocated between the communications module 1840 and the ASIC 1830.

[0193] As embodied herein, these software blocks are installed on the communication module 1840, and the ASIC 1830 is configured to have no embedded processor, no software or reprogrammable logic. Thus, by installing and running the software blocks on the communication module 1840, the sensor 1810 can utilize the processing capabilities of the communication module 1840 to reduce the duties of the ASIC 1830. The complexity of a suitable ASIC 1830 can be reduced such that the ASIC 1830 is configured to perform operations designated for itself and nothing else. Based on this limited complexity and functionality, the footprint of the ASIC 1830 in the sensor 1810 can be reduced. In addition, the ASIC 1830 does not necessarily need to be a general-purpose processor, which can improve the efficiency of the ASIC 1830 and the sensor 1810 as a whole.

[0194] Additionally or alternatively, one or more software blocks may be installed on or otherwise implemented by the ASIC 1830 such that the ASIC 1830 may be configured to have an embedded processor, reprogrammable logic, and memory (not illustrated). Thus, by installing and running at least some of the software blocks on the ASIC 1830 (e.g., in addition to installing some of the software blocks on the communications module 1840), the sensor 1810 may take advantage of the increased flexibility of the programmable ASIC 1830 and communications module 1840 to extend the usefulness of the sensor 1810 itself, at least in part due to the elimination of the need to replace the ASIC 1830 to add functionality to the ASIC 1830. For example, the ASIC 1830 may be updated through firmware and software updates (e.g., using a process similar to that described herein for updating the communications module 1840). Additionally, the ASIC 1830 in these embodiments may include a processor configured to execute more complex analyte detection and processing algorithms, allowing the sensor 1810 to use the combined processing capabilities of the ASIC 1830 and the communications module 1840.

[0195] The overall architecture of the software block 1845 is shown in Figure 19. The block labeled SDK 1890 below the dotted line resides in read-only memory and is formatted as such. All other software blocks that can be written by the manufacturer of the sensor 1810 are loaded into the one-time programmable (OTP) memory of the communications module 1840.

[0196] The lifetime manager software block 1905 may include software functions for managing the operation of the sensor 1810 over its entire lifetime. These software functions may include functions for updating counters related to active operation time of the sensor 1810, functions for managing sensor activation, insertion detection, updating the sensor state, and updating the sensor status. The data processing software block 1910 may include software functions for managing the data processing aspects of the sensor 1810. In particular, the communication module 1840 is responsible for the majority of the sensor's data processing, offloading a significant portion of the sensor's data processing requirements. These software functions may include functions for processing raw data after receiving a transmission, storing historical data, and sending current measurement data to an authorized receiving device. The NFC manager 1915 may include software functions for the operations related to sending and receiving NFC communications (e.g., through the ASIC 1830). These software functions may include functions for sending data to the ASIC NFC radio 1835, receiving data from the ASIC NFC radio 1835, and processing received commands.

[0197] The persistent memory manager 1920 may include software functions that manage memory storage in the memory 1841 of the communications module 1840. For example, the persistent memory 1841 may store diagnostic data related to the sensor 1810, as well as historical data of measurements recorded by the analyte sensing hardware 1855, interpreted by the ASIC 1830, and sent to the communications module 1840. These software functions may include functions related to recording the factory configuration of the sensor 1810, historical measurement data, sensor event records, sensor status data, managing RAM used by dynamic algorithms, managing access to and storage in various memory hardware including static and dynamic persistent RAM, dynamic system RAM, managing access to one-time programmable memory, and enabling access to persistent memory through an API. The error handler 1925 may include software functions, described in more detail herein, that manage handling of errors detected in implementations by the sensor 1810 (e.g., while recording measurements). The firmware update software block 1930 may include software functions that allow for remote updates and upgrades of the sensor's 1810 firmware.

[0198] The security software block 1935 may include software functions related to encryption and decryption of sensitive data stored by the communication module 1840, encryption and decryption of communications to and from the sensor 1810 (e.g., with the receiver 1820), and authentication of devices when communicating. The security software block 1935 may include functions related to management of secure and public keys used by the sensor 1810. The algorithm software block 1940 may include software functions that process and interpret raw measurement data reported by the analyte sensing hardware 1855 through the ASIC 1830. These software functions may include functions to process high speed data (e.g., instantaneous measurements) and low speed data (e.g., trends of multiple measurements), data quality access functions, functions to calculate current measurement results (e.g., instantaneous glucose measurements), and functions to calculate past measurement results (e.g., past glucose trends). The measurement software block 1945 may include software functions that directly manage the analyte sensing hardware 1855. The software functions can include functions to start and stop measurements and to configure the analog front end 1839 to interface with the analyte sensing hardware 1855. The stability testing software block 1950 can include software functions used to perform sensor testing during or after manufacturing.

[0199] The communication module 1840 may include one or more medium-range communication radios 1848 (e.g., having a longer range than the NFC radio 1835 of the ASIC 1830). As an example, the communication module 1840 may include a Bluetooth radio or a Bluetooth Low Energy ("BLE") radio. The software block 1845 may include software for managing the communication radios. As an example, the software block 1845 may include a BLE manager 1955. The manager 1955 may include software functions related to maintaining the BLE radios, such as BLE configuration, sending to the receiver 1820, receiving data from the receiver 1820, receiving commands (e.g., shutdown) from the receiver 1820, and processing advertisements, which is the manner in which the communication module 1840 attempts to identify devices with which it can attempt to establish a connection. In particular, parameters related to a BLE connection may include transmitter power, connection interval, slave latency, and monitor timeout. The transmitter power parameter may be controlled. The sensor 1810 can use the BLE connection parameter update procedure to request that the receiver 1820 use a preferred set of connection parameters. After the receiver 1820 completes the authentication process, the sensor 1820 can set its preferred parameters to request an update of the preferred connection interval, wait time, and monitor timeout. This update procedure can reduce power consumption by maximizing the amount of time the radio is in low power mode while maintaining a connection with the receiver 1820.

[0200] Similarly, the software block 1845 may include a BLE services software block 1960 having software functions that provide an interface that makes the BLE radio available to the computer hardware of the communication module 1840. These software functions may include a BLE logic interface and an interface parser. The BLE services provided by the communication module may include a generic access profile service, a generic attribute service, a generic access service, a device information service, a data transmission service, and a security service. The data transmission service may be a primary service used to transmit data such as sensor control data, sensor status data, analyte measurement data (past and current), and event log data. The sensor status data may include error data, current active time, and software state. As embodied herein, the sensor 1810 may be configured to send sensor status data to the connected receiver 1820 upon initial authenticated connection to the receiver 1820 or when the sensor status changes or upon request from the receiver 1820. The analyte measurement data can include information such as current and past raw measurements (e.g., blood glucose, temperature), current and past values ​​after processing by the communications module 1840 using appropriate algorithms, predictions and trends of measurement levels (e.g., trends in blood glucose levels or temperature levels), comparisons of other values ​​to patient-specific averages, invocation of actions determined by the communications module's algorithms (e.g., the communications module 1840 is responsible for secure calculations while the receiver acts simply as a display device), and other similar types of data.

[0201] The security services can be used to provide authentication for communicating with the sensor 1810 operation. Authentication can include challenge and response commands, challenge data commands, security credential data, and secure keys used therewith. The BLE stack 1965 can include additional software functions used by the BLE components of the communication module 1840.

[0202] The ASIC hardware abstraction layer 1900 may include software functions that allow the communications module to communicate with the ASIC 1830 through the serial-peripheral interface 300. As indicated by the arrows connecting the ASIC hardware abstraction layer 1900 to other components, the ASIC hardware abstraction layer 1900 includes various functions that allow the communications module 1840 to write to, read from, and control the ASIC 1830. For example, the ASIC hardware abstraction layer 1900 supports the ASIC driver 1970 to expose various functions of the ASIC 1830 to the communications module. The OTP emulator 1975 may include software functions that emulate and allow the communications module 1840 to access the OTP memory 1831 of the ASIC 1830, e.g., internal RAM and serial memory.

[0203] The core framework 1980 may include functions that underlie the basic operation of the ASIC 1830. These functions include the core operations necessary to enable the ASIC 1830 to execute, such as a processor scheduler, interrupt handlers, memory manager, and timer utilities. The hardware abstraction layer 1985 may include functions that interface with various low-level hardware components of the ASIC 1830. These functions include functions related to a boot sequencer, power manager, voltage monitor, and other hardware drivers.

[0204] For purposes of illustration and not limitation, reference is made to an exemplary embodiment of a physical and logical serial-to-peripheral interface 300 between the ASIC 1830 and the communication module 1840 shown in FIG. 20 for use with the subject matter of the present disclosure. The SPI logic interface is mapped to registers and register settings in the ASIC 1830. Certain registers in the ASIC 1830 are read-only. Additionally or alternatively, certain registers can be read and written. A specified operation allows the SPI dominant to read and write to the ASIC registers. The read-only logic interface elements (and the ASIC 1830 valid registers) include interrupt requests. The write-only logic interface elements (and the ASIC 1830 valid registers) include NFC response flags and error codes, NFC response valid payload, and NFC response data. The read-and-write logic interface elements (and the ASIC 1830 valid registers) include a unique identifier, calculation data, trimmed data, outlier status, temperature measurement value, measurement status, and current measurement result.

[0205] For example, as shown in FIG. 20, the ASIC hardware of the serial-peripheral interface 2000 includes the ASIC digital section 2010 and the serial-peripheral physical interface hardware 1833. The SPI hardware 1833 may include an SPI clock 2025. The SPI hardware of the communications module includes a digital section 2030. In the illustrated embodiment, one of the ASIC 1830 and the communications module 1840 is designated as an SPI dominant role, and the other is designated as an SPI submissive. In particular, the ASIC 1830 is SPI submissive and has a submissive logic interface 2040. The communications module 1840 is SPI dominant and has a dominant logic interface 2050. The submissive logic interface 2040 and the dominant logic interface 2050 are connected by a logic unit connection. The SPI logic interface 2000 specifies the connection between the ASIC 1830 and the communications module 1840 at the logic unit register level. The ASIC hardware abstraction layer 200 modules of software block 1845 form messages with parameters as SPI dominant, and the ASIC digital section 2010 includes registers and logic for reading and writing thereto. As embodied herein, the SPI clock frequency is set by the ASIC 1830 to the maximum allowed value (e.g., 3 MHz). Figure 20 further illustrates four wired SPI physical interfaces between the SPI hardware 1833 of the ASIC 1830 and the digital section 2030 of the communications module. The SPI physical interface includes a connection between the SEL pin 2061 of the ASIC 1830 and the corresponding pin 2071 of the communications module 1840, a connection between the CLK pin 2063 of the ASIC 1830 and the corresponding pin 2073 of the communications module 1840, a connection between the MOSI pin 2065 of the ASIC 1830 and the corresponding pin 2075 of the communications module 1840, and a connection between the MISO pin 2067 of the ASIC 1830 and the corresponding pin 2077 of the communications module 1840.For purposes of illustration and not limitation, exemplary sequences of reading and writing messages suitable for effecting various functions and use case scenarios of the system are described herein with reference to corresponding figures.

[0206] Additionally or alternatively, the analog front end 1839 of the ASIC 1830 may derive diagnostics based on monitoring current and voltage readings from various electrodes of the analyte sensing hardware 1855 (e.g., analyte sensors). FIG. 22 illustrates a diagram of the AFE 1839 showing the functionality of the analog front end 1839 between the analyte sensor 2210 and the PCB 2220 of the sensor 1810. As embodied herein, FIG. 22 shows the working electrode 2212, the reference electrode 2214, and the counter electrode 2216, and further shows that the analyte sensing element 2218 is between the working electrode 2212 and the reference electrode 2214. The counter electrode is coupled to a bandgap reference voltage V bg , which is then adjusted and then provided to the reference electrode 2214. The analyte sensing element 2218 provides an additional voltage to the working electrode 2212. The difference between the voltage at the working electrode 2212 and the voltage at the reference electrode 2214, referred to as the equilibrium voltage, is used to determine the amount of analyte present. The voltage at the reference electrode 2214 is also monitored. Between each of the working electrode 2212, reference electrode 2214, and counter electrode 2216, there may be one or more additional sources of resistance (not illustrated), such as the resistance of the traces connecting the sensor electrodes to the junction with the sensor connector and the resistance from the PCB connector to the electronics. The PCB provides a bandgap reference voltage V bgThe working electrode may include a transimpedance amplifier 2222 that may include a programmable offset from the input. The transimpedance amplifier may convert the current signal from the working electrode to a voltage at the output, but may remove the common mode voltage (e.g., WRK) to determine the true measurement. In an alternative embodiment, a differential amplifier 2400 may be used as shown in FIG. 24. Note that when using a differential amplifier 2400, strict matching between resistors may apply for it to function.

[0207] In an alternative embodiment, the sensor 1810 can include multiple working electrodes. FIG. 23 illustrates an example configuration of the sensor 1810. As embodied herein, FIG. 23 illustrates an example circuit 2300 including an analyte sensor 2310 having a first working electrode current 2311 (WRK_1) and a second working electrode current 2312 (WRK_2). The analyte sensor 2310 further includes a reference electrode 2314 (REF) and a counter electrode 2316 (CTR) positioned in the same manner as in the analyte sensor 2210. The current from each of the working electrodes can be fed to transimpedance amplifiers 2322 and 2323 as shown in FIG. 22. Each transimpedance amplifier is coupled to a bandgap reference voltage V bg The transimpedance amplifier can convert the current signal from the working electrode to a voltage at the output. In an alternative embodiment, a differential amplifier such as that shown in FIG. 24 can be used, but the common mode voltage (e.g., WRK) can be removed to determine the true measurement. In an alternative embodiment, one or more differential amplifiers such as differential amplifier 2400 shown in FIG. 24 can be used.

[0208] As embodied herein, the analog front end 1839 can be configured to monitor current and voltage from at least the working electrode (e.g., working electrode 2212) and the counter electrode (e.g., counter electrode 2216). The analog front end 1839 can monitor for low working currents. The analog front end 1839 or the ASIC 1830 can be configured with a minimum working current threshold for the analyte sensor 1810 to remain operational after insertion into a patient. In addition to this, the analog front end 1839 can monitor for low working currents, particularly for a predefined period of time after insertion of the sensor by a user. In addition to monitoring the working current for a minimum working current threshold, the analog front end 1839 and the ASIC 1830 can monitor for working current values ​​in a threshold range of a target working current value. The analog front end 1839 can monitor for even higher working currents. The analog front end 1839 or ASIC 1830 can be configured with a maximum working current threshold that corresponds to a value less than the saturation of the analyte sensor, the point at which the sensor value cannot be considered accurate. Additionally, the analog front end 1839 can monitor for a low counter electrode voltage. In particular, the analyte sensor voltage between the working and counter electrodes can be maintained, for example, by a servo amplifier that adjusts the voltage at the counter electrode in response to negative feedback from the reference electrode. As the state of the analyte sensor changes, the counter electrode voltage is automatically adjusted to maintain the reference voltage at a predetermined amount, which can be used to maintain the target equilibrium voltage in an appropriate range. The analog front end 1839 or ASIC 1830 can be configured with a minimum counter electrode voltage threshold to keep the analyte sensor operating properly. Additionally, the analog front end 1839 can monitor for a high counter electrode voltage. In particular, since the analyte sensor functions in part by measuring the voltage difference between the working and counter electrodes, the voltage from the counter electrode may not be higher than the voltage from the working electrode for the analyte sensor to function properly.The analog front end 1839 or ASIC 1830 can be configured with appropriate maximum counter electrode voltage thresholds. These analog front end diagnostic tests can be used to evaluate analyte sensor failure modes, including sensor connection problems.

[0209] The balance voltage can be maintained using a hardware forced or programmable balance voltage source. The purpose of the programmable balance voltage source is to bias the difference between the voltage at the working electrode and the voltage at the reference electrode to ensure that the measurement range is in a target range suitable for analyte measurement. To change the balance voltage using a hardware forced balance voltage source, the resistor network that sets the balance voltage must be recalculated and changed to the new intended balance voltage. Thus, to change the balance voltage, the board is disassembled and resistors are replaced with new values, which can be inconvenient when resistors with suitable values ​​are not available. On the other hand, a programmable balance voltage allows for adjustment of a high sensitivity analyte sensor according to conditions that develop over the life of the analyte sensor. For example, a microprocessor capable of setting the balance voltage can control the balance voltage generation circuit by outputting the required voltage through its DAC pin. This allows for fast automatic calibration of the balance voltage. The DAC settings can be optimized using software routines and stored for later use.

[0210] FIG. 25 illustrates an exemplary circuit that can be used as a variable floating balance voltage generator. The circuit 2500 uses four resistors 2511, 2512, 2513, and 2514, an N-channel MOSFET 2520, and two operational amplifiers 2531 and 2532, one acting as a current source 2531 and the other as an inverting amplifier 2532, as shown in FIG. 25. The balance voltage is set by DAC1 2541 and DAC2 2542 from a microprocessor. The operational amplifier 2532 will invert the voltage from DAC2 2542 to a voltage equal to the negative voltage of DAC2 2542. The operational amplifier 2531 is configured as a current source that is programmed with its positive output. The difference between "balance high" 2551 and "balance low" 2552 is the balance voltage, which is controlled by the current flowing through resistor 2511 (shown in FIG. 26). The voltage at "balance high" 2552 is driven by the amplifier shown in FIG. 26, which also controls the voltage at the working electrode of the sensor. An operational amplifier 2531 and a MOSFET 2520 will control the voltage at 2560 to be equal to the voltage at 2561. The voltage across resistor 2512 is controlled by the settings for DAC1 2511 and DAC2 2512. The current flowing through resistor 2512 is the same as the current flowing through resistor 2511. In this way, the balance voltage can be controlled independently of the voltage at WRK. With this circuit, when the voltage at WRK is adjusted due to a change in the sensor current, the balance voltage will remain unchanged even if the voltage at WRK changes.

[0211] 26 illustrates an example configuration of a sensor in a measurement configuration with a floating variable balance voltage circuit (e.g., circuit 2500). The balance voltage is measured from the WRK and REF electrodes and is equal to the voltage measured from the balance high and balance low. The analyte sensor 2510 is a sensor having a chemical agent that reacts with the analyte sensor during use as described herein.

[0212] FIG. 27 illustrates an example configuration 2700 of a sensor in a calibration configuration with a floating variable balance voltage circuit (e.g., circuit 2500). During calibration, a simulated analyte sensor 2710 can be used with two resistors 2711 and 2712 as shown in FIG. 27. A digital voltmeter (DVM) 2720 will measure the voltage between WRK and REF and return this measurement to a microprocessor 2730 to adjust DAC1 and DAC2 to bring the balance voltage to the desired value. In the sensor measurement configuration, the balance voltage will be the one already set during calibration and the WRK operational amplifier will source a current through resistor 2511 of FIG. 25.

[0213] When an analyte sensor 2610 is connected to the circuit 2600 of FIG. 26, the portion of the sensor connected between WRK2621 and REF2621 will generate a current when in contact with an analyte. The variable balance voltage can allow the sensor to detect a variety of analytes by adjusting the response current in both the positive and negative domains. The current is expressed as Z CTR 2631 and R meas 2632. The voltage at the CTR electrode 2623 will vary depending on the current generated by the analyte sensor 2610, and therefore the voltage at the REF electrode 2622 will vary depending on R meas 2632 and Z CTR2631. Thus, a floating balance voltage is provided. The feedback loop of the REF operational amplifier 2642 includes the WRK operational amplifier 2642 and the resistor 2511. The voltage output of the REF operational amplifier 2642 reaches the positive terminal of the WRK operational amplifier 2641, which in turn adjusts the negative terminal of the WRK operational amplifier 2641 to match the positive terminal, and the feedback loop of the REF operational amplifier 2642 continues through the resistor 2511, which has a voltage equal to the digitally set balance voltage. Due to this feedback loop, the voltage at the REF electrode 2622 and the voltage at the WRK electrode 2621 differ by the voltage across the resistor 2511, which is the balance voltage set and calibrated by the microprocessor 2650.

[0214] Figures 28-30 illustrate an example configuration of a circuit configured to sample signals from a multi-analyte sensor. Circuit 2800 shown in Figures 28A-B includes a multi-analyte sensor 2802, thirteen resistors 2832a-c, 2836, 2842, 2846a-f, and 2854a-b, seven capacitors 2834a-c, 2838, 2840, 2844, and 2848, and operational amplifiers 2811, 2813, 2815, and 2817. Circuit 2800 can be used to measure glucose levels. The resistance of resistors 2832a-2832c can be R1, the resistance of resistor 2836 can be R2, the resistance of resistor 2842 can be R3, the resistance of resistors 2846a-2846f can be R4, and the resistance of resistors 2854a-2854b can be R5. Any of these resistors can be different values ​​based on the circuit 2800. The capacitance of capacitors 2834a-2834c can be C1, the capacitance of capacitor 2838 can be C2, the capacitance of capacitor 2840 can be C3, the capacitance of capacitor 2844 can be C4, and the capacitance of capacitor 2848 can be C5. Any of these capacitors can be different values ​​based on the circuit 2800.

[0215] 28A-28B, as embodied herein, a multi-analyte sensor 2802 includes a first working electrode 2804 (WRK_1), a second working electrode 2806 (WRK_2), a reference electrode 2808 (REF), and a counter electrode 2810 (CTR). A pair of one of resistors 2832a-2832c and one of capacitors 2834a-2834c is coupled to each of the first working electrode current 2804, the second working electrode current 2806, and the counter electrode 2810 for electrostatic discharge (ESD) / electromagnetic interference (EMI) rejection purposes. A resistor 2836 and a capacitor 2838 are coupled to the reference electrode 2808 for ESD / EMI rejection purposes. A first working electrode bias 2812 can be determined from a negatively balanced bias amplifier as described herein and shown in FIG. 28B. The first working electrode bias 2812 can be a predetermined voltage of the reference electrode 2808. The predetermined voltage is based on the test platform of the circuit 2800.

[0216] 28A-B, operational amplifier 2811, resistor 2842, and capacitor 2844 are configured as a transimpedance amplifier. The transimpedance amplifier receives a working input signal 2814 from second working electrode 2806 and a bias offset Vbias (e.g., WRK_0 2816). WRK_0 2816 can be a predetermined voltage of reference electrode 2808. The predetermined voltage is based on a test platform for circuit 2800. The transimpedance amplifier converts the current from second working electrode 2806 into a voltage and the bias offset plus the current from second working electrode 2806 is * Get the resistance of the transimpedance amplifier. For example, the output of the transimpedance amplifier is Vbias+I_WRK(x) * Rtz, which is the action signal WRK_TZ2822 of the transimpedance amplifier. The time constant of the transimpedance amplifier is R3 * It is possible to set C4=T1.

[0217] As embodied herein, the output of the transimpedance amplifier is the input to a differential amplifier comprised of resistors 2846a-2846d, a capacitor 2848, and an operational amplifier 2813. The differential amplifier subtracts a bias offset (Vbias) from the output WRK_TZ 2822 from the transimpedance amplifier and calculates the current from the second working electrode 2806. * Resistance of the transimpedance amplifier (e.g., I_WRK(x) * Rtz), which is used as the input to the analog-to-digital converter. The input DIFF+ 2826 is WRK_TZ 2822 divided by 2, and the input DIFF- 2824 is the bias offset Vbias through resistor 2846b, a summing resistor. The output of the differential amplifier is the working output (WRK_OUT 2828). For example, WRK_OUT 2828 is (WRK_TZ 2822 / 2) * (1+R4 / R4)-(R4 / R4) * Vbias, where Vbias is WRK_0 2816. The high resistance of resistors 2846a-2846f is used to minimize loading on WRK_0 2816 or Vbias. The time constant of the differential amplifier may be T2.

[0218] 28A, as embodied herein, REF_0 2830 can be coupled to a negative balanced bias amplifier comprised of resistors 2846e-2846f, 2854a-2854b and operational amplifiers 2815 and 2817. Referring to FIG. 28B, a negative balanced bias amplifier is shown where the circuit subtracts a predetermined voltage from REF 2808 to directly bias the first working electrode 2804. One input to the negative balanced bias amplifier is REF_0 2830 connected to the "+" input of operational amplifier 2815, and the other input is a negative balanced reference value NPREF 2850 summed into the inverting input of operational amplifier 2815. The resistance ratio of resistors 2846e and 2854a, k=R4 / R5=resistance ratio, determines the balance that is subtracted from REF 2830 as NPREF 2850 / (k+1). This gives a nominal NPREF 2850 called V1, which is V2 subtracted from REF 2830. The output of operational amplifier 2815 is a slightly boosted REF 2830 plus a bias signal BIAS_BST 2852. Operational amplifier 2817 is a unity gain buffer. The output of operational amplifier 2817 is the first working electrode bias WRK1_BIAS 2812, which is a slightly scaled down version of BIAS_BST 2852 called BIAS_DIV 2856. For example, BIAS_DIV 2856 = WRK1_BIAS 2812 = k * BIAS_BST2852 / (k+1)=REF2830-k * NPREF2850 / (k+1) holds.

[0219] 29A-B, as embodied herein, an exemplary circuit 2900 includes a multi-analyte sensor 2902, thirteen resistors 2932a-c, 2936, 2942, 2946a-f, and 2954a-b, seven capacitors 2934a-c, 2938, 2940, 2944, and 2948, and operational amplifiers 2911, 2913, 2915, and 2917. Circuit 2900 can be used to measure ketone levels. The resistance of resistors 2932a-2932c can be R1, the resistance of resistor 2936 can be R2, the resistance of resistor 2942 can be R3, the resistance of resistors 2946a-2946f can be R4, and the resistance of resistors 2954a-2954b can be R5. Any of these resistors can be different values ​​based on the circuit 2900. The capacitance of capacitors 2934a-2934c can be C1, the capacitance of capacitor 2938 can be C2, the capacitance of capacitor 2940 can be C3, the capacitance of capacitor 2944 can be C4, and the capacitance of capacitor 2948 can be C5. Any of these capacitors can be different values ​​based on the circuit 2900.

[0220] 29A-B, the multi-analyte sensor 2902 includes a first working electrode 2904 (WRK_1), a second working electrode 2906 (WRK_2), a reference electrode 2908 (REF), and a counter electrode 2910 (CTR). A pair of one of resistors 2932a-c and one of capacitors 2934a-c is coupled to each of the first working electrode current 2904, second working electrode current 2906, and counter electrode 2910 for electrostatic discharge (ESD) / electromagnetic interference (EMI) rejection purposes. A resistor 2936 and capacitor 2938 are coupled to the reference electrode 2908 for ESD / EMI rejection purposes.

[0221] As embodied herein, the first working electrode bias 2912 can be determined from a negative balanced bias amplifier as described herein and shown, for example, in FIG. 29B. The first working electrode bias 2912 can be a predetermined voltage of the reference electrode 2908. The predetermined voltage is based on a test platform of the circuit 2900. The operational amplifier 2911, resistor 2942, and capacitor 2944 are configured as a transimpedance amplifier. The transimpedance amplifier receives a working input signal 2914 from the first working electrode 2904 and a bias offset Vbias (e.g., WRK_1Bias 2912). The transimpedance amplifier converts the current from the first working electrode 2904 to a voltage and converts the bias offset plus the current from the first working electrode 2904 to a voltage. * Get the resistance of the transimpedance amplifier. For example, the output of the transimpedance amplifier is Vbias+I_WRK(x) * Rtz, which is the action signal WRK_TZ2922 of the transimpedance amplifier. The time constant of the transimpedance amplifier is R3 * C4=T3 can be set.

[0222] 29A-29B, the output of the transimpedance amplifier, WRK_TZ 2922, is input to a differential amplifier comprised of resistors 2946a-2946d, a capacitor 2948, and an operational amplifier 2913. The differential amplifier subtracts a bias offset (Vbias) from the output WRK_TZ 2922 from the transimpedance amplifier and calculates the current from the first working electrode 2904 * the resistance of the transimpedance amplifier (e.g., I_WRK(x)). * Rtz), which is used as the input to the analog-to-digital converter. Input DIFF+ 2926 is WRK_TZ 2922 divided by 2, and input DIFF- 2924 is the bias offset Vbias through resistor 2946b, a summing resistor. The output of the differential amplifier is the working output (WRK_OUT 2928). For example, WRK_OUT 2928 is (WRK_TZ 2922 / 2) *(1+R4 / R4)-(R4 / R4) * 29A, REF_0 2930 may be coupled to a negatively balanced bias amplifier comprised of resistors 2946e-2946f, 2954a-2954b and operational amplifiers 2915 and 2917. The high resistance of resistors 2946a-2946f may be used to reduce or minimize the load on WRK_1Bias 2912 or Vbias. The time constant of the differential amplifier may be T1. Referring to FIG. 29A, REF_0 2930 may be coupled to a negatively balanced bias amplifier comprised of resistors 2946e-2946f, 2954a-2954b and operational amplifiers 2915 and 2917.

[0223] 29B, as embodied herein, a negative balanced bias amplifier is shown in which the circuit subtracts a predetermined voltage from REF 2908 to bias the first working electrode 2904 through a transimpedance amplifier. One input to the negative balanced bias amplifier is REF_0 2930 connected to the "+" input of operational amplifier 2915, and the other input is a negative balanced reference value NPREF 2950 summed into the inverting input of operational amplifier 2915. The resistance ratio k=R4 / R5=resistor ratio of resistors 2946e and 2954a determines the balance that is subtracted from REF 2930 as NPREF 2950 / (k+1). This gives a nominal NPREF 2950 of V1, which has V2 subtracted from REF 2930. The output of operational amplifier 2915 is a slightly boosted REF 2930 plus a bias signal BIAS_BST 2952. The operational amplifier 2917 is a unity gain buffer. The output of the operational amplifier 2917 is the first working electrode bias WRK1_BIAS 2912, which is a slight scaled down version of BIAS_BST 2952 called BIAS_DIV 2956. For example, BIAS_DIV 2956=WRK1_BIAS 2912=k * BIAS_BST2952 / (k+1)=REF2930-k * NPREF2950 / (k+1) holds.

[0224] 30, an exemplary circuit 3000 includes a multiple analyte sensor 3002, nine resistors 3028a-3028c, 3032, 3038, and 3042a-3042d, seven capacitors 3030a-3030c, 3034, 3036, 3040, and 3044, and operational amplifiers 3011 and 3013. The circuit 3000 can be used to measure lactate levels. The resistance of resistors 3028a-3028c can be R1, the resistance of resistor 3032 can be R2, the resistance of resistor 3038 can be R3, and the resistance of resistors 3042a-3042d can be R4. Any of these resistors can be different values ​​based on the circuit 3000. The capacitance of capacitors 3030a-3030c may be C1, the capacitance of capacitor 3034 may be C2, the capacitance of capacitor 3036 may be C3, the capacitance of capacitor 3040 may be C4, and the capacitance of capacitor 3044 may be C5. Any of these capacitors may have different values ​​based on the circuit 3000.

[0225] As embodied herein, the multi-analyte sensor 3002 includes a first working electrode 3004 (WRK_1), a second working electrode 3006 (WRK_2), a reference electrode 3008 (REF), and a counter electrode 3010 (CTR). A pair of one of resistors 3028a-3028c and one of capacitors 3030a-3030c is coupled to each of the first working electrode current 3004, the second working electrode current 3006, and the counter electrode 3010 for electrostatic discharge (ESD) / electromagnetic interference (EMI) rejection purposes. A resistor 3032 and a capacitor 3034 are coupled to the reference electrode 3008 for ESD / EMI rejection purposes. The operational amplifier 3011, resistor 3038, and capacitor 3040 are configured as a transimpedance amplifier. The transimpedance amplifier receives a working input signal 3012 from the first working electrode 3004 and a WRK_0 3014 signal from the second working electrode 3006. The transimpedance amplifier converts the current from the first working electrode 3004 to a voltage, taking the bias offset plus the current from the first working electrode 3004 * the resistance of the transimpedance amplifier. For example, the output of the transimpedance amplifier is Vbias + I_WRK(x). * Rtz, which is the action signal WRK_TZ3021 of the transimpedance amplifier. The time constant of the transimpedance amplifier is R3 * It is possible to set C4=T4.

[0226] 30, as embodied herein, the output of the transimpedance amplifier, WRK_TZ 3021, is input into a differential amplifier comprised of resistors 3042a-3042d, a capacitor 3044, and an operational amplifier 3013. The differential amplifier subtracts a bias offset (Vbias or WRK_0 3014) from the output from the transimpedance amplifier, WRK_TZ 3021, and calculates the current from the first working electrode 3004 * the resistance of the transimpedance amplifier (e.g., I_WRK(x)). *Rtz), which is used as the input to the analog-to-digital converter. Input DIFF+ 3022 is WRK_TZ3021 divided by 2, and input DIFF- 3020 is the bias offset Vbias through resistor 3042b, a summing resistor. The output of the differential amplifier is the working output (WRK_OUT 3024). For example, WRK_OUT 3024 is (WRK_TZ3021 / 2) * (1+R4 / R4)-(R4 / R4) * Vbias, where Vbias is WRK_0 3014. The high resistance of resistors 3042a-3042d is used to minimize the load on Vbias. The time constant of the differential amplifier may be T5.

[0227] For purposes of illustration and not limitation, as embodied herein, circuits 2800, 2900, and 3000 may utilize respective differential amplifiers to subtract a bias offset from the transimpedance amplifier output to reduce the signal to the range of the A / D converter. However, after subtracting the bias offset from the transimpedance amplifier output, there may be a residual error that depends on the bias voltage, and it may be advantageous to remove this residual error by calibration. The calibration may include at least a two-point offset calibration for the WRK(X) channel. For common mode operational amplifier characteristics, a three-point calibration may be used. For example, as shown in FIG. 31, a three-point calibration may result in a linear fit from .2V to 1V, as shown in graph 3100, and another linear fit from 1V to 2V.

[0228] The calibration and operating current equations can include various parameters including, but not limited to, CO (counter offset, zero current input), CS (counter "slope" which is a high calibration point with current input rather than slope), REFR and thermistor calibration parameters, calibration parameters related to common mode offset, and current calibration parameters related to slope. The calibration parameters related to common mode offset can include the WRK0 channel (internal A / D input) common mode voltages (NW0cm1, NW0cm2, NW0cm3) and the WRK(X) channel ("CNTR" A / D input) offsets (NWxos1, NWxos2, and NWxos3). The current calibration parameters related to slope (i.e., A / D counts related to slope calibration current input) can include the WRK(X) channel ("CNTR" A / D input) (NWxcurr). The three-point offset calibration equations can include the sensor offset calibration slope equation, the in-run sensor offset equation, the sensor current calibration slope equation, and the in-run sensor current equation. The sensor offset calibration slope equation can include MWxos1 = (NWxos2 - Nwxos1) / (NW0cm2 - NW0cm1), where WRK(X) is the offset slope 1 (delta WRK(X) counts) / (delta WRK0 counts). The sensor offset calibration slope equation can include MWxos2 = (NWxos3 - Nwxos2) / (NW0cm3 - NW0cm2), where WRK(X) is the offset slope 2 (delta WRK(X) counts) / (delta WRK0 counts). The in-run sensor offset equation can include NWxos = NWxos2 + MWxos1 for NW0cm < NW0cm2 (WRK0 A / D reading < WRK0 calibration point #2), where WRK(X) is the offset along the WRK(X) offset line 1 of slope 1. The in-run sensor offset equation can include NWxos = NWxos2 + NWxos2 for NW0cm ≧ NW0cm2 (WRK0 A / D reading ≧ WRK0 calibration point #2). * (NW0cm - NW0cm2), where WRK(X) is the offset along the WRK(X) offset line 1 of slope 1. The in-run sensor offset equation can include NWxos = NWxos2 + NWxos2 for NW0cm ≧ NW0cm2 (WRK0 A / D reading ≧ WRK0 calibration point #2). *(NW0cm-NW0cm2), where WRK(X) offsets along line 2 with a WRK(X) offset of slope 2. For the run-time sensor offset equation, calibration point NWxos2 can be common to both line 1 and line 2. The sensor current calibration slope equation can include MWxcurr=IWRK(X)_CAL / (NWXcurr-Nwxos2), where WRK(X) is the sensor current slope (pA / counts). The sensor current calibration slope equation can include IWRK(X)_CAL=I1 for circuit 1200. The sensor current calibration slope equation can include IWRK(X)_CAL=I2 for circuits 1100, 3000. The run-time sensor current equation can include IWRK(X)=MWxcurr * (NWRK(X)-Nwxos).

[0229] 32-33 illustrate an exemplary configuration of a circuit configured to sample signals from a multi-analyte sensor using an ASIC. In turn, circuit 3200 shown in FIGS. 32A-32B includes a multi-analyte sensor 3202, two ASICs 3212a-3212b, eight capacitors 3214a-3214d, 3220a-3220b, 3224, 3226, five resistors 3216, 3222, 3230, 3232, 3234, a thermistor 3218, and an antenna 3228. Circuit 3200 can be used to measure ketone levels, lactose levels, and glucose levels. In certain embodiments, ASIC_1 3212a can be used to measure ketone levels or lactose levels, where a load can be applied to resistor 3216 to perform a measurement regarding ketone levels. In certain embodiments, ASIC_2 3212b can be used to measure glucose levels. The capacitance of capacitors 3214a-3214d can be C6, the capacitance of capacitors 3220a-3220b can be C7, the capacitance of capacitor 3224 can be C8, and the capacitance of capacitor 3226 can be C9. Any of these capacitors can be different values ​​based on the circuit 3200. The resistance of resistor 3216 can be R6, the resistance of resistor 3222 can be R7, the resistance of resistor 3230 can be R2, the resistance of resistor 3232 can be R8, and the resistance of resistor 3234 can be R9. Any of these resistors can be different values ​​based on the circuit 3200.

[0230] 32A-32B, as embodied herein, the multi-analyte sensor 3202 includes a first working electrode 3204 (WRK_1), a second working electrode 3206 (WRK_2), a reference electrode 3208 (REF), and a counter electrode 3210 (CTR). Capacitors 3214a-3214d can be coupled to each of the first working electrode current 3204, the second working electrode current 3206, the reference electrode 3208, and the counter electrode 3210. The ASIC_1 3212a can include multiple pins. In a particular embodiment, the ASIC_1 3212a can include a thermistor pin, a pin for the first working electrode 3204 (WRK_1), a reference pin, a counter pin, a VSS pin, a VPP pin, a VBAT pin, a BLE_EN pin, an ANT1 pin, and an ANT2 pin. In a particular embodiment, the ASICs 3212a, 3212b can have ESD protection of ±2KV HBM for each of its pins. With low leakage inputs, the ASICs 3212a, 3212b can have ±500V HBM for each of its pins. The first working electrode 3204 can be coupled to a working electrode pin of the ASIC_1 3212a through a resistor 3216. The reference electrode 3208 can be coupled to a reference pin of the ASIC_1 3212a. The counter electrode 3210 can be coupled to a counter electrode pin of the ASIC_1 3212a. The second working electrode 3206 can be coupled to a working electrode pin of the ASIC_2 3212b shown in FIG. 32B. The thermistor pin of the ASIC_1 3212a can be coupled to the thermistor 3218. The VBAT pin can be coupled to a capacitor 3220a. The BLE_EN pin is coupled to a resistor 3222 and may be coupled to BLE_EN 3230. The ANT1 and ANT2 pins may be coupled to two capacitors 3224, 3226 and an antenna 3228 in a particular configuration. Although a particular configuration is shown in circuit 3200, other configurations of the components of 3200 are contemplated. ASIC_2 3212b may include similar pins as ASIC_1 3212a. The thermistor pin of ASIC_2 3212b may be coupled to a resistor 3230.The reference pin of ASIC_2 3212b may be coupled to the counter pin through a resistor 3232. The VBAT pin of ASIC_2 3212b may be coupled to a capacitor 3220b. The ANT2 pin of ASIC_2 3212b may be coupled to a resistor 3234.

[0231] Referring to Fig. 33, a circuit 1600 is shown. The circuit 1600 shown in Fig. 33 can include an ASIC 1602 and a sensor 1604. The ASIC 1602 can have a counter electrode pin, a reference pin, a first working electrode pin, and a second working electrode pin. The sensor 1604 can include a counter electrode output 1606 coupled to the counter electrode pin of the ASIC 1602, a reference output 1608 coupled to the reference pin of the ASIC 1602, a first working electrode output 1610 coupled to the first working electrode pin of the ASIC 1602, and a second working electrode output 1612 coupled to the second working electrode pin of the ASIC 1602.

[0232] The multiple analyte sensor 3202, 1604 described in the circuit 3200, 1600 can be a four terminal multi-analyte electrochemical biosensor. The sensor 3202, 1604 can be exposed to body interstitial fluid and properly biased to provide two independent current flows from a corresponding first working electrode 3204, 1610 and a corresponding second working electrode 3206, 1612 to its corresponding counter electrode 3210, 1606. The power source of the circuit 3200, 1600 can be a battery. By way of example and not limitation, the power source of the circuit 3200, 1600 can be a 1.55V highly discharged silver oxide battery. The potassium electrolyte can provide a low equivalent series resistance (ESR). This can help support current draw during Bluetooth Low Energy (BLE) transmissions. The ASIC 3212a-3212b, 1602 performs analyte measurements, temperature measurements, and diagnostic measurements and can incorporate an NFC radio. The NFC radio can be used by the user to activate the patch. In certain embodiments, the NFC radio can be used to scan the ASICs 3212a-3212b, 1602 to obtain historical specimen results therefrom. The BLE radio can provide a wireless interface to a reader for the user to obtain results. Result data from the ASICs 3212a-322b, 1602 can be periodically communicated to the radio for storage and transmission. By way of example and not limitation, result data can be communicated to the BLE radio every minute.

[0233] In a particular embodiment, the circuit 3200 can measure the current delivered from the sensor 3202 using two ASICs 3212a-b. The combination of analytes measured can vary depending on the target product. The first working electrode 3204 and the second working electrode 3206 can have transimpedance amplifiers capable of simultaneously measuring maximum current. The reference electrode 3208 can provide an electrochemical reference potential for the sensor 3202. The ASICs 3212a-b can buffer the voltage on the reference electrode 3208 using a high impedance low leakage amplifier and set independent bias voltages on each of the working electrodes 3204, 3206. In a particular embodiment, the bias voltages can be programmable bias voltages that can be set to fixed values ​​by the BLE radio. The circuit 3200 can measure skin temperature using a thermistor 3218. The compliance voltages of the reference electrode 3208 and the counter electrode 3210 can be measured and used as diagnostics within ASIC_1 3212a.

[0234] In a particular embodiment, the first working electrode 3204 and the second working electrode 3206 can use a predetermined sampling window to filter out undesired low frequency and substrate effect interference. By way of example and not limitation, a sampling window of 32 seconds can be used. In a particular embodiment, the circuit 3200 can have a measurement interval. A measurement interval determined by a time constraint can be provided. The two working electrodes 3204, 3206 can be sampled simultaneously. There may be an offset drift associated with measurements using the ASICs 3212a-3212b. The ASICs 3212a-3212b can compensate for this offset in real time. The BLE radio can periodically read conversion values ​​for the first working electrode 3204, the second working electrode 3206, the temperature, and the potential of the counter electrode 3210.

[0235] In a particular embodiment, the circuit 3200 can have a signal chain serving two analyte channels (e.g., first working electrode 3204, second working electrode 3206), a temperature channel, and a channel for measuring counter electrode voltage as a diagnostic indicator. This measurement channel can be used to achieve a battery voltage monitor. In a particular embodiment, the circuit 3200 can be calibrated for offset and gain during PCBA manufacturing testing. The measurement range can be I1 to I2 (high) and I1 to I3 (low). Each of the first working electrode 3204 and the second working electrode 3206 can have a selectable high range and a low range. The resolution can have a bit minimum. By way of example and not limitation, the resolution can be a 16 bit minimum. The measurement time can have a maximum duration. The measurement time can be the time to complete both the analyte, temperature measurement and the counter electrode measurement. By way of example and not limitation, the maximum duration can be 50 seconds. In certain embodiments, the first working electrode 3204 and the second working electrode 3206 can be capable of sampling simultaneously for a predetermined period of time. By way of example and not limitation, the first working electrode 3204 and the second working electrode 3206 can be capable of sampling simultaneously for 32 seconds. In certain embodiments, the measurement channel can be calibrated at manufacture to within an accuracy level of zero input current and an appropriate reference point. The range of the measurement channel can be determined by one or more factors including the analyte measurement range, the variation in sensor sensitivity across all sensor lots, and temperature sensitivity. The sensor sensitivity can be determined by the lot sensor sensitivity in nA / (mmol / L) and temperature.

[0236] In certain embodiments, bandwidth limiting can be used for the circuit 3200. Bandwidth limiting can enable high frequency filtering to ensure that extraneous high frequency noise sources do not couple into the measurement channel and result in spurious signals. Bandwidth limiting can be implemented by the ASICs 3212a-3212b.

[0237] In certain embodiments, the sensor 3202 may use a bias between the reference electrode 3208 and the working electrodes 3204, 3206. This bias may be used to cause desired responses to occur and prevent undesired responses from occurring. Individual measurement channels may be independently programmed for different bias voltages for various analytes. By way of example and not limitation, a measurement channel for glucose measurement may have a different bias voltage than a ketone measurement channel. In certain embodiments, the bias is static, set during start-up, and cannot be changed during use of the circuit 3200. In certain embodiments, each channel of the circuit 3200 may be independently configurable.

[0238] In a particular embodiment, the ASICs 3212a-3212b may have a timer that will time the operation of a state machine that performs the calibration process. The timer may have a threshold accuracy to ensure that the calibration process is completed within a predetermined period of time. The timer may be restarted after the predetermined period of time. By way of example and not limitation, the calibration process may be 50 seconds and the timer may be restarted every minute.

[0239] 33, the circuit 3300 can have similar attributes and functions as the circuit 3200, with the ASIC 3302 performing both the functions of the ASIC 3212a and the ASIC 3212b. In certain embodiments, when the sensor 3304 is immersed in an analyte solution, a current can flow from the working electrodes 3310, 3312 and is measured by the ASIC 3302. In certain embodiments, the current can be measured on the high side to distinguish between the two currents from the working electrodes 3310, 3312. The circuit 3300 can use some different measurement topologies to interface the ASIC 3302 to the sensor 3304. By way of example and not limitation, a potentiostat can be used. A reference electrode 3308 can provide an electrochemical reference potential for the sensor 3304. The ASIC 3302 can buffer the voltage on the reference electrode 3308 using a high impedance low leakage amplifier and set a bias voltage on the working electrodes 3310, 3312 relative to the reference electrode 3308. The bias voltage can be set to a fixed value. This value can be set by a DAC programmed through a resistor or by a pair of fixed resistors external to the ASIC 3302. In certain embodiments, the circuit 3300 can use a transimpedance amplifier to measure the current flowing out of the working electrodes 3310, 3312. The circuit 3300 can use a high impedance buffer amplifier to measure the potential on the reference electrode 3308. The reference electrode 3308 signal can be connected to a servo amplifier to drive the counter electrode 3306 to a voltage that puts the reference electrode 3308 at the desired bias voltage relative to the working electrodes 3310, 3312. In certain embodiments, the bias of the sensor 3304 can be set by a resistor or an external resistor.

[0240] In certain embodiments, the sensor bias of the ASIC 3302 can be monitored by measuring the voltage on the working electrodes 3310, 3312. The working electrode voltage measurement can be performed every minute. In certain embodiments, if either of the working electrodes 3310, 3312 exceeds a predetermined threshold, the measurement for that minute can be excluded. The determination of whether or not it has been exceeded can be made by software running on the BLE radio of the circuit 3300. The ASIC 3302 can measure the working voltage or the counter electrode voltage to provide a diagnostic measurement. In certain embodiments, the measurement channels of the circuit 3300 can be individually enabled with a configurable sample rate and a configurable number of samples. This configuration can persist until reconfigured through the SPI interface. The measurement configuration can include a manufacturing stability test, in which the glucose channel is measured every second to collect data. Additionally or alternatively, as embodied herein, the measurement configuration can include a manufacturing calibration, in which the glucose channel is measured with an injected current to determine the slope and intercept of the glucose measurement. Additionally or alternatively, the measurement configuration may include a production measurement sequence that includes diagnostics.

[0241] In certain embodiments, the circuit 3300 can have an analog signal chain that can be for a glucose channel, one temperature channel, and a channel for measuring the working voltage as a diagnostic indicator.

[0242] In a particular embodiment, the bandwidth limiting of the circuit 3300 can be implemented as a combination of external analog filtering and internal digital filtering. An external ceramic capacitor can be used. The capacitance of the external ceramic capacitor can be less than 10 μF. A voltage comparator can be used to perform battery monitoring in real time.

[0243] In a particular embodiment, the measurement channel in the ASIC3302 may include a differential PGA followed by a sigma-delta converter. The measurement channel may be calibrated at manufacture with zero input current and a pre-determined current within the accuracy levels described above. The dynamic range of the measurement channel may be set to accommodate the required measurement resolution of glucose in mg / DL. The range of the measurement channel may be determined by one or more factors including glucose measurement range, variation in sensor sensitivity across multiple sensor lots, and temperature sensitivity. The table below illustrates several examples of these factors based on Li. Sensor sensitivity is determined by lot sensor sensitivity in nA / mg / DL and temperature.

[0244] In certain embodiments, bandwidth limiting may be used within the circuit 3300. Bandwidth limiting may be implemented using an external RC filter. In certain embodiments, averaging of the acquired signal may be used to reduce the effect that the substrate may have on the signal provided by the sensor. In certain embodiments, the period used to average the signal may be used. By way of example and not limitation, a period of 16 seconds to average the signal may be used to reduce noise. The sensor 3304 may have a sensor bias similar to the sensor 3202 described herein.

[0245] In a particular embodiment, the ASIC 3302 may have a timer that will time the operation of a state machine that performs the measurement process. The timer may have a threshold accuracy to ensure that the measurement process is completed within a predetermined period of time. The timer may be restarted after the predetermined period of time. By way of example and not limitation, the measurement process may be 50 seconds and the timer may be restarted every minute.

[0246] In a particular embodiment, the ASIC3302 can perform a measurement sequence initiated by the BLE radio over the SPI bus, which can capture glucose channel measurements, temperature measurements, and counter electrode diagnostic measurements.

[0247] In certain embodiments, a reference resistor can be incorporated into circuit 3300 to perform a ratiometric measurement driving a reference current through the thermistor and reference resistor, or the thermistor can provide a sufficiently stable current source such that only a single measurement is required.

[0248] In certain embodiments, the ASIC3302 can implement one or more internal diagnostics including in-band RF detection, counter electrode compliance, and measurement outliers. For in-band RF detection, the diagnostics can provide an indication that NFC was present during the measurement cycle. Data obtained when an electromagnetic field was present can be excluded from on-board glucose calculations. For counter electrode compliance, the diagnostics can detect when the counter electrode control circuit can no longer regulate the REF-CNTR loop. An internal ADC can be used to monitor this voltage. For measurement outliers, the diagnostics can provide an indication that there is a fault in the sensor or sensor connection path. Measurement outliers can be implemented using software that compares four consecutive 8-second measurements (total of 32 seconds) looking for deviations greater than a predefined limit.

[0249] In certain embodiments, the circuit 3300 is discussed in the context of two working electrodes 3310, 3312, but the circuit may utilize one or more working electrodes. As embodied herein, an outlier filter may be incorporated into the digital signal processing module of the ASIC 1830 and may be used to monitor pending measurements before the results are processed. The outlier filter may compare the current result to recent past results (e.g., the most recent result) by comparing pending results to results reported from a previous cycle. If the current result is identified as an outlier (e.g., for deviating from the previous result), the result is removed. As an example, the reported result from a cycle having an outlier may be replaced with the previous result, overwritten with a new measurement, or replaced with a default value indicating that there was an outlier error. The number of outliers recorded over each measurement cycle may be stored and retrieved during processing of the measurements. If a measurement includes a combination of multiple samples, an outlier may be reported for each sample. The digital signal processing module of the ASIC 130 may include an averaging filter that calculates the average of all samples from a single measurement sequence.

[0250] 34 illustrates an example configuration of a circuit 3400 configured to sample signals from a multi-analyte sensor 3412 using multiple ASICs 3404, 3406, 3408. In a particular embodiment, the circuit 3400 can include a microcontroller 3402, ASIC_1 3404, ASIC_2 3406, ASIC_3 3408, a sensor interface 3410, a sensor 3412, an SPI select line_1 3414, an SPI select line_2 3416, an SPI select line_3 3418, and an SPI communication bus 3420. In a particular embodiment, the microcontroller 3402 can interface to the ASICs 3404, 3406, 3408 through the SPI select lines 3414, 3416, 3418 and the SPI communication bus 3420. These ASICs can be coupled to the sensor interface 3410. The sensor interface 3410 can be coupled to the sensor 3412 to receive signals indicative of the level of one or more analytes. In certain embodiments, the sensor 3412 can be embodied as a multi-analyte sensor. In certain embodiments, each of the ASICs 3404, 3406, 3408 can be configured to measure the level of a respective analyte as described herein. The microcontroller 3402 can be configured to control the ASICs 3404, 3406, 3408 to measure the level of a respective analyte. Although FIG. 34 illustrates the circuit 3400 having a predetermined number of components in a particular configuration, the present disclosure contemplates the circuit 3400 having any number of components in a different configuration. By way of example and not limitation, the circuit 3400 can include additional ASICs that measure other analyte signals using the sensor interface 3410 and the sensor 3412.

[0251] In certain embodiments, the temperature detected by the ASIC 1830 or by a temperature sensor associated with the communications module 1840 can be used to adjust the transmitter power of the communications module. In addition to affecting the ability of the signals from the communications module 1840 to be detectable by the receiver 1820, the receiver 1820 can interpret the transmitter power to determine the distance between the sensor 1810 and the receiver 1820. For example, the receiver 1820 can compare the sensed transmit power of the received signal to a specified or expected transmitter power to determine a level or difference of drop to infer the distance between the sensor 1810 and the receiver 1820. The receiver 1820 can provide this information to a user to assist the user in locating the sensor 1810 or the patient to which it is attached. The receiver 1820 can also alert the user that the sensor 1810 is out of range or nearly out of range.

[0252] The communications module 1840 can be configured to disable transmission in response to the temperature failing to meet a threshold temperature. Additionally, the communications module 1840 can be configured to increase or decrease transmitter power in response to the temperature exceeding a predefined interim threshold. For example, the sensor 1810 may have a predefined threshold for maximum power transmission by the communications module. The sensor 1810 may also have a predefined threshold for shutting down the transmitter. An interim transmitter power may be used between these two thresholds. Additionally, the communications module 1840 may incorporate a benchmark value to offset potential hysteresis effects, where a change in transmitter power results in a change in temperature, thereby mitigating potential race conditions. For example, a hysteresis value of 1 degree Celsius may be used as the benchmark.

[0253] In certain embodiments, the background operating current for the multiplexed analyte sensor may be higher than that of the other analyte sensors due to the addition of two dual operational amplifiers. The addition of dual operational amplifiers may add current as much as a predetermined current all the time. The resulting nominal operating current may be another predetermined current that will utilize the battery capacity over a target of a predetermined number of days of operation. The nominal clock frequency output may be frequency1.

[0254] In addition to the specific embodiments claimed below, the subject matter of the present disclosure also relates to other embodiments having any other possible combination of the subordinate features claimed below, as well as those disclosed above and in the accompanying drawings. That is, it should be recognized that the specific features disclosed herein can be combined with each other in other ways within the subject matter of the present disclosure, and thus the subject matter of the present disclosure also specifically relates to other embodiments having any other possible combination. Thus, the above description of specific embodiments of the subject matter of the present disclosure has been provided for purposes of illustration and description. This description is not intended to be exhaustive or to limit the subject matter of the present disclosure to the disclosed embodiments.

[0255] It will be apparent to those skilled in the art that various modifications and variations can be made to the method and system of the presently disclosed subject matter without departing from the spirit or scope of the presently disclosed subject matter, that is, the presently disclosed subject matter is intended to cover such modifications and variations provided they come within the scope of the appended claims and their equivalents. [Explanation of symbols]

[0256] 2800 circuits 2802 Analyte Sensor 2804 First working electrode 2808 Reference electrode 2810 Counter electrode

Claims

1. a multi-analyte sensor including a first working electrode, a second working electrode, a counter electrode, and a reference electrode, each of the first working electrode and the second working electrode configured to receive a signal indicative of the presence of a respective analyte, the counter electrode being a sum of the received signals of each of the first working electrode and the second working electrode; a transimpedance amplifier configured to receive a first one of the received signals from the first working electrode and a second one of the received signals from the second working electrode, the transimpedance amplifier converting the first received signal and the second received signal to an output including a variable bias offset; a differential amplifier configured to subtract the variable bias offset from the output to generate a modified output having a variable residual; a processor configured to generate data indicative of an analyte value from the corrected output; 16. A analyte monitor device comprising:

2. an analog-to-digital converter configured to convert the modified output into a digital output; The device of claim 1 further comprising:

3. The device of claim 2 , wherein the subtraction of the variable bias offset from the output reduces the modified output to within range of the analog-to-digital converter.

4. a communications module configured to process the digital output into a measurement result; The device of claim 2 further comprising:

5. The device of claim 4 , wherein the communication module is further configured to provide the measurement results to a receiving device for display via wireless communication.

6. 13. The device of claim 1 configured to detect blood ketone levels, blood glucose levels, or blood lactate levels.

7. The device of claim 1 , wherein the analyte comprises a ketone.

8. The device of claim 1 , wherein the analyte comprises glucose.

9. The device of claim 1 , wherein the analyte comprises lactate.

10. 10. The device of claim 1, wherein the variable bias offset is determined based on a first analyte measured by the first working electrode or a second analyte measured by the second working electrode.

11. a negatively balanced bias amplifier configured to subtract a predetermined voltage from the reference electrode to generate a first working electrode bias for biasing the first working electrode; The device of claim 1 further comprising:

12. 12. The device of claim 11, wherein the predetermined voltage is determined based on a first analyte measured by the first working electrode or a second analyte measured by the second working electrode.

13. The device of claim 11 , wherein the negatively balanced bias amplifier is configured to receive a reference signal from the reference electrode and a negatively balanced reference value.

14. 2. The device of claim 1, wherein the differential amplifier is further configured to calibrate out bias-dependent residuals and common-mode operational amplifier characteristics from the output to generate the modified output.

15. 15. The device of claim 14, wherein the bias-dependent residual is determined based on a two-point offset calibration for one of the first working electrode or the second working electrode.

16. The device of claim 14 , wherein the common-mode operational amplifier characteristics are determined based on a three-point calibration.

17. the first signal of the received signal is a first current signal; the second signal of the received signals is a second current signal. The device of claim 1 .

18. 20. The device of claim 17, wherein the transimpedance amplifier is further configured to convert the first current signal and the second current signal to an output voltage.

19. 10. The device of claim 1, wherein the processor is further configured to generate the data indicative of the analyte value using a calibration function configured to adjust the generated data based on the variable residual.

20. 10. The device of claim 1, wherein the processor is further configured to generate the data indicative of the analyte value using a calibration function configured to adjust the generated data to remove the variable residuals.

21. a multi-analyte sensor including a first working electrode, a second working electrode, a counter electrode, and a reference electrode, the first working electrode and the second working electrode each configured to receive a signal indicative of the presence of a respective analyte; an application specific integrated circuit configured to receive a first one of the received signals from the first working electrode and a second one of the received signals from the second working electrode, the application specific integrated circuit further configured to set a first independent bias voltage for the first working electrode and a second independent bias voltage for the second working electrode, the application specific integrated circuit further configured to generate data indicative of an analyte using the first independent bias voltage and the second independent bias voltage; 16. A analyte monitor device comprising:

22. 22. The device of claim 21, wherein the application specific integrated circuit is configured to sense one or more signals below a threshold current specific to a particular analyte.

23. a multi-analyte sensor including a first working electrode, a second working electrode, a counter electrode, and a reference electrode, the first working electrode and the second working electrode each configured to receive a signal indicative of the presence of a respective analyte; a first application specific integrated circuit configured to receive a first one of the received signals from the first working electrode, the first application specific integrated circuit setting a first independent bias voltage for the first working electrode, the first application specific integrated circuit further configured to generate data indicative of a first analyte using the first independent bias voltage; a second application specific integrated circuit configured to receive a second one of the received signals from the second working electrode, the second application specific integrated circuit setting a second independent bias voltage for the second working electrode, the second application specific integrated circuit further configured to generate data indicative of a second analyte using the second independent bias voltage; 16. A analyte monitor device comprising:

24. a serial-to-peripheral interface (SPI) interface configured to receive communications from either the first application specific integrated circuit or the second application specific integrated circuit, respectively, the SPI interface including one or more communication lines shared between the first application specific integrated circuit and the second application specific integrated circuit; 24. The device of claim 23, further comprising:

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