Systems and methods for analyte detection

Abstract

To provide apparatus, methods and systems for detecting alcohol concentrations of an individual, such as an in vivo alcohol concentration of an individual.SOLUTION: The blood alcohol concentration can be determined based on the peak signal width of a signal received from an analyte sensor.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The subject matter described herein relates to analyte sensors and methods of use thereof. [Background technology]

[0002] Detection of various analytes can be used to aid in monitoring health conditions. Detection of analytes can be used to determine, among other things, changes in analyte levels that may be indicative of a physiological condition. For example, monitored glucose levels can be used to manage the glucose levels by taking appropriate actions, such as administering insulin at appropriate times or consuming certain foods or beverages, based on the analyte levels or trends. Other analytes may be desirable to monitor other physiological conditions, or in some cases, multiple analytes may be used simultaneously to monitor multiple physiological conditions.

[0003] Analyte monitoring can be performed periodically or continuously over a given period of time. For continuous monitoring, one or more sensors remain at least partially implanted within the individual's tissue (e.g., cutaneously, subcutaneously, or intravenously) so that analysis can be performed in vivo. The implanted sensors can collect analyte data on demand, on a set schedule, or continuously, depending on the individual's particular health needs and / or previously measured analyte levels. For example, in vivo enzyme-based amperometric sensors can be configured to assay one or more analytes and monitor the health of an individual. Analyte sensors may use enzymes that have specificity or sensitivity for a particular substrate. Analytes monitored can include, but are not limited to, glucose, lactate, oxygen, and ketones, for example.

[0004] By comparison, but not by way of limitation, periodic analyte monitoring can be performed by taking a sample of a bodily fluid, such as blood or urine, and analyzing the sample ex vivo. Although ex vivo analyte monitoring can be sufficient, there are several challenges associated with ex vivo analyte monitoring. For example, taking a sample can be inconvenient or painful, and there can be an increased risk of losing data. Continuous analyte monitoring, including such monitoring using sensors implanted in vivo, can overcome such challenges.

[0005] Another example of an analyte that can be monitored is alcohol. Information about an individual's in vivo alcohol level can be used, for example, to predict or monitor the level of another analyte of interest. For example, alcohol can alter glycemic control in individuals whose glucose levels are naturally dysregulated or otherwise lack homeostasis without intervention. Other analytes that can be dysregulated by alcohol can include triglycerides (e.g., associated with heart disease, stroke, blood pressure, obesity), gamma-glutamyltransferase (GGT) (e.g., associated with cancer, hepatitis, bone disease), and cortisol (e.g., associated with stress, inflammation). Alcohol monitoring can also be used, for example, to curb alcohol consumption. Thus, it can be useful to continuously or periodically monitor an individual's alcohol level. Summary of the Invention

[0006] The objects and advantages of the disclosed subject matter will be set forth in and apparent from the following description and will be learned by practice of the disclosed subject matter. Additional advantages of the disclosed subject matter will be realized and attained by the devices particularly pointed out in the written description and claims hereof, as well as from the appended drawings.

[0007] To achieve these and other advantages, and in accordance with the purpose of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter is directed to an apparatus that may be communicatively connected to an alcohol sensor, a system that may include an alcohol sensor, or a method that may include receiving data or a signal from an alcohol sensor. For example, the apparatus may include one or more processors. The one or more processors may be configured to receive a signal from an analyte sensor. The analyte sensor may be, for example, an alcohol sensor. At least a portion of the analyte sensor is disposed in contact with a bodily fluid. The one or more processors are also configured to determine a peak signal width of a signal received from the analyte sensor over a period of time. Additionally, the one or more processors are configured to determine a blood alcohol concentration based in part on the peak signal width of the received signal.

[0008] As embodied herein, a method may include receiving a signal from an analyte sensor disposed at least in part in contact with a bodily fluid. The method may also include determining a peak signal width of the signal received from the analyte sensor over a period of time. Further, the method may include determining a blood alcohol concentration based in part on the peak signal width of the signal.

[0009] As embodied herein, the period over which the width of the peak signal is determined may be an initial wear period of the analyte sensor, for example, 1, 2, 3, 4, or 5 days after insertion of the analyte sensor.

[0010] As embodied herein, the one or more processors may be configured to determine a blood alcohol concentration based on a ratio of the amplitude of the peak signal to the width of the peak signal. As embodied herein, the one or more processors may be configured to determine the blood alcohol concentration based on a sensitivity of the alcohol sensor, which may be set at the factory based on a calibration.

[0011] As embodied herein, an analyte sensor includes one or more active areas. The active areas may include one or more enzymes, which degrade over the life of the alcohol sensor. In some examples, the one or more active areas of the analyte sensor detect two or more analytes. The two or more analytes may include ethanol, glucose, or lactate.

[0012] As embodied herein, the one or more processors may display the blood alcohol concentration on the device that is the reader device. In some examples, the one or more processors may include outputting a visual, audio, or vibratory alert based on the blood alcohol concentration. [Brief description of the drawings]

[0013] [Figure 1A] 1 is a system overview of a sensor applicator, a reader device, a monitoring system, a network, and a remote system. [Figure 1B] FIG. 1 illustrates an operating environment for an exemplary analyte monitoring system for use with the technology described herein. [Figure 2A] FIG. 2 is a block diagram illustrating an example embodiment of a reader device. [Figure 2B] 1 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] Same as above. [Figure 2E] 1 is a block diagram illustrating an exemplary analyte sensor in accordance with an exemplary embodiment of the disclosed subject matter. [Figure 3A] FIG. 13 is a proximal perspective view showing an exemplary embodiment in which a user prepares a tray for assembly. [Figure 3B] 1A-1C are side views illustrating an exemplary embodiment in which a user prepares the applicator device for assembly. [Figure 3C]13A-13C are proximal perspective views illustrating an exemplary embodiment in which a user inserts an applicator device into a tray during assembly. [Figure 3D] 13A-13C are proximal perspective views illustrating an exemplary embodiment in which a user removes the applicator device from a tray during assembly. [Figure 3E] 1 is a proximal perspective view illustrating an exemplary embodiment of a patient applying a sensor using an applicator device. [Figure 3F] 1A-1C are proximal perspective views illustrating an exemplary embodiment of a patient with a sensor applied and a used applicator device. [Figure 4A] 1A and 1B are side views illustrating an exemplary embodiment of an applicator device coupled with a cap. [Figure 4B] 1A-1C are side perspective views illustrating an exemplary embodiment of an applicator device and cap separated. [Figure 4C] 1 is a perspective view illustrating an exemplary embodiment of a distal end of an applicator device and an electronics housing. [Figure 4D] 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 proximal perspective view of an exemplary embodiment of a tray with a sterilization lid attached thereto. [Figure 6A] FIG. 13 is a proximal perspective cutaway view showing an exemplary embodiment of a tray with sensor delivery components. [Figure 6B] FIG. 13 is a proximal perspective view showing the sensor delivery components. [Figure 7A] FIG. 2 is an isometric exploded top view of an exemplary sensor control device. [Figure 7B] FIG. 2 is an isometric exploded bottom view of an exemplary sensor control device. [Figure 8A]8A-8C are assembly and cross-sectional views of an on-body device including an integrated connector for a sensor assembly. [Figure 8B] Same as above. [Figure 8C] Same as above. [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] 11A-11C are progressive cross-sectional side views illustrating the assembly of a sensor applicator with the sensor control device of FIGS. 10A-10B. [Figure 11B] Same as above. [Figure 11C] Same as above. [Figure 12A] 12A-12C are progressive cross-sectional side views illustrating assembly and disassembly of an exemplary embodiment of a sensor applicator with the sensor control device of FIGS. 10A-10B. [Figure 12B] Same as above. [Figure 12C] Same as above. [Figure 13A] 1A-1C show cross-sectional views illustrating an exemplary embodiment of an applicator during a deployment stage. [Figure 13B] Same as above. [Figure 13C] Same as above. [Figure 13D] Same as above. [Figure 13E] Same as above. [Figure 13F] Same as above. [Figure 14] 1 is a graph showing an example of the in vitro sensitivity of an analyte sensor. [Figure 15] 1A-1D illustrate example operational states of a sensor in accordance with an example embodiment of the disclosed subject matter. [Figure 16]FIG. 1 illustrates an example operation and data flow for wireless programming of a sensor in accordance with the disclosed subject matter. [Figure 17] 1 illustrates an example data flow for reliable exchange of data between two devices in accordance with the disclosed subject matter. [Figure 18A] FIG. 1 illustrates a cross-sectional view of an exemplary analyte sensor including a single active area as embodied herein. [Figure 18B] Same as above. [Figure 18C] Same as above. [Figure 19] FIG. 1 illustrates a cross-sectional view of an exemplary analyte sensor including two active areas as embodied herein. [Figure 20] FIG. 1 illustrates a cross-sectional view of an exemplary analyte sensor including two active areas as embodied herein. [Figure 21A] 1 is a graph illustrating the current output of an exemplary analyte sensor embodied herein. [Figure 21B] Same as above. [Figure 22] 1 is a graph illustrating the current output of an exemplary analyte sensor embodied herein. [Figure 23] 1 is a graph illustrating the current output of an exemplary analyte sensor embodied herein. [Figure 24] 1 is a graph illustrating the current output of an exemplary analyte sensor embodied herein. [Diagram 25] FIG. 25 illustrates the correlation between blood alcohol concentration (BAC) measured at the signal peak and the width of the corresponding current peak using the exemplary analyte sensor of FIG. 24. [Figure 26] FIG. 25 illustrates the correlation between total alcohol consumption (BAC) measured at the signal peak and the width of the corresponding current peak using the exemplary analyte sensor of FIG. 24. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Before describing the present subject matter in detail, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is also 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 present disclosure will be limited only by the appended claims.

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

[0016] Publications 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 publication by virtue of prior disclosure. Further, the dates of publication 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 monitoring system. The applicator can be provided to a user in a sterile package containing the electronics housing of the sensor control device. According to some embodiments, a structure separate from the applicator, such as a container, can also be provided to a user as a sterile package containing a sensor module and a sharps module. A user can couple the sensor module to the electronics housing and can 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 may be provided in a single package. The applicator may be used to place 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 to reduce the likelihood that the sensor will be improperly inserted or damaged, or induce an adverse physiological response. Other improvements and advantages are provided as well. Various configurations of these devices are described in detail by way of embodiments that are merely examples.

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

[0019] Furthermore, for any and all embodiments of the methods disclosed herein, systems and devices capable of performing each of those embodiments are encompassed within the scope of the present disclosure. For example, sensor control device embodiments are disclosed, but these devices may have one or more sensors, analyte monitoring 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), which may perform or facilitate the performance of any and all method steps. These sensor control device embodiments may be used or may be capable of being used to implement steps performed by the sensor control device from any and all of the methods described herein.

[0020] Additionally, the systems and methods presented herein may be used for the operation of sensors used in analyte monitoring systems, such as, but not limited to, wellness, fitness, diet, research, information, or any purpose related to analyte sensing over time. As used herein, an "analyte sensor" or "sensor" may refer to any device capable of receiving 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 physical movement sensor, or any other sensor for collecting physical or biological information. Analytes measured by an analyte sensor may include, by way of example and not limitation, 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, several embodiments of systems, devices, and methods are described herein that provide improved assembly and use of skin sensor insertion devices for use with in vivo analyte monitoring systems. In particular, several embodiments of the present disclosure are designed to improve the method of sensor insertion with respect to in vivo analyte monitoring systems, and in particular to prevent premature retraction of the insertion sharp during the sensor insertion process. Some embodiments include a skin sensor insertion mechanism that, for example, increases the firing rate and slows the retraction of the sharp. In other embodiments, the sharp retraction mechanism may be motion actuated such that the sharp is not retracted until the user pulls the applicator away from the skin. As a result, these embodiments can reduce the possibility of premature withdrawal of the insertion sharp during the sensor insertion process, reduce the possibility of improper sensor insertion, and reduce the possibility of damaging the sensor during the sensor insertion process, to name a few advantages. Some embodiments of the present disclosure also provide an improved insertion sharps module that takes into account the small-scale skin sensors and the relatively shallow insertion path present in the dermis layer of a subject. In addition, 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 therefore reduce the likelihood of capillary breakage resulting in instability of the placed skin 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 needle end penetration depth relative to the sensor tip during insertion.

[0022] However, before describing these aspects of the embodiments in detail, it is desirable to first describe examples of devices that may be present, for example, in an in vivo analyte monitoring system, as well as examples of their operation, all of which may be used in conjunction with the embodiments described herein.

[0023] There are various types of in vivo analyte monitoring systems. A "continuous analyte monitoring" system (or a "continuous glucose monitoring" system) may, for example, transmit data from a sensor control device to a reader device continuously and without prompting, e.g., automatically according to a schedule. As another example, a "flash analyte monitoring" system (or a "flash glucose monitoring" system or simply a "flash" system) may transfer data from a sensor control device in response to a scan or request for data by a reader device, such as using near field communication (NFC) or radio frequency identification (RFID) protocols. An in vivo analyte monitoring system may also operate without the need for finger-prick calibration.

[0024] In vivo analyte monitoring systems can be distinguished from "in vitro" systems, which contact a biological sample outside the body (or "ex vivo") and typically include a measurement device having a port for accepting an analyte test strip that carries a user's bodily fluid that can 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 disposed in vivo and senses analyte levels contained therein. The sensor may be part of a sensor control device that resides on the user's body and contains electronics and a power source that enable and control analyte sensing. Sensor control devices and variations thereof may also be referred to as "sensor control units," "on-body electronics" devices or units, "on-body" devices or units, or "sensor data communication" devices or units, to name a few.

[0026] The in-vivo monitoring system may also include a device that receives the sensed analyte data from the sensor control device and processes and / or displays the sensed analyte data 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 utilized with or incorporated into in-vivo and in-vitro monitoring systems.

[0027] FIG. 1A is a conceptual diagram illustrating an exemplary embodiment of an analyte monitoring system 100 including a sensor applicator 150, a sensor control device 102, and a reader device 120. Here, 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 analyte sensor 110 is maintained in place for a period of time by an adhesive patch 105. The sensor control device 102 is further described in FIGS. 2B and 2C and can communicate with the reader device 120 via a communication path 140 using wired or wireless technology. Exemplary wireless protocols include Bluetooth, Bluetooth Low Energy (BLE, BTLE, Bluetooth SMART, etc.), Near Field Communication (NFC), etc. A user can monitor applications installed in memory on the reader device 120 using the screen 122 and input 121, and the device battery can be recharged using a power port 123. Further details about the reader device 120 are described with respect to FIG. 2A below. The reader device 120 can communicate with the local computer system 170 over communication path 141 using wired or wireless technology. The local computer system 170 may include one or more of a laptop, desktop, tablet, phablet, smartphone, set-top box, video game console, or other computing device, and the wireless communication may 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 over communication path 143 by the aforementioned wired or wireless technology, similar to how the reader device 120 can communicate with the network 190 over communication path 142. The network 190 can be any of several networks, such as private and public networks, local area networks, 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 via communication path 144 by wired or wireless technology.

[0028] FIG. 1B illustrates an operating environment for an analyte monitoring system 100a that can embody the technology described herein. The analyte monitoring system 100a may include a system of components designed to provide monitoring of parameters such as analyte levels of a human or animal body, or may provide other operations based on the configuration of various components. As embodied herein, the system may include a low-power analyte sensor 110, or simply a "sensor," that is 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., 1 day, 14 days, 30 days, etc.). The sensor 110 may be applied to the skin of the user's body and remain attached for the duration of the sensor life, or may be designed to remain functional when selectively removed and reapplied. The low power analyte monitoring 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 delivery 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 via a remote application server 150 or an application storefront server 160, and embedded in a general-purpose hardware device 130, such as a mobile phone, tablet, personal computing device, or other similar computing device, that may communicate with the analyte sensor 110 via a communication link. The general-purpose hardware may further include embedded devices, including but not limited to an insulin pump or insulin pen, having embedded libraries configured to communicate with the analyte sensor 110. While 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 incorporates multiple respective components that interact throughout the system. For example, but not limited to, as embodied herein, the data reading device 120 and / or the general-purpose data receiving device 130 may include multiple respective. As embodied herein, the multiple data receiving devices 130 may communicate directly with the sensor 110 as described herein. Additionally or alternatively, the data receiving device 130 may communicate with a secondary data receiving device 130 to provide the analyte data, or visualization or analysis of the data, for secondary display to a user or other authorized party.

[0030] 2A is a block diagram illustrating an example embodiment of a reader device configured as a smartphone, where 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. A separate memory 230, an RF transceiver 228 having an antenna 229, and a power source 226 having a power management module 238 may also be included. It may further include a multi-function transceiver 232 capable of communicating via Wi-Fi, NFC, Bluetooth, BTLE, and GPS via an antenna 234. 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 for use with the disclosed subject matter as shown in FIG. 2B. The data receiving device 120 and associated general-purpose data receiving device 130 include components germane to the description 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 made by the same manufacturer as the sensor 110.

[0032] 2B, the data receiving device 120 includes an ASIC 4000 that includes a microcontroller 4010, a memory 4020, and a storage 4030, and is 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 (e.g., 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 interface with the analyte sensor 110, send commands to the analyte sensor 110, 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 via 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 as described herein. For example, the data receiving device 120 may use a first module of the communication module 4040 to issue commands (e.g., an activation command for a data broadcast mode of the sensor, a pairing command to identify the data receiving device 120) to the analyte sensor 110, and may use a second module of the communication module 4040 to receive data from and send data to the analyte sensor 110. The data receiving device 120 may be configured to communicate with the user device 140 via 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 using broadband cellular networks, 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 using wireless local area networks according to one or more of the IEEE 802.11 standards (e.g., 802.11a, 802.11b, 802.11g, 802.11n (also known as Wi-Fi 4), 802.11ac (also known as Wi-Fi 5), 802.11ax (also known as Wi-Fi 6)). Using the cellular radio module 4044 or the Wi-Fi radio module 4043, the data receiving device 120 may 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 shown, the communication module 5040 of the analyte sensor 120 may similarly include a cellular radio module or a Wi-Fi radio module.

[0035] As embodied herein, the on-board storage 4030 of the data receiving device 120 may 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 may be configured to communicate with a remote application server 150 over a wide area network. As embodied herein, the analyte sensor 110 may provide data to the data receiving device 120 or the general-purpose data receiving device 130. The data receiving device 120 may transmit the data to the user computing device 140. The user computing device 140 (or the general-purpose data receiving device 130) may then transmit the 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 in conjunction with the analyte sensor 110 to operate based on the analyte data received from the analyte sensor 110. As an example, if the analyte sensor 110 is a glucose sensor, the data receiving device 120 may be or include an insulin pump or insulin injection pen. In conjunction, the compatible device 130 may adjust an insulin dose for 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 (including analyte monitoring circuitry) that may have most of the processing power for rendering final result data suitable for display to a user. In FIG. 2C, a single semiconductor chip 161 is shown, which may be a custom application specific integrated circuit (ASIC). Shown within the ASIC 161 are certain high level functional units 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 implemented as a transmitter, receiver, transceiver, passive circuitry, or otherwise following a communication protocol). In this embodiment, both the AFE 162 and the processor 166 are used as analyte monitoring circuitry, although in other embodiments, either circuitry may perform the analyte monitoring function. The processor 166 may include one or more processors, microprocessors, controllers, and / or microcontrollers, each of which may be a separate chip or may be distributed among (and portions of) several different chips.

[0038] The memory 163 is also included in the ASIC 161 and may be shared by the various functional units present in the ASIC 161 or distributed among two or more of them. 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 interacts with the in-vivo analyte sensor 110, receives measurement data therefrom, and outputs the data in digital form to the processor 166, which then processes the data to arrive at final result glucose discrete values ​​and trend values, etc. This data may then be provided to the communication circuitry 168 for transmission via the antenna 171 to the reader device 120 (not shown), where, for example, minimal further processing is required by a resident software application to display the data.

[0039] FIG. 2D is similar to FIG. 2C, but instead includes two separate semiconductor chips 162 and 174, which may be packaged together or separately. Here, AFE 162 resides on ASIC 161. Processor 166 is integrated with power management circuitry 164 and communication circuitry 168 on chip 174. AFE 162 includes memory 163, and chip 174 includes memory 165, which may be separated or distributed within. In one exemplary embodiment, AFE 162 is combined with power management circuitry 164 and processor 166 on one chip, and communication circuitry 168 is on a separate chip. In another exemplary embodiment, both AFE 162 and communication circuitry 168 are on one chip, and processor 166 and power management circuitry 164 are on another chip. It should be noted that other chip combinations are possible, including three or more chips, with each chip performing separate functions as described, or sharing one or more functions for 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 disclosed subject matter as shown in Figure 2E, which illustrates a block diagram of an exemplary analyte sensor 110 according to an exemplary embodiment that is compatible with the security architecture and communication schemes described herein.

[0041] As embodied herein, the analyte sensor 110 may include an application specific integrated circuit ("ASIC") 5000 communicatively coupled to a communication module 5040. The ASIC 5000 may include a microcontroller core 5010, an on-board memory 5020, and a storage memory 5030. The storage memory 5030 may store data used in the authentication and encryption security architecture. The storage memory 5030 may store programming instructions for the sensor 110. As embodied herein, a specific communication chipset may be incorporated into the ASIC 5000 (e.g., NFC transceiver 5025). The ASIC 5000 may 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 may be programmed to include information such as an identifier of the sensor 110 for identification and tracking purposes. The storage memory 5030 may also be programmed with configuration or calibration parameters for use by the sensor 110 and its various components. The storage memory 5030 may include rewriteable 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 of 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. As used throughout this disclosure, Bluetooth Low Energy ("BLE") refers to a short-range communication protocol optimized to make Bluetooth device pairing simple for end users. The communication module 5040 may transmit and receive data and commands via interaction with a similarly capable communication module of 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 personal area networks according to the IEEE 802.15 protocol, IEEE 802.11 protocol, infrared communication according to the Infrared Data Association standard (IrDA), and the like.

[0043] To perform its functions, the sensor 100 may further include appropriate sensing hardware 5060 appropriate for that function. As embodied herein, the sensing hardware 5060 may include an analyte sensor disposed 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 in the bodily fluid.

[0044] The components of the sensor control device 102 may be obtained by the user in multiple packages that require final assembly by the user prior to delivery to the appropriate user location. Figures 3A-3D show an exemplary embodiment of an assembly process for the sensor control device 102 by the user, including preparation of the separate components prior to combining the components to prepare the sensor for delivery. Figures 3E-3F show an exemplary embodiment of delivery of the sensor control device 102 to an appropriate user location by selecting an appropriate delivery location and applying the device 102 to that location.

[0045] 3A is a proximal perspective view showing an exemplary embodiment in which a user prepares a container 810, here configured as a tray (although other packaging may be used), for an assembly process. The user may accomplish this preparation by removing the lid 812 from the tray 810 to expose the platform 808, for example, by peeling a 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 may be appropriate in various embodiments so long as the platform 808 is properly exposed within the tray 810. The lid 812 may then be set aside.

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

[0047] 3C is a proximal perspective view showing an exemplary embodiment in which a user inserts applicator device 150 into tray 810 during assembly. First, a user may align housing orientation portion 1302 (or slot or recess) and tray orientation portion 924 (abutment or detent) and then insert sheath 704 into inner platform 808 of tray 810. Inserting sheath 704 into platform 808 temporarily unlocks sheath 704 relative to housing 702 and platform 808 relative to tray 810. Removal of applicator device 150 from tray 810 at this stage will result in the same condition as before initial insertion of applicator device 150 into tray 810 (i.e., the process can be reversed or interrupted at this point and then repeated without incident).

[0048] The sheath 704 may maintain its position within the platform 808 relative to the housing 702 while the housing 702 is advanced distally, thereby mating with the platform 808 and advancing the platform 808 distally relative to the tray 810. This step unlocks the platform 808 and folds it into the tray 810. The sheath 704 may contact and disengage a locking portion (not shown) within the tray 810 that unlocks the sheath 704 relative to the housing 702 and prevents the sheath 704 from moving (relatively) while the housing 702 continues to advance the platform 808 distally. At the end of the advancement of the housing 702 and platform 808, the sheath 704 is permanently unlocked relative to the housing 702. The sharps and sensors (not shown) within the tray 810 may be mated with the electronics housing (not shown) within the housing 702 at the end of the distal advancement of the housing 702. The operation and interaction of applicator device 150 and tray 810 are further described below.

[0049] 3D is a proximal perspective view showing 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 motion that has the same end effect of separating applicator 150 and tray 810. Applicator device 150 is removed with sensor control device 102 (not shown) fully assembled therein (sharps, sensor, electronics) and positioned for delivery.

[0050] 3E is a proximal perspective view showing an exemplary embodiment of a patient using applicator device 150 to apply sensor control device 102 to a target area of ​​skin, e.g., the abdomen or other suitable location. Distal advancement of housing 702 causes sheath 704 to collapse within housing 702, and the sensor is applied to the target location such that the adhesive layer on the bottom side of sensor control device 102 adheres to the skin. The sharp is automatically retracted when housing 702 is fully advanced, but the sensor (not shown) is left in place to measure the analyte level.

[0051] 3F is a proximal perspective view showing an exemplary embodiment of a patient with the sensor control device in place. The user can then remove the applicator 150 from the application site.

[0052] The system 100 described with respect to Figures 3A-3F and elsewhere herein can reduce or eliminate the possibility of accidental breakage, permanent deformation, or incorrect assembly of applicator components 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 via the sheath 704, the relative angle between the sheath 704 and the housing 702 does not result in breakage or permanent deformation of the arms or other components. The possibility of relatively large forces (as in conventional devices) during assembly is reduced, which in turn reduces the possibility of failed assembly by the user.

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

[0054] 4D-G, for purposes of illustration and not limitation, the applicator device 20150 may be provided to a user as a single integrated 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. The perspective views show how the applicator 20150 is shipped to and received by a user. The exploded and cutaway views show the components of the applicator device 20150. The applicator device 20150 may include a housing 20702, a gasket 20701, a sheath 20704, a sharps carrier 201102, a spring 205612, a sensor carrier 20710 (also referred to as a "puck carrier"), a sharps 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 a tamper evidence portion 20712. When received by a user, only the housing 20702, the cap 20708, the tamper evidence portion 20712, and the label 20709 are visible. The tamper evidence portion 20712 may be, for example, a sticker coupled to each of the housing 20702 and the cap 20708, and the tamper evidence portion 20712 may be, for example, irreparably damaged by separating the housing 20702 and the cap 20708, thereby indicating to a user that the housing 20702 and the cap 20708 have previously been separated. These features are described in more detail below.

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

[0056] 6A is a proximal perspective cutaway view showing the sensor delivery components within a tray 810. A platform 808 is slidably coupled within the tray 810. A desiccant 502 is stationary relative to the tray 810. A sensor module 504 is mounted within the tray 810.

[0057] 6B is a proximal perspective view showing 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 sharps module 2500, and the sensor (not shown) so that they can be removed together as the sensor module 504 during assembly.

[0058] With brief reference again to FIG. 1 and FIG. 3A-3G, in the case of 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 open each package and ultimately assemble the system. In some applications, the 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 the others. More specifically, the sensor tray 202 including the plug assembly 207 including the sensor 110 and the sharps 220 may be sterilized using radiation sterilization, such as electron beam (or "e-beam") irradiation. Suitable radiation sterilization processes include, but are not limited to, electron beam (e-beam) irradiation, gamma irradiation, x-ray irradiation, or any combination thereof. However, radiation sterilization may damage electrical components disposed 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 may be sterilized by another method, such as gas chemical sterilization using, for example, ethylene oxide. However, gas chemical sterilization may damage enzymes or other chemicals and biologics 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, which requires final assembly of the components for use by the user.

[0059] 7A and 7B are isometric exploded top and bottom views, respectively, of a sensor control device 3702 according to one or more embodiments. The shell 3706 and the mount 3708 operate 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 may include a printed circuit board assembly (PCBA) 3802 including a printed circuit board (PCB) 3804 to which a number of electronic modules 3806 are coupled. 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 may 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 also include a data processing unit 3808 mounted on the PCB 3804. The data processing unit 3808 may comprise, for example, an application specific integrated circuit (ASIC) configured to implement one or more functions or routines associated with the operation of the sensor control device 3702. More specifically, the data processing unit 3808 may be configured to perform data processing functions, such functions may include, but are not limited to, filtering and encoding data signals each corresponding to a sampled user's analyte level. The data processing unit 3808 may also include an antenna for communicating with or otherwise communicating with the reader device 106 (FIG. 1).

[0061] The battery opening 3810 may be defined in the PCB 3804 and sized to receive and mount a battery 3812 configured to power the sensor control device 3702. The axial battery contact 3814a and the radial battery contact 3814b may be coupled to the PCB 3804 and extend into the battery opening 3810 to facilitate the transfer of power from the battery 3812 to the PCB 3804. As their names suggest, the axial battery contact 3814a may be configured to provide an axial contact for the battery 3812, while the radial battery contact 3814b may provide a radial contact for the battery 3812. Locating the battery 3812 in the battery opening 3810 with the battery contacts 3814a,b helps to reduce the height H of the sensor control device 3702, which allows the PCB 3804 to be centrally located and its components distributed on both sides (i.e., top and bottom). This also helps facilitate the chamfer 3718 provided on the electronics housing 3704 .

[0062] The sensor 3716 may be centrally disposed with respect to the PCB 3804 and may include a tail 3816, a flag 3818, and a neck 3820 interconnecting 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 transdermally received beneath the skin of a user. Additionally, the tail 3816 may have an enzyme or other chemical 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) disposed thereon. The sensor contacts 3822 may be configured to align and engage with corresponding one or more 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 silicone rubber connector that encapsulates one or more compliant carbon-impregnated polymer modules that function 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 connection, which eliminates the need for a prior art connector and advantageously reduces the height H. Additionally, by eliminating the compliant 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 disposed 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 continuously engages the sensor contacts 3822 with corresponding circuit contacts 3824. In the illustrated embodiment, the compliant member 3826 is an elastomeric O-ring, but may alternatively comprise any other type of biasing device or mechanism, such as a compression spring, 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 define a first clocking receptacle 3830a (FIG. 7B) and a second clocking receptacle 3830b (FIG. 7B), and the mount 3708 may provide or 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,b with the first and second clocking posts 3832a,b, respectively.

[0066] 7A , the inner surface of the mount 3708 may provide or define a number of pockets or recesses configured to accommodate various components 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 may define a battery locator 3834 configured to accommodate a portion of the battery 3812 when the sensor control device 3702 is assembled. An adjacent contact pocket 3836 may be configured to accommodate a portion of the axial contact 3814a.

[0067] Additionally, a plurality of module pockets 3838 may be defined on the inner surface of the mount 3708 to accommodate various electronic modules 3806 disposed on the bottom of the PCB 3804. Additionally, a shield locator 3840 may be defined on the inner surface of the mount 3708 to accommodate 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 inner surface of the mount 3708, such that the overall height H of the sensor control device 3702 may be reduced compared to conventional sensor control devices. The module pockets 3838 may also help minimize the diameter of the PCB 3804 by allowing PCB components to be disposed on both sides (i.e., the top and bottom).

[0068] 7A, the mount 3708 may further include a plurality of carrier grip portions 3842 (two are shown) defined around the circumference of the mount 3708. The carrier grip portions 3842 are axially offset from a bottom 3844 of the mount 3708 to allow a transfer adhesive (not shown) to be applied to the bottom of the mount during assembly. In contrast to conventional sensor control devices that typically include a conical carrier grip portion that intersects with the bottom of the mount, the carrier grip portions 3842 of the present disclosure are offset from the plane where the transfer adhesive is applied (i.e., the bottom 3844). This proves to be advantageous in helping to ensure that the delivery system does not inadvertently stick to the transfer adhesive during assembly. Additionally, the carrier grip portions 3842 of the present disclosure eliminate the need for a corrugated transfer adhesive, which simplifies the manufacture of the transfer adhesive as well as eliminates the need to precisely clock the transfer adhesive against the mount 3708. This also increases the bond area and therefore the bond strength.

[0069] With reference to FIG. 7B, the bottom 3844 of the mount 3708 may provide or otherwise define a number of grooves 3846, which 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 coupled to the bottom 3844, and the grooves 3846 may be configured to help wick (transfer) moisture away from the sensor control device 3702 toward the periphery of the mount 3708 during use. In some embodiments, the spacing of the grooves 3846 may sandwich a module pocket 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 pocket 3838 ensures that opposing features on either side of the mount 3708 do not extend into one another. This helps to maximize the use of material for the mount 3708, which may help to maintain a minimum height H of the sensor control device 3702. The module pocket 3838 can also significantly reduce mold sink and improve the flatness of the bottom 3844 where the transfer adhesive bonds.

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

[0071] A sharps and sensor locator 3852 may also be provided by or otherwise defined on an inner surface of the shell 3706. The sharps and sensor locator 3852 may be configured to receive both a sharp (not shown) and a portion of the sensor 3716. Additionally, the sharps and sensor locator 3852 may be configured to align and / or mate with a corresponding sharps and sensor locator 2054 ( FIG. 7A ) provided on an inner surface of the mount 3708.

[0072] According to an embodiment of the present disclosure, an alternative sensor assembly / electronics assembly connection approach is shown in Figures 8A-8C. As shown, the sensor assembly 14702 includes a sensor 14704, a connector support 14706, and a sharp 14708. In particular, a recess or receptacle 14710 may be defined in the bottom of the mount of the electronics assembly 14712, providing a location where the sensor assembly 14702 may be received and coupled to the electronics assembly 14712, thereby allowing the sensor control device to be fully assembled. The contours of the sensor assembly 14702 may be complementarily fitted or molded to the receptacle 14710, which includes an elastomeric sealing member 14714 (which includes a conductive material coupled to the circuit board and aligned with the electrical contacts of the sensor 14704). Thus, by driving the sensor assembly 14702 into a recess 14710 integrally formed in the electronics assembly 14712, when the sensor assembly 14702 is snap-fit ​​or otherwise adhered to the electronics assembly 14712, the on-body device 14714 shown in FIG. 8C is formed. This embodiment provides an integrated connector for the sensor assembly 14702 in the electronics assembly 14712.

[0073] Further information regarding sensor assemblies is provided in U.S. Patent Application Publication No. 2013 / 0150691 and U.S. Patent Application Publication No. 2021 / 0204841, each of which is incorporated by reference in its entirety into this specification.

[0074] According to an embodiment of the present disclosure, the sensor control device 102 may be modified to provide a one-piece architecture that can undergo 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. Rather, the user only needs to open one package and then deliver the sensor control device 102 to the target monitoring location. The one-piece system architecture described herein may prove advantageous in eliminating components, various fabrication process steps, and user assembly steps. As a result, packaging and waste are reduced, as well as the possibility of user error or contamination of the system is mitigated.

[0075] 9A and 9B are a side view and a cross-sectional side view, respectively, of an exemplary embodiment of the sensor applicator 102 having an applicator cap 210 coupled thereto. More specifically, FIG. 9A illustrates how the sensor applicator 102 is shipped to and received by a user, and FIG. 9B illustrates the sensor control device 4402 disposed within the sensor applicator 102. Thus, a fully assembled sensor control device 4402 may already be assembled and installed within the sensor applicator 102 before being delivered to the user, thus eliminating any additional assembly steps that the user would otherwise have to perform.

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

[0077] According to the present disclosure, while loaded into the sensor applicator 102, the sensor control device 4402 may be subjected to a gaseous chemical sterilization 4704 configured to sterilize the electronics housing 4404 and any other exposed portions of the sensor control device 4402. To accomplish this, a chemical may be injected into a sterilization chamber 4706 cooperatively defined by the sensor applicator 102 and the interconnected cap 210. In some applications, the chemical may be injected into the sterilization chamber 4706 via one or more vents 4708 defined in the proximal end 610 of the applicator cap 210. Exemplary chemicals that may be used for gaseous chemical sterilization 4704 include, but are not limited to, ethylene oxide, vaporized hydrogen peroxide, nitrogen oxides (e.g., nitrous oxide, nitrogen dioxide, etc.), and steam.

[0078] Because the sensor 4410 and the distal portion of the sharps 4412 are sealed within the sensor cap 4416, the chemicals used during the gas chemical sterilization process do not interact with the enzymes, chemicals, and biologics provided on the tail 4524 and other sensor components such as the membrane coating that regulates analyte influx.

[0079] Once the desired sterility assurance level has been achieved within the sterilization chamber 4706, the gaseous solution may be removed and the sterilization chamber 4706 may be vented. Venting may be accomplished by a series of vacuum pulls followed by circulating a gas (e.g., nitrogen) or filtered air through the sterilization chamber 4706. Once the sterilization chamber 4706 has been properly vented, the vent port 4708 may be blocked with a seal 4712 (shown in dashed lines).

[0080] In some embodiments, the seal 4712 may comprise two or more layers of different materials. The first layer may be made of a synthetic material (e.g., flash-spun high density polyethylene fibers) such as Tyvek® available from DuPont®. Tyvek® is highly durable and 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 vapor and moisture resistant material layer may be sealed (e.g., heat sealed) over the Tyvek® layer to prevent ingress of contaminants and moisture into the sterilization chamber 4706. In other embodiments, the seal 4712 may comprise only a single protective layer applied to the applicator cap 210. In such embodiments, the single layer may be gas permeable for the sterilization process, but may also be capable of protecting against moisture and other harmful elements once the sterilization process is complete.

[0081] With the seal 4712 in place, the applicator cap 210 provides a barrier to outside 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 may also create a dust-free environment during shipping and storage that prevents the adhesive patch 4714 from becoming soiled.

[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 best understood by referring to FIG. 1. Additionally, the sensor control device 5002 may replace the sensor control device 102 of FIG. 1 and thus may be used with the sensor applicator 102 of FIG. 1 that can deliver the sensor control device 5002 to a target monitoring location on the skin of a user.

[0083] However, unlike the sensor control device 102 of FIG. 1, the sensor control device 5002 may comprise a one-piece system architecture that does not require a user to open multiple packages and ultimately assemble the sensor control device 5002 prior to application. Rather, upon receipt by a user, the sensor control device 5002 may already be fully assembled and properly positioned within the sensor applicator 150 (FIG. 1). To use the sensor control device 5002, the user only needs to open one barrier (e.g., applicator cap 708 of FIG. 3B) before quickly delivering the sensor control device 5002 to a target monitoring location for use.

[0084] As shown, the sensor control device 5002 includes an electronics housing 5004 that is generally disk-shaped and may have a circular cross-section. However, in other embodiments, the electronics housing 5004 may assume other cross-sectional shapes, such as oval or polygonal, without departing from the scope of the present disclosure. The electronics housing 5004 may 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) may be disposed on the bottom of the electronics housing 5004. The adhesive patch may be similar to the adhesive patch 105 of FIG. 1 and may therefore aid 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 including a shell 5006 and a mount 5008 matable with the shell 5006. The shell 5006 may be secured to the mount 5008 via a variety of methods, such as a snap-fit ​​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 to create a sealed interface therebetween.

[0086] The sensor control device 5002 may further include a sensor 5010 (partially visible) and a sharp 5012 (partially visible) used to aid in transdermal delivery of the sensor 5010 beneath the skin of a user during application of the sensor control device 5002. As shown, the sensor 5010 and corresponding portions of the sharp 5012 extend distally from a bottom (e.g., mount 5008) of the electronics housing 5004. The sharp 5012 may include a sharp hub 5014 configured to secure and carry the sharp 5012. As best seen in FIG. 10B, the sharp hub 5014 may include or otherwise define an engagement member 5016. To couple the sharp 5012 to the sensor control device 5002, the sharp 5012 may be advanced axially through the electronics housing 5004 until the sharp hub 5014 engages the top surface of the shell 5006 and the mating member 5016 extends distally from the bottom of the mount 5008. Once the sharp 5012 penetrates the electronics housing 5004, an exposed portion of the sensor 5010 may be received within a hollow or recessed (arcuate) portion of the sharp 5012. The remaining portion of the sensor 5010 is disposed within the interior of the electronics housing 5004.

[0087] The sensor control device 5002 may further include a sensor cap 5018, which is shown exploded or removed from the electronics housing 5004 in FIGS. 10A-10B. 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 serve to provide a hermetic barrier that surrounds the exposed portions of the sensor 5010 and the sharps 5012 and protects against gas chemical sterilization. As shown, the sensor cap 5018 may comprise a generally cylindrical body having a first end 5020a and a second end 5020b opposite the first end 5020a. The first end 5020a may be open to provide access into an inner chamber 5022 defined within the body. In contrast, the second end 5020b may be closed and may provide or otherwise define an engagement portion 5024. As described herein, the engagement portion 5024 may help to fit the sensor cap 5018 to 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 may help to remove the sensor cap 5018 from the sensor control device 5002 when the cap is removed from the sensor applicator.

[0088] The sensor cap 5018 may be removably coupled to the electronics housing 5004 at or near the bottom of the mount 5008. More specifically, the sensor cap 5018 may be removably coupled to a mating member 5016 extending distally from the bottom of the mount 5008. In at least one embodiment, for example, the mating member 5016 may define a set of male threads 5026a (FIG. 10B) that are matable with a set of female threads 5026b (FIG. 10A) defined by the sensor cap 5018. In some embodiments, the male and female threads 5026a,b may comprise a flat thread design (e.g., lack of helical curvature), which may prove advantageous in molding the part. Alternatively, the male and female threads 5026a,b may include a helical thread engagement. Thus, the sensor cap 5018 may be threadedly coupled to the sensor control device 5002 at the mating member 5016 of the sharps hub 5014. In other embodiments, the sensor cap 5018 may be removably coupled to the mating member 5016 via 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 minimal separation force (e.g., axial or rotational force).

[0089] In some embodiments, the sensor cap 5018 may comprise a monolithic (single) structure extending between the first and second ends 5020a,b. However, in other embodiments, the sensor cap 5018 may comprise two or more components. In the illustrated embodiment, for example, the sensor cap 5018 may include a sealing ring 5028 positioned at the first end 5020a and a desiccant cap 5030 disposed at the second end 5020b. The sealing ring 5028 may be configured to help seal the internal chamber 5022, as described in more detail below. In at least one embodiment, the sealing ring 5028 may include an elastomeric O-ring. The desiccant cap 5030 may house or include a desiccant to help maintain a preferred humidity level within the internal chamber 5022. The desiccant cap 5030 may also define or otherwise provide an engagement portion 5024 for the sensor cap 5018.

[0090] 11A-11C are progressive 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, the sensor control device may be loaded into the sensor applicator 102. With reference to FIG. 11A, the sharps hub 5014 may include or otherwise define a hub snap tab 5302 configured to aid in coupling the sensor control device 5002 to the sensor applicator 102. More specifically, the sensor control device 5002 may be advanced into the sensor applicator 102, and the hub snap tab 5302 may be received by a corresponding arm 5304 of a sharps carrier 5306 positioned within the sensor applicator 102.

[0091] 11B, the sensor control device 5002 is shown received by a sharps 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 may be coupled to the sensor applicator 102. In some embodiments, the applicator cap 210 and the housing 208 may have an opposing, matable set of threads 5308 that allow the applicator cap 210 to be threaded onto the housing 208 in a clockwise (or counterclockwise) direction, thereby securing the applicator cap 210 to the sensor applicator 102.

[0092] As shown, the sheath 212 is also positioned within the sensor applicator 102, which may 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 may include a threaded engagement between the applicator cap 210 and the sheath 212. More specifically, one or more internal threads 5312a may be defined or otherwise provided on an inner surface of the applicator cap 210, and one or more external threads 5312b may be defined or otherwise provided on the sheath 212. The internal threads 5312a and external threads 5312b may be configured to thread together when the applicator cap 210 is threaded onto the sensor applicator 102 at the threads 5308. The female threads 5312a and male threads 5312b may have the same thread pitch as the threads 5308 that allow the applicator cap 210 to be screwed onto the housing 208.

[0093] 11C , applicator cap 210 is shown fully threaded (coupled) to housing 208. As shown, applicator cap 210 may further provide, or otherwise define, a cap post 5314 centrally located within and extending proximally from a bottom of applicator cap 210. Cap post 5314 may be configured to receive at least a portion of sensor cap 5018 when applicator cap 210 is threaded onto 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 may 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 sharps 5012 are sealed within the sensor cap 5018, the chemicals used during the gas chemical sterilization process cannot interact with the enzymes, chemicals, and biologics provided on the tail 5104 and other sensor components such as the membrane coating that regulates analyte influx.

[0095] 12A-12C are progressive cross-sectional side views illustrating assembly and disassembly of an alternative embodiment of a sensor applicator 102 having a sensor control device 5002, in accordance with one or more additional embodiments. The fully assembled sensor control device 5002 may be loaded into the sensor applicator 102 by coupling the hub snap tabs 5302 to the arms 5304 of a sharps carrier 5306 positioned within the sensor applicator 102, generally as described above.

[0096] In the illustrated embodiment, the sheath arm 5604 of the sheath 212 may 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 "lock" detent and the second detent 5702b may alternatively be referred to as a "fire" detent. When the sensor control device 5002 is initially installed within the sensor applicator 102, 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 102 in the fired position.

[0097] In FIG. 12B , applicator cap 210 is aligned with and advanced toward housing 208 such that sheath 212 is received within applicator cap 210. Instead of rotating applicator cap 210 relative to housing 208, threads of applicator cap 210 may be snapped into corresponding threads of housing 208 to couple applicator cap 210 to housing 208. Axial cuts or slots 5703 (one shown) defined in applicator cap 210 may allow a portion of applicator cap 210 near the threads to flex outwardly to snap into engagement with threads of housing 208. Once applicator cap 210 is snapped onto housing 208, sensor cap 5018 may correspondingly snap into cap post 5314.

[0098] 11A-11C , the sensor applicator 102 may 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 the base of the sheath 212 configured to interact with one or more ribs 5706 (two shown) and a shoulder 5708 defined near the base of the applicator cap 210. The rib 5704 may be configured to interlock 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 may be rotated (e.g., clockwise), which positions rib 5704 of sheath 212 between rib 5706 and shoulder 5708 of applicator cap 210, thereby "locking" applicator cap 210 in place until a user removes applicator cap 210 for use by counter-rotating applicator cap 210. The engagement of rib 5704 between rib 5706 and shoulder 5708 of applicator cap 210 may also prevent sheath 212 from prematurely folding.

[0099] In Figure 12C, the applicator cap 210 has been removed from the housing 208. As with the embodiment of Figures 21A-21C, the applicator cap 210 can be removed by counter-rotating the applicator cap 210, which correspondingly rotates the cap post 5314 in the same direction to unscrew the sensor cap 5018 from the mating member 5016, generally as described above. Additionally, when the sensor cap 5018 is removed from the sensor control device 5002, the sensor 5010 and a distal portion of the sharp 5012 are exposed.

[0100] When the applicator cap 210 is unscrewed from the housing 208, the ribs 5704 defined on the sheath 212 may slidingly engage the tops of the ribs 5706 defined on the applicator cap 210. The tops of the ribs 5706 may provide corresponding sloped surfaces that effect upward movement of the sheath 212 as the applicator cap 210 is rotated, causing the sheath arms 5604 to bend out of engagement with the first detent 5702a and be received into the second detent 5702b. As the sheath 212 moves to the second detent 5702b, the radial shoulder 5614 moves out of radial engagement with the carrier arms 5608, thereby allowing the passive spring force of the springs 5612 to push the sharps carrier 5306 upward, disengaging the carrier arms 5608 from engagement with the grooves 5610. As the sharps carrier 5306 moves upward within the housing 208, the engaging member 5016 may correspondingly retract until it is flush, substantially flush, or near-flush with the bottom of the sensor control device 5002. At this point, the sensor applicator 102 is in the fired position. Thus, in this embodiment, removal of the applicator cap 210 correspondingly retracts the engaging member 5016.

[0101] 13A-13F show exemplary details of an embodiment of the internal device mechanism, including "firing" the applicator 216 to apply the sensor control device 222 to the user and safely retracting the sharp 1030 into the used applicator 216. Taken together, these figures depict an exemplary sequence of driving the sharp 1030 (carrying a sensor coupled to the sensor control device 222) into the user's skin, withdrawing the sharp while leaving the sensor in operative contact with the user's interstitial fluid, and adhering the sensor control device to the user's skin with an adhesive. Modifications of such activities for use with alternative applicator assembly embodiments and components can be understood by those skilled in the art with reference thereto. Additionally, the applicator 216 may be a sensor applicator having a one-piece or two-piece architecture as disclosed herein.

[0102] 13A, the sensor 1102 is supported within the sharp 1030, immediately above the user's skin 1104. Rails 1106 (optionally three of them) of the upper guide portion 1108 may be provided to control movement of the applicator 216 relative to the sheath 318. The sheath 318 is held by a detent portion 1110 within the applicator 216 such that an appropriate downward force along the longitudinal axis of the applicator 216 overcomes the resistance provided by the detent portion 1110, allowing the sharp 1030 and sensor control device 222 to translate along the longitudinal axis into (and onto) the user's skin 1104. Additionally, the catch arm 1112 of the sensor carrier 1022 engages the sharp retraction assembly 1024 to maintain the sharp 1030 in position relative to the sensor control device 222.

[0103] 13B, a user force is applied to overcome or override the detent portion 1110 and the sheath 318 collapses into the housing 314, driving the sensor control device 222 (along with associated components) 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 / sharps insertion process. The retention of the stop surface 1114 of the carrier arm 1112 against the complementary surface 1116 of the sharps retraction assembly 1024 maintains the position of the member with the return spring 1118 fully biased. According to an embodiment, rather than using a user force to drive the sensor control device 222 to translate downward along the longitudinal axis as indicated by arrow L, the housing 314 may include a button (e.g., but not limited to, a push button) that activates a drive spring (e.g., but not limited to, a coil spring) to drive the sensor control device 222.

[0104] In Figure 13C, the sensor 1102 and sharp 1030 have reached full insertion depth, where the carrier arm 1112 clears the inner diameter of the upper guide portion 1108. The compressed force of the coil return spring 1118 then drives the angled stop surface 1114 radially outward, releasing the force to drive the sharps carrier 1102 of the sharps retraction assembly 1024, pulling the sharps 1030 (slotted or otherwise configured) away from the user and away from the sensor 1102, as shown by arrow R in Figure 13D.

[0105] As shown in Figure 13E, once the sharp 1030 is fully retracted, the upper guide portion 1108 of the sheath 318 is set with the final locking portion 1120. As shown in Figure 13F, the used applicator assembly 216 is removed from the insertion site leaving the sensor control device 222 behind and the sharp 1030 safely secured inside the applicator assembly 216. The used applicator assembly 216 is now ready for disposal.

[0106] The movement of the applicator 216 when applying the sensor control device 222 is designed to provide the user with the sensation that both the insertion and retraction of the sharp 1030 are performed automatically by the internal mechanisms of the applicator 216. In other words, the present invention avoids the user experiencing the sensation of manually driving the sharp 1030 into the skin. Thus, when the user applies sufficient force to overcome the resistance from the detent portion of the applicator 216, the resulting movement of the applicator 216 is perceived as an automatic response to the applicator being "triggered." The user does not perceive that the user is supplying additional force to drive the sharp 1030 to pierce the skin, even though all the driving force is provided by the user and no additional biasing / driving means are used to insert the sharp 1030. As detailed above in FIG. 13C, retraction of the sharp 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 its components, including but not limited to sharps, sharps modules, and sensor modules embodiments, one skilled in the art will understand that said embodiments may be sized and configured for use with a sensor configured to sense an analyte level in a bodily fluid within the epidermis, dermis, or subcutaneous tissue of a subject. In some embodiments, for example, the sharps and distal portion of the analyte sensors disclosed herein may both be sized and configured to be positioned at a particular end depth (i.e., the furthest point of penetration within a tissue or layer of the subject's body, e.g., within the epidermis, dermis, or subcutaneous tissue). With respect to some applicator embodiments, one skilled in the art will understand that certain embodiments of the sharps may be sized and configured to be positioned at different end depths within the subject's body relative to a final end depth of the analyte sensor. In some embodiments, for example, the sharps may be positioned at a first end depth within the subject's epidermis prior to retraction, and the distal portion of the analyte sensor may be positioned at a second end depth within the subject's dermis. In other embodiments, the sharp may be positioned at a first end depth within the dermis of the subject and the distal portion of the analyte sensor may be positioned at a second end depth within the subcutaneous tissue of the subject prior to retraction. In yet other embodiments, the sharp may be positioned at a first end depth and the analyte sensor may be positioned at a second end depth prior to retraction, both of which are in the same layer or tissue of the subject's body.

[0108] Additionally, with respect to any of the applicator embodiments described herein, one of ordinary skill in the art will appreciate that the analyte sensor, as well as one or more structural components coupled to the analyte sensor, including but not limited to one or more spring mechanisms, may be positioned within the applicator in an off-center position relative to one or more axes of the applicator. In some applicator embodiments, for example, the analyte sensor and spring mechanism may be positioned in a first off-center position relative to the applicator axis on a first side of the applicator, and the sensor electronics may be positioned in a second off-center position relative to the applicator axis on a second side of the applicator. In other applicator embodiments, the analyte sensor, spring mechanism, and sensor electronics may be positioned in an off-center position relative to the applicator axis on the same side. 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 position relative to one or more axes of the applicator are possible and fully within the scope of the present disclosure.

[0109] Further details of suitable devices, systems, methods, components, and their operation with associated parts are described in International Publication No. WO 2018 / 136898 to Rao et al., International Publication No. WO 2019 / 236850 to Thomas et al., International Publication No. WO 2019 / 236859 to Thomas et al., International Publication No. WO 2019 / 236876 to Thomas et al., and U.S. Patent Application Publication No. 2020 / 0196919, filed June 6, 2019, each of which is incorporated by reference herein in its entirety. Further details regarding the applicator, its components, and variant embodiments thereof are described in U.S. Patent Application Publication Nos. 2013 / 0150691, 2016 / 0331283, and 2018 / 0235520, each of which is incorporated by reference in its entirety for all purposes. Further details regarding the sharps module, sharps, its components, and variant embodiments thereof are described in U.S. Patent Application Publication No. 2014 / 0171771, each of which is incorporated by reference in its entirety 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 of a chemical or composition that the sensor is designed to detect. For electrochemical sensors, this response can be in the form of a current (amperometric) or charge (coulometric). In other types of sensors, the response may be in a different form, such as photon intensity (e.g., optical 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 showing the in vitro sensitivity of an amperometric analyte sensor. In vitro sensitivity can be obtained by in vitro testing a sensor at various analyte concentrations and then performing regression (e.g., linear or nonlinear) or other curve fitting 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 electrical output current of the sensor, x is the analyte level (or concentration), m is the slope of the sensitivity, and b is the intercept of the sensitivity, where the intercept generally corresponds to the background signal (e.g., noise). For sensors with linear or substantially linear responses, the analyte level corresponding to a given current can be determined from the slope and intercept of the sensitivity. Sensors with nonlinear sensitivity require additional information to determine the analyte level resulting from the sensor's output current, and those skilled in the art are familiar with how to model nonlinear 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 the sensitivity of the sensor, are established for use in the calibration adjustment.

[0113] Certain in vivo analyte monitoring systems require calibration to be performed after the sensor is implanted in a user or patient, either by user intervention or by the system itself in an automated manner. 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 inputs it into the system. The system then 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 in an algorithmic process to convert the data collected by the sensor into a value indicative of the user's analyte level. This 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, a variable schedule, or as needed) may be required to maintain accuracy. While the embodiments described herein may incorporate some degree of user calibration for certain implementations, generally this is not preferred as it requires the user to perform painful or otherwise cumbersome BG measurements and can introduce user error.

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

[0115] Some in vivo analyte monitoring systems operate with sensors that are factory calibrated. Factory calibration refers to the determination or estimation of one or more calibration parameters prior to distribution to a user or healthcare professional (HCP). The calibration parameters may be determined by the sensor manufacturer (or the manufacturer of other components of the sensor control device, if the two entities are different). Many in vivo sensor manufacturing processes manufacture sensors in groups or batches called production lots, production stage lots, or simply lots. A single lot may contain thousands of sensors.

[0116] The sensor may include a calibration code or parameter that is derived or determined during one or more sensor manufacturing processes and may be coded 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 provided to the sensor. If the code is provided to the receiver (or other data processing device), user calibration during in vivo use of the sensor may be unnecessary or the frequency of in vivo calibration during sensor wear may be reduced. In embodiments in which the calibration code or parameter is provided on the sensor itself, the calibration code or parameter 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 monitoring systems operate with sensors that can be one or more of factory calibrated, system calibrated, and / or user calibrated. For example, the sensor may be equipped with a calibration code or parameters that can enable factory calibration. If the information is provided to the receiver (e.g., entered by a user), the sensor may operate as a factory calibrated sensor. If the information is not provided to the receiver, the sensor may operate as a user calibrated sensor and / or a system calibrated sensor.

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

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

[0120] According to the disclosed subject matter, each sensor in a sensor lot (in some cases not including the sample sensor used for in vitro testing) may be non-destructively inspected to determine or measure its characteristics, such as film thickness at one or more points on the sensor, and other characteristics, including physical characteristics such as surface area / volume of the active area, may be measured or determined. Such measurements or determinations may be performed in an automated manner, for example using an optical scanner or other suitable measurement device or system, and the determined sensor characteristics 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 codes assigned to each sensor. For example, for a calibration parameter defined as sensor sensitivity, the sensitivity is approximately inversely proportional to the film thickness, e.g., for a sensor having a measured film thickness that is about 4% greater than the average film thickness of sensors sampled from the same sensor lot as that sensor, the sensitivity assigned to that sensor in one embodiment is the average sensitivity determined from the sampled sensors divided by 1.04. Similarly, sensitivity is approximately proportional to the active area of ​​a sensor, so that for a sensor with a measured active area that is about 3% lower than the average active area of ​​sensors sampled from the same sensor lot, the assigned sensitivity for that sensor is the average sensitivity multiplied by 0.97. The assigned sensitivity may be determined from the average sensitivity from the sampled sensors by multiple successive adjustments for each inspection or measurement of the sensor. In certain embodiments, the inspection or measurement of each sensor may further include a measurement of the consistency or texture of the film in addition to the film thickness and / or surface area or volume of the active sensing area.

[0121] Further information regarding sensor calibration is provided in U.S. Patent Application Publication No. 2010 / 002302851 and U.S. Patent Application Publication No. 2019 / 0274598, each of which is incorporated by reference in its entirety.

[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 whose functions provide an interface to make the BLE module 5041 available to the computing 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, current active time, and software status. The analyte measurement data may include information such as current and past raw measurements, current and past values ​​after processing using appropriate algorithms or models, predictions and trends of measurement levels, comparisons of other values ​​to patient-specific averages, calls to action determined by algorithms or models, and other similar types of data.

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

[0124] A connection and subsequent communication session between two devices using a communication protocol such as BLE 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 may include a single channel or a set of channels, including, for example and without limitation, using a common clock and an agreed-upon set of channels determined by a channel or frequency hopping sequence. The communication sessions may use a similar amount of the available communication spectrum, and multiple such communication sessions may exist in close proximity. In certain embodiments, each set of devices in a communication session uses a different physical channel or set of channels to manage interference of devices in the same proximity.

[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 disclosed subject matter. 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 advertising periodically until a connection is established. The data receiving device 120 detects the advertising packet and scans and filters for the sensor 120 to connect through the data provided in the advertising packet. Next, the data receiving device 120 sends a scan request command, and the sensor 110 responds with a scan response packet providing additional details. Next, the data receiving device 120 sends a connection request using a Bluetooth device address associated with the data receiving device 120. The data receiving device 120 may also continuously request to establish a connection to the sensor 110 with a particular Bluetooth device address. The devices can then establish an initial connection and begin data exchange. The devices begin the process of initializing 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 may initialize a service, characteristics, and attribute discovery procedure. The data receiving device 120 may evaluate these characteristics of the sensor 110 and store them for use during subsequent connections. The devices then enable notification of customized security services to be used for mutual authentication of the sensor 110 and the data receiving device 120. The mutual authentication procedure can be automated and does not require user intervention. Following successful completion of the mutual authentication procedure, the sensor 110 sends a connection parameter update requesting the data receiving device 120 to use the connection parameter settings preferred by the sensor 110 and configured to maximize longevity.

[0127] The data receiving device 120 then executes a sensor control procedure to backfill historical data, current data, event logs, and factory data. As an example, for each type of data, the data receiving device 120 sends a request to initiate the backfill process. The request may specify a range of records defined, for example, based on measurements, timestamps, etc., as needed. The sensor 110 responds with the requested data until all previously untransmitted data in the memory of the sensor 110 is delivered to the data receiving device 120. The sensor 110 may respond to a backfill request from the data receiving device 120 that all data has already been transmitted. Once the backfill is complete, the data receiving device 120 may notify the sensor 110 that it is ready to receive periodic measurements. The sensor 110 may transmit measurements over multiple notification results on a recurring basis. As embodied herein, the multiple notifications may be redundant notifications to ensure that the data is transmitted correctly. Alternatively, the multiple notifications may 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, for example, when the sensor 110 is in an error state, an insertion failure state, or a sensor expired state. If the sensor 110 is not in those states, the sensor 110 can log 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 actively processing another command, the sensor 110 responds with a standard error response indicating that the sensor 110 is busy. Otherwise, the sensor 110 sends a response once the command is received. Additionally, the sensor 110 sends a success notification via the sensor control property to confirm that the sensor 110 received the command. The sensor 110 registers the shutdown command. At the next appropriate opportunity (e.g., depending on the current sensor state, as described herein), the sensor 110 shuts 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 enters a state 6005 associated with manufacturing the sensor 110. In the manufacturing state 6005, the sensor 110 may be configured for operation, e.g., the storage memory 5030 may be written to. At various times while in state 6005, the sensor 110 checks for a received command to proceed to the storage state 6015. Upon entering the storage state 6015, the sensor performs a software integrity check. While in the storage state 6015, the sensor may also receive a wake-up request command before proceeding to the insertion detection state 6025.

[0130] Upon entering state 6025, the sensor 110 may store information regarding devices authorized to communicate with the sensor set during startup or may initialize algorithms related to deriving and interpreting measurements from the sensing hardware 5060. The sensor 110 may also initialize a lifecycle timer responsible for maintaining an active count of the sensor's 110 operation time and may begin communicating with authorized devices to transmit recorded data. While in the insertion detection state 6025, the sensor may enter state 6030, in which the sensor 110 checks whether the operation time is equal to a predefined threshold. This operation time threshold may correspond to a timeout function for determining whether the insertion is successful. If the operation time reaches the threshold, the sensor 110 proceeds to state 6035, in which the sensor 110 checks whether the average data read is greater than a threshold amount corresponding to the expected amount of data read to trigger the detection of a successful insertion. If the amount of data read 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 Pair state 6055 .

[0131] The active pair state 6055 of the sensor 110 reflects the state while the sensor 110 is operating normally by recording measurements, processing the measurements, and reporting them accordingly. While in the active pair state 6055, the sensor 110 transmits measurements or attempts to establish a connection with the receiving device 120. The sensor 110 also increments the operating time. When the sensor 110 reaches a predetermined threshold operating time (e.g., the operating time reaches a predetermined threshold), the sensor 110 transitions to the active expired state 6065. The active expired state 6065 of the sensor 110 reflects the state while the sensor 110 has been operating for its maximum predetermined amount of time.

[0132] While in the active expired state 6065, the sensor 110 may generally perform actions related to finalization actions to ensure that collected measurements are securely transmitted to a receiving device as necessary. For example, while in the active expired state 6065, the sensor 110 may transmit collected data and, if a connection is not available, may increase efforts to discover and establish a connection with a nearby authenticated device. While in the active expired state 6065, the sensor 110 may receive a shutdown command in state 6070. If a shutdown command is not received, the sensor 110 may also check in state 6075 whether the operation time has exceeded a final operation threshold. The final operation threshold may be based on the battery life of the sensor 110. The normal termination state 6080 corresponds to a final operation of the sensor 110, ultimately shutting 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 a received RF field (e.g., an NFC field) drives the voltage of the power supply to the ASIC 5000 above 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 powers up the communication module 5040. The communication module 5040 is initialized and triggers a power-on self-test. The power-on self-test may include the ASIC 5000 communicating with the communication module 5040 using a prescribed 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 placed on the patient's body before a proper measurement can be made. First, the sensor 110 interprets a command to initiate a measurement configuration process, causing the ASIC 5000 to enter a measurement command mode. The sensor 110 then enters a measurement lifecycle state temporarily, performing several consecutive measurements to test whether the insertion was successful. The communication module 5040 or the ASIC 5000 evaluates the measurement results to determine successful insertion. Once the insertion is deemed successful, the sensor 110 enters a measurement state, where the sensor 110 begins to take periodic measurements using the sensing hardware 5060. If the sensor 110 determines that the insertion was not successful, the sensor 110 is triggered into an insertion failure mode, and the ASIC 5000 is commanded to return to a storage mode, while the communication module 5040 disables itself.

[0135] FIG. 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 may bundle updates for the data receiving device 120 or the sensor 110 with updates for applications running on the general-purpose data receiving device 130. Using available communication channels 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 for the data receiving device 120 or the sensor 110 and initiate installation of updates to the data receiving device 120 or the sensor 110. The general-purpose data receiving device 130 serves as an installation or update platform for the data receiving device 120 or the 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 the 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 updated 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 also 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 may periodically contact the application storefront server 160 to download and install updates.

[0137] After the multipurpose data receiving device 130 downloads the application update including the 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 prepare the software or firmware update for delivery to the data receiving device 120 or the sensor 110. As an example, the multipurpose data receiving device 130 may compress or segment data associated with the software or firmware update, or may encrypt or decrypt the firmware or software update, or perform an integrity check on the firmware or software update. The multipurpose data receiving device 130 transmits data for the firmware or software update to the data receiving device 120 or the sensor 110. The multipurpose data receiving device 130 may transmit a command to the data receiving device 120 or the sensor 110 to initiate the update. Additionally or alternatively, the multipurpose data receiving device 130 may provide notifications to a user of the multipurpose data receiving device 130 and may include instructions to facilitate the update, such as instructions to keep the data receiving device 120 and the multipurpose data receiving device 130 connected to and in close proximity 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 initiate 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 may place itself in a so-called "safe" mode with limited operational capabilities or reboot. Once the update is complete, the data receiving device 120 or the sensor 110 re-enters a standard operational mode or is reset. The data receiving device 120 or the sensor 110 may perform one or more self-tests to determine that the firmware or software update was successfully installed. The multipurpose data receiving device 130 can receive a notification of the successful update. The multipurpose data receiving device 130 can then report confirmation of the successful update to the remote application server 150.

[0139] In a particular embodiment, the storage memory 5030 of the sensor 110 includes a one-time programmable (OTP) memory. The term OTP memory may 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 may be pre-arranged into a number of pre-allocated memory blocks or containers. The containers are pre-allocated to a fixed size. If the storage memory 5030 is a one-time programming memory, the containers may be considered to be in a non-programmable state. Additional containers that have not yet been written to may be placed in a programmable or writable state. Containerizing the storage memory 5030 in this manner may improve the transportability of code and data to be written to the storage memory 5030. Updating the software of a device (e.g., a sensor device described herein) stored in an OTP memory may be performed by replacing only the code in a particular previously written container or containers with updated code written to a new container or containers, rather than replacing the entire code in the memory. In a second embodiment, the memory is not pre-arranged. Instead, the space allocated for data is dynamically allocated or determined as needed. Containers of various sizes where updates are expected can be defined so that incremental updates can be issued.

[0140] 16 illustrates an example operation and data flow diagram for over-the-air (OTA) programming of a storage memory 5030 in a sensor device 100 and use of the memory after OTA programming in execution of a process by the sensor device 110 in accordance with the disclosed subject matter. In the example 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, a 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] At 531, after receiving the OTA programming command, the microcontroller 5010 verifies the OTA programming command. The microcontroller 5010 may, for example, 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 OTA programming data. At 533, the microcontroller 5010 may reset the sensor device 110 to reinitialize the sensor device 110 to a 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 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 to mark one or more programming blocks or regions of the OTP memory 550 as invalid or inaccessible. The data written to the free or unused portions of the OTP memory may be used to replace the invalidated 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, the microcontroller 5010 may perform one or more software integrity checks to ensure that no errors were introduced into the programming blocks during the writing process. Once the microcontroller 5010 can determine that the data was written without error, the microcontroller 5010 can resume normal operation of the sensor device.

[0142] In the execution mode, the microcontroller 5010 can retrieve a programming manifest or profile from the rewritable memory 540 at 536. The programming manifest or profile may include a list of valid software programming blocks and may include a guide to program execution for the sensor 110. By following the programming manifest or profile, the microcontroller 5010 can determine which memory blocks of the OTP memory 550 are appropriate to execute and can avoid executing out-of-date or invalidated programming blocks or referencing out-of-date data. 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 by using variables stored in the memory.

[0143] As embodied herein, a first layer of security for communications between the analyte sensor 110 and other devices may be established based on security protocols dictated by and built into the communications protocol used for communication. Another layer of security may be based on communications protocols that require proximity of the communicating devices. Additionally, certain packets and / or certain data contained within a packet may be encrypted while other packets and / or data within the packet are otherwise encrypted or remain unencrypted. 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 within 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 also 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 a generated key to the sensitive data before transmitting the sensitive data. The generated key may be specific to the analyte sensor 110, specific to a pair of devices, specific to a communication session between the analyte sensor 110 and the other device, specific to a message transmitted during the communication session, or specific to a block of data contained within a message.

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

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

[0147] Analyte data associated with a user is at least partially sensitive data, since this information may be used for a variety of purposes, including health monitoring and medication dosing decisions. In addition to user data, the analyte monitoring system 100 may implement security enhancements against efforts by external parties to reverse engineering. The communication connection may be encrypted using a device-specific or session-specific encryption key. Encrypted or unencrypted communications between any two devices may be verified with a transmission integrity check built into the communication. The operation of the analyte sensor 110 may be protected from tampering by restricting access to read and write functions to the memory 5020 via the communication interface. The sensor may be configured to allow access only to known or "trusted" devices provided in a "white list," or only to devices that can provide a predefined code associated with the manufacturer or otherwise authorized user. The white list may represent an exclusive scope, meaning that no connection identifiers other than those included in the white list are used, or a preferred scope, where the white list is searched first, but other devices may still be used. The sensor 110 may further reject a connection request and shut down if the requester fails to complete a login procedure over the communication interface within a predefined time (e.g., within 4 seconds). These properties protect against certain denial of service attacks, particularly those against BLE interfaces.

[0148] As embodied herein, the analyte monitoring system 100 may employ periodic key rotation to further reduce the likelihood of key leakage and exploitation. The key rotation strategy employed by the analyte monitoring system 100 may be designed to support backward compatibility of field-deployed or distributed devices. As an example, the analyte monitoring system 100 may use keys for downstream devices (e.g., devices that are in the field or cannot feasibly provide updates) that are designed to be compatible with multiple generations of keys used by upstream devices.

[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 disclosed subject matter shown in FIG. 17, illustrating an exemplary data exchange 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 via a short-range communication protocol. The sensor 110 may be primarily dormant prior to step 605 to conserve its battery until a full wake-up is required. After waking up during step 610, the sensor 110 may collect data or perform other operations as appropriate for 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 may engage in a mutual authentication process 620. The mutual authentication process 620 may involve 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 capable of sufficient compliance with the agreed upon security framework described herein. Mutual authentication may be based on a mechanism for authenticating two or more entities to each other, with or without an online trusted third party, to verify the establishment of a secret key via challenge-response. Mutual authentication may be performed 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 may include a sensor-specific value and can be derived from a random value generated during manufacture. The sensor secret can be encrypted before or during transmission to prevent third parties from accessing the secret. The sensor secret 625 may be encrypted via one or more of the keys generated by or in response to the mutual authentication process 620. 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 or the data receiving device 120. In step 635, the sensor 110 can encrypt the data contained 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 the sensor 110 and the data receiving device 120 in an appropriate communication model. 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 deliver additional (including newly collected) data, and the data receiving device 120 can process the received data appropriately.

[0151] As described herein, the sensor 110 may be a device with limited processing power, battery supply, and storage. The encryption techniques (e.g., selection of cryptographic algorithms or implementations of algorithms) 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 with fewer limitations of this nature. Thus, the data receiving device 120 may employ more advanced and computationally intensive encryption techniques, such as cryptographic algorithms and implementations.

[0152] The analyte sensor 110 may be configured to modify its discoverability behavior to attempt to increase the probability that a receiving device receives a proper data packet and / or provides an acknowledgment signal or reduce limitations that may otherwise prevent the acknowledgment signal from being received. Modifying the discoverability behavior of the analyte sensor 110 may include, for example, without limitation, modifying how often connection data is included in a data packet, modifying how often data packets are transmitted in general, lengthening or shortening a broadcast window for a data packet, modifying the amount of time the analyte sensor 110 listens for an acknowledgment signal or a scan signal after a broadcast, including a direct transmission (e.g., through one or more attempted transmissions) to one or more devices that previously communicated with the analyte sensor 110 and / or one or more devices on a whitelist, modifying the transmit power associated with the communication module when broadcasting a data packet (e.g., to increase the range of the broadcast or reduce energy consumed to extend 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 similarly adjust parameters related to the device's listening behavior to increase the likelihood of receiving data packets containing the 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 operate its communications hardware. The second window refers to the rate at which the analyte sensor 110 is configured to actively transmit (e.g., broadcast) data packets. As an example, the first window may indicate that the analyte sensor 110 operates its communications hardware to transmit and / or receive data packets (including connection data) during the first 2 seconds of each 60 second period. The second window may indicate that during each 2 second window, the analyte sensor 110 transmits a data packet every 60 milliseconds. The remaining time during the 2 second window, the analyte sensor 110 is scanning. The analyte sensor 110 may lengthen or shorten either window to modify the discoverability behavior of the analyte sensor 110.

[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 state of the analyte sensor 110, and / or by applying rules based on the state of the analyte sensor 110. For example, when the battery level of the analyte sensor 110 falls below a certain amount, the rule may cause the analyte sensor 110 to reduce the power consumed by the broadcast process. As another example, configuration settings associated with 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 associated with the transmission capabilities or processes of the communication hardware of the analyte sensor 110 may be modified, including, but not limited to, the transmission rate, frequency, and timing. As another example, when the analyte data indicates that the subject is experiencing or about to experience a negative health event, the rule may cause the analyte sensor 110 to increase its discoverability and alert receiving devices of the negative health event.

[0155] As embodied herein, certain calibration characteristics for the sensing hardware 5060 of the analyte sensor 110 may be adjusted based on external or interval environmental characteristics, as well as to compensate for decay of the sensing hardware 5060 during periods of not being used (e.g., "storage time" prior to use). The calibration characteristics of the sensing hardware 5060 may be adjusted autonomously by the sensor 110 (e.g., by operation of the ASIC 5000 to modify characteristics in the memory 5020 or storage 5030) or may be adjusted by other devices of the analyte monitoring system 100.

[0156] As an example, the sensor sensitivity of the sensing hardware 5060 may be adjusted based on external temperature data or time since manufacture. When external temperature is monitored during storage of the sensor, the disclosed subject matter may adaptively change compensation to the sensor sensitivity over time as the device experiences changing storage conditions. By way of example and not limitation, adaptive sensitivity adjustments may be performed in an "active" storage mode in which the analyte sensor 110 periodically wakes up to measure temperature. These features may conserve the battery of the analyte device and extend the life of the analyte sensor. At each temperature measurement, the analyte sensor 110 may calculate a sensitivity adjustment for that period based on the measured temperature. The temperature weighted adjustment values ​​may 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 manufacture of the sensor 110 (which can be written to the storage 5030 of the ASIC 5000) or the sensing hardware 5060 and modify the sensor sensitivity or other calibration characteristics according to one or more known decay rates or formulas.

[0157] Additionally, for purposes of illustration and not limitation, as embodied herein, the sensor sensitivity adjustment may account for other sensor conditions, such as sensor drift. The sensor sensitivity adjustment may be hard-coded into the sensor 110 during manufacturing, for example, based on an estimate of how much the average sensor drifts in the case of sensor drift. The sensor 110 may use a calibration function having time-varying functions for sensor offset and gain, which may account for drift over the period of wear of the sensor. Thus, the sensor 110 may utilize a device-dependent function that describes the drift of the sensor 110 over time, and a function used to convert interstitial current to interstitial glucose, which may represent sensor sensitivity and may be device-specific combined with a baseline glucose profile. Such functions to account for sensor sensitivity and drift may improve the accuracy of the sensor 110 over the period of wear without 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 may 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 may act on the output of the machine learning models trained to interact with the raw measurements. As an example, the models may be used to detect, predict, or recommend events based on the raw measurements and the type of analyte detected by the sensing hardware 5060. The events may include the initiation or completion of a physical activity, a meal, the application of a medical procedure or medication, 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 a firmware or software update. The model may be periodically refined, such as by the manufacturer of the sensor 110 or the operator of the analyte monitoring system 100, based on data received from the sensor 110 and the data receiving device of an individual user or a population of users. In certain embodiments, the sensor 110 includes sufficient computer components to support further training or refinement of the machine learning model, such as based on characteristics specific to the user to which the sensor 110 is attached. The machine learning model may include models trained using or incorporating, by way of example and not limitation, decision tree analysis, gradient boosting, ada boosting, artificial neural networks or variations thereof, linear discriminant analysis, nearest neighbor analysis, support vector machines, supervised or unsupervised classification, and the like. The model may also include algorithmic or rule-based models in addition to machine learning models. Model-based processing may be performed by the data receiving device 120 or other devices, including the general-purpose data receiving device 130, upon receiving data from the sensor 110 (or other downstream devices).

[0160] The data transmitted between the sensor 110 and the data receiving device 120 may include raw measurements or processed measurements. The 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 convey notifications to a user based on the raw measurements or processed measurements, or may display alarms as they are 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 single reading that exceeds or does not meet a threshold), analyte value trends (e.g., average readings over a set period of time that exceed or do not meet a threshold, slope), analyte value predictions (e.g., an algorithmic calculation based on an analyte value exceeds or does not meet a threshold), sensor warnings (e.g., a suspected malfunction is detected), communication warnings (e.g., no communication between the sensor 110 and the data receiving device 120 for a threshold period of time, an unknown device attempting to initiate or failing to initiate a communication session with the sensor 110), reminders (e.g., a reminder to charge the data receiving device 120, take medication, or perform other activities), and other warnings of a similar nature. For purposes of illustration and not limitation, as embodied herein, the alarm parameters described herein may be configurable by the user, or may be fixed during manufacture, or may be a combination of user-settable and non-user-settable parameters.

[0161] According to aspects of the disclosed subject matter, an in vivo analyte sensor and method are provided for detecting alcohol levels, including but not limited to ethanol levels. As used herein, the term "alcohol" and grammatical variations thereof refer to any primary, secondary, or tertiary alcohol. For example, the alcohol sensor of the present disclosure can detect ethanol, methanol, butanol, propanol, isopropyl alcohol, and the like, and any combination thereof.

[0162] As used herein, the term "reference electrode" may refer to either a reference electrode or an electrode that functions as both a reference electrode and a counter electrode. Similarly, as used herein, the term "counter electrode" may refer to both a counter electrode and a counter electrode that also functions as a reference electrode.

[0163] The sensor 110 described herein may include a sensing element including one or more electrodes configured to detect one or more analyte levels in a bodily fluid, examples of which are shown in FIGS. 18A-20. The one or more electrodes may include one or more enzyme response elements. For example, as embodied herein, the sensor 110 may detect an alcohol level in a bodily fluid. In another example, the sensor 110 may detect an alcohol level and a glucose level in a bodily fluid. In yet another example, the sensor 110 may detect an alcohol level and a ketone level in a bodily fluid. The sensor 110 may include one working electrode capable of detecting alcohol and / or another working electrode capable of detecting glucose, ketone, lactate, and / or any other analyte level. In some examples, the sensor 110 may include two or more sensing elements configured to detect two or more analyte levels in a bodily fluid. The sensor 110 may be referred to as an "analyte sensor."

[0164] An individual's in vivo alcohol concentration can change dramatically based on alcohol consumption or various physiological factors. For example, alcohol can be metabolized at different rates by individuals, which can cause alcohol levels to vary between individuals consuming the same dose of alcohol per body weight. The equilibrium concentration of alcohol depends at least on water content, blood flow rate, and body weight. Given that alcohol crosses biological membranes, alcohol can flow from the bloodstream to all tissues and fluids. The flow rate can be proportional to the water content of the tissues and fluids. Furthermore, as noted above, alcohol concentration can affect the function of one or more other analytes of an individual, thereby affecting the health or physiological condition of the individual. For example, any of the sensor systems and analyte sensor configurations described below can feature one or more enzymes used to detect alcohol.

[0165] Ex vivo alcohol measurements may be made by taking a physical blood sample, urine sample, saliva sample, sweat or perspiration sample, or breath test. However, these measurements are static in time and may, in some cases, reflect erroneous or inaccurate results. Analyte sensors, on the other hand, are dynamic and updated over time. Alcohol sensors respond to in vivo alcohol levels and can provide "continuous" measurements. Alcohol sensors can provide multiple alcohol concentration measurements over continuous periods, such as seconds, minutes, or hours to days, weeks, or months.

[0166] An individual wearing a continuous alcohol sensor can access real-time alcohol level information and make various decisions based thereon, such as whether to drive a vehicle and / or whether other analyte levels, such as glucose, are dysregulated based on the alcohol level. For example, the alcohol sensor may be used to monitor, test, and / or evaluate alcohol levels in individuals suffering from alcohol misuse, abuse, or dependence. Alcohol levels may be monitored by the individual themselves, by a medical professional, or by a law enforcement professional.

[0167] A display unit of the sensor or reader device may be used to provide instructions, suggestions, guidance, recommendations, and / or any other output associated with or corresponding to the alcohol concentration. Appropriate processing algorithms, processors, memory, electronic components, etc. may reside in either a trusted computer system, a remote terminal, a cloud server, the reader device, and / or in the housing of the sensor itself. The guidance, recommendations, output, and / or the like may be shown on a display unit or graphical user interface in electronic communication with the sensor or one or more components of the sensor system. The display unit or device may be a dedicated reader device, or a user equipment such as a mobile device. Alternatively, the display unit or device may be a third party server, a cloud server, or a remote terminal in communication with various software applications accessible by a medical professional. One of the dedicated reader device, user equipment, or server may further relay the data or output to one or more secondary devices, such as a smart home device, a wearable watch or device, a personal health monitor, etc.

[0168] As embodied herein, a reader device may include a processor, a memory, an input / output interface, and a communication interface. The processor includes hardware for executing instructions, such as those that constitute a computer program. By way of example and not limitation, to execute instructions, the processor may retrieve (or fetch) instructions from an internal register, an internal cache, a memory, or storage, decode and execute them, and then write one or more results to an internal register, an internal cache, a memory, or storage. The processor may also include one or more internal caches for data, instructions, or addresses. The one or more processors may include one or more arithmetic logic units (ALUs) or may be multi-core processors.

[0169] As embodied herein, memory includes a main memory for storing instructions for the processor to execute or data for the processor to operate on. By way of example and not limitation, the reader device may load instructions from a storage or another source into the memory. The processor may then load the instructions from the memory into an internal register or cache. To execute the instructions, the processor may retrieve the instructions from the internal register or cache and decode them. During or after the execution of the instructions, the processor may write one or more results (which may be intermediate or final results) into the internal register or cache. The processor may then write one or more of those results into the memory. For example, the memory may include a random access memory (RAM). The RAM may be a volatile memory, a dynamic RAM (DRAM), or a static RAM (SRAM). The RAM may be a single-port or multi-port RAM, and the memory may include one or more memories.

[0170] As described herein with reference to FIG. 1A, the sensor 110 may be at least partially inserted into the dermis or subcutaneous layer of the skin. The sensor 110 may include a sensor tail of sufficient length to insert to a desired depth within the interstitial fluid. The sensor tail may include at least one working electrode and one or more active areas (sensing regions / spots or sensing layers) disposed thereon that are active for sensing alcohol (or possibly one or more additional analytes). For example, the active areas may be in the form of one or more separate spots. The number of separate spots may range, for example, from one to a dozen spots. The one or more separate spots may be spaced apart from each other by about 0.1 mm. 2 ~about 0.5mm 2 , about 0.25mm 2 ~about 0.75mm 2 , about 0.05mm 2 ~ approx. 0.2 mm 2 etc., approximately 0.01 square millimeters (mm 2 ) ~ approx. 1.00 mm 2 or any other smaller or larger value.

[0171] One or more active areas may include one or more enzymes used to facilitate detection of alcohol. The active areas may, for example, include a polymeric material to which one or more enzymes are chemically bound (e.g., covalently bound, ionically bound, etc.) or otherwise immobilized (e.g., not bound in a matrix). For example, each active area may be overcoated with a mass-limited biocompatible membrane, and / or an electron transfer agent to facilitate at least detection of alcohol.

[0172] As embodied herein, alcohol levels may be monitored in any biological fluid of interest, such as dermal fluid, interstitial fluid, plasma, blood, lymphatic fluid, synovial fluid, cerebrospinal fluid, saliva, bronchoalveolar lavage, amniotic fluid, etc.

[0173] As shown in FIG. 1A, the sensor control unit 102 can manually or automatically transfer data acquired by the sensor 110 to the reader device 120. For example, the alcohol concentration data can be communicated automatically or periodically after a certain period of time has passed, with the data stored in memory until transmission (e.g., every few seconds, every minute, every five minutes, or other predetermined period of time). The sensor control unit 102 may also communicate with the reader device 120 according to a non-set schedule based on the wearer's or user's actions or requests. For example, when the sensor electronics are brought within communication range of the reader device 120, data can be communicated from the sensor control unit 102 using NFC or RFID technology. Additionally or alternatively, Bluetooth may be used to facilitate communication of data from the sensor control unit 102 to the reader device 120. The data may remain stored in the memory of the sensor control device 102 until the data is communicated to the reader device 120. In one example, the data may be stored in the memory of the sensor control device 102 for up to eight hours. In other examples, the data may be stored for up to 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 6 hours, 10 hours, 12 hours, 24 hours, or any other number of hours. The data may then be transmitted from the sensor control device 102 to the reader device 120 when the sensor control device 102 is within a given distance from the reader device 120.

[0174] For purposes of illustration and not limitation, as embodied herein, an exemplary alcohol sensor may include active areas located on one or both sides of a single working electrode, or on one or both sides of two or more separate working electrodes. In other examples, an alcohol sensor may use one or more working electrodes and one or more other electrodes, such as a reference electrode. Sensor configurations having a single working electrode are described below with reference to FIGS. 18A-18C. Each of these sensor configurations may suitably incorporate one or more alcohol-responsive active areas. Sensor configurations having multiple working electrodes are described hereafter with reference to FIGS. 19 and 20. When multiple working electrodes are present, one or more alcohol-responsive active areas are disposed on one or more of the multiple working electrodes, and one or more working electrodes may be used to detect another analyte of interest in coordination with the detection of alcohol levels.

[0175] When a single working electrode is included in the alcohol sensor, a counter electrode and a reference electrode may also be included in the alcohol sensor. Thus, the alcohol sensor may include a total of three electrodes with a single working electrode. For example, a working electrode and a second electrode such as a counter electrode or a reference electrode may be included. In one example, the counter electrode and the reference electrode may be combined into one second electrode. In an example including two or three electrodes, one or more active areas of the alcohol sensor may contact the working electrode. The one or more active areas may include, for example, one or more enzymes.

[0176] The various electrodes may be at least partially stacked or layered on one another. For example, the various electrodes may be laterally spaced apart from one another on the sensor tail. Similarly, the associated active areas on each electrode may be vertically stacked on top of one another or laterally spaced apart. The various electrodes may be electrically insulated from one another by a dielectric material or similar insulator.

[0177] FIG. 18A is a cross-sectional view illustrating an exemplary analyte sensor including a single active area as embodied herein. For example, FIG. 18A illustrates a two-electrode sensor configuration. The analyte sensor illustrated in FIG. 18A can detect, for example, at least an alcohol level. The sensor 1800 of FIG. 18A can be similar to the sensor 110 illustrated in FIG. 1A. The sensor 1800 can include a substrate 1812 disposed between a working electrode 1814 and a counter / reference electrode 1816. In some examples, the working electrode 1814 and the counter / reference electrode 1816 can be disposed on the same side (e.g., front or back) of the substrate 1812 with a dielectric material interposed therebetween. The active area 1818 can be disposed as one or more layers on a portion of the working electrode 1814. Additionally, the active area 1818 can be a single spot or multiple spots configured for detection of one or more analytes of interest. One or more enzymes can be present on a single spot or multiple spots of the active area 1818.

[0178] In addition, as shown in FIG. 18A, the membrane 1820 can overcoat at least the active area 1818. The membrane 1820 can also overcoat some or all of the working electrode 1814, the counter / reference electrode 1816, or the entire analyte sensor 1800. One or both sides of the analyte sensor 1800 may be overcoated with the membrane 1820. The membrane 1820 may include one or more polymeric membrane materials that can restrict the flow of analyte to the active area 1818. For example, the sensor 1800 can assay alcohol by using at least one of coulometric, amperometric, voltammetric, potentiometric electrochemical, or iontophoretic (including reverse iontophoretic) detection.

[0179] FIG. 18B is a cross-sectional view illustrating an exemplary analyte sensor including a single active area as embodied herein. FIG. 18C is a cross-sectional view illustrating an exemplary analyte sensor including a single active area as embodied herein. For example, FIGS. 18B and 18C show a three-electrode sensor configuration. Both FIGS. 18B and 18C show a working electrode 1814, a counter or reference electrode 1816, and an additional electrode 1817. The additional electrode 1817 can be either another counter / reference electrode or another working electrode. The additional electrode 1817 can be disposed on either the working electrode 1814 or the counter / reference electrode 1816, with a separating layer of dielectric material disposed therebetween. As shown in FIG. 18B, dielectric layers 1819a, 1819b, and 1819c separate the electrodes 1814, 1816, and 1817 from one another to provide electrical insulation. 18C, at least one of the electrodes 1814, 1816, and 1817 may be located on opposite sides of the substrate 1812. Thus, the working electrode 1814 and the counter electrode 1816 may be disposed on opposite sides of the substrate 1812, and the reference electrode 1817 is disposed on one of the electrodes 1814 or 1816 and spaced therefrom by a dielectric material.

[0180] As embodied herein, the working electrode 1814 and the reference electrode 1816 may be disposed on opposite sides of the substrate 1812, and the counter electrode 1817 may be disposed on one of the electrodes 1814 or 1816 and spaced therefrom by a dielectric material. In yet another embodiment, the reference electrode or the counter electrode 1816 may be disposed on one side of the substrate 1812, and the working electrode 1814 may be disposed on the opposite side. A reference material layer 1830, which may be comprised of silver (Ag) or silver chloride (AgCl), may be present on the electrode 1817. The reference material layer 1830 may be located anywhere else on the electrode 1817, electrode 1814, or electrode 1816.

[0181] 18B and 18C, the analyte sensors 1801 and 1802 may include one or more enzymes in an active area 1818. In some examples, the active area 1818 may include multiple spots or a single spot configured for detection of at least alcohol. The analyte sensors 1801 and 1802 may, for example, assay for alcohol, or one or more additional analytes, by coulometric, amperometric, voltammetric, potentiometric, electrochemical, or iontophoretic detection techniques.

[0182] 18B and 18C, the membrane 1820 may overcoat the active area 1818 as well as other sensor components in the sensors 1801 and 1802. The additional electrode 1817 may also be overcoated with the membrane 1820. Although FIGS. 18B and 18C show all of the electrodes 1814, 1816, and 1817 as being overcoated with the membrane 1820, in other examples, only the working electrode 1814 may be overcoated, or only the working electrode 1814 and one other electrode may be overcoated. The thickness of the membrane 1820 on each of the electrodes 1814, 1816, and / or 1817 may be the same or different. For example, the amount of surface area of ​​each of the electrodes 1814, 1816, and / or 1817 that the membrane 1820 overcoats may be the same or different. One or both sides of the analyte sensors 1801 and 1802 may be overcoated with the membrane 1820. Alternatively, the entire analyte sensors 1801 and 1802 may be overcoated.

[0183] FIG. 19 is a cross-sectional view illustrating an exemplary analyte sensor including two active areas embodied herein. As shown in FIG. 19, the alcohol sensor 1900 has two working electrodes, a reference electrode, and a counter electrode. The sensor 1900 includes working electrodes 1904 and 1906 disposed on opposite sides of a substrate 1902. An active area 1910 is disposed on the surface of the working electrode 1904, and an active area 1912 is disposed on the surface of the working electrode 1906. One or more enzymes configured to detect alcohol may be present in the active areas 1910 and 1912. For example, one or more of the active areas 1910 or 1912 may be configured to detect alcohol concentration and another analyte of interest, such as glucose, lactate, or ketones. The counter electrode 1920 may be electrically insulated from the working electrode 1904 by a dielectric layer 1922, and the reference electrode 1921 may be electrically insulated from the working electrode 1906 by a dielectric layer 1923. Outer dielectric layers 1930 and 1932 are disposed on the reference electrode 1921 and counter electrode 1920, respectively. A membrane 1940 may overcoat at least the active areas 1910 and 1912. Other components of the analyte sensor 1900 may be overcoated with the membrane 1940, and / or one or both sides of the analyte sensor 1900, or portions thereof, may be overcoated with the membrane 1940. Similar to the analyte sensors 1800, 1801, and 1802 shown in FIGS. 18A-18C, the sensor 1900 may be operable to assay at least alcohol via coulometric, amperometric, voltammetric, potentiometric, or iontophoretic techniques.

[0184] As embodied herein, alternative sensor configurations different from that shown in Figure 19 may include multiple working electrodes and a combined counter / reference electrode instead of separate counter and reference electrodes 1920 and 1921. In other examples, the positioning of the counter electrode 1920 and reference electrode 1921 may be reversed from that shown in Figure 19. Additionally, working electrodes 1904 and 1906 may be on the same side of substrate 1902.

[0185] 18A-18C and 19 have been primarily directed to analyte sensor configurations having one or two working electrodes, in other examples, more than two working electrodes may be used by an analyte sensor. The additional working electrodes may provide additional active areas and corresponding sensing capabilities.

[0186] Additionally, although FIGS. 18A-18C and 19 depict a planar substrate (e.g., substantially flat) having electrodes and active areas disposed thereon, the analyte sensor may have a variety of other configurations. For example, the substrate may be substantially non-planar (e.g., curved, semi-hemispherical, or spherical), cylindrical, spiral, other irregular shapes, or any combination thereof. Similarly, one or more electrodes may be substantially non-planar (e.g., relatively curved, semi-hemispherical, or spherical), cylindrical, spiral, other irregular shapes, or any combination thereof. The electrodes may be arranged in layers, concentric circles, or any other arrangement. The sensing region disposed on the working electrode may cover at least a portion of the working electrode as a single layer or as individual regions of various shapes, such as square, circular, semi-circular, arcuate, rectangular, polygonal, or other irregular shapes.

[0187] As embodied herein, an electron transfer agent may be present in one or more of the active areas of the alcohol sensor. A suitable electron transfer agent may help facilitate the transfer of electrons to the working electrode when the alcohol analyte undergoes an oxidation-reduction reaction. The electron transfer agent in each active area may determine the observed oxidation-reduction potential for the alcohol analyte.

[0188] FIG. 20 is a cross-sectional view illustrating an exemplary analyte sensor including two active areas as embodied herein. The analyte sensor configuration of FIG. 20 may be similar to FIG. 18C, with FIG. 20 including two active areas 2018a, 2018b. As shown in FIG. 20, the analyte sensor 2000 includes active areas 2018a and 2018b on a surface of a working electrode 2014. The active area 2018a includes a first electron transfer agent and a first analyte-responsive enzyme bound to the active area 2018a. The active area 2018b similarly includes a second electron transfer agent and a second analyte-responsive enzyme bound to the active area 2018b. As embodied herein, the first and second electron transfer agents may differ in composition to provide a separation of the redox potentials of the first active area 2018a and the second active area 2018b. For example, active area 2018b may include an alcohol responsive enzyme, such as ketone reductase, while active area 2018a may include a glucose responsive enzyme, such as glucose oxidase.

[0189] The redox potentials of the first active area 2018a and the second active area 2018b may be sufficiently separated to allow a first independent signal to be generated by the first active area 2018a and a second independent signal to be generated by the second active area 2018b. Thus, the analyte sensor 2000 may be operated at a first potential where a redox reaction occurs in the first active area 2018a but not in the second active area 2018b. A first analyte, such as glucose, may be selectively detected at or above the redox potential of the first active area 2018a, provided that the applied potential is not high enough to promote a ketone reductase reaction with the second active area 2018b. The concentration of the first analyte may be determined from the generated signal by referencing a lookup table or calibration curve.

[0190] Similarly, the redox potential of the second active area 2018b may occur simultaneously or nearly simultaneously in both the first active area 2018a and the second active area 2018b. As a result, a signal generated at or above the redox potential of the second active area 2018b may include a composite signal having signal contributions from both the first active area 2018a and the second active area 2018b. To determine the concentration of a second analyte, such as alcohol, from the composite signal, the signal from the first active area 2018a at or above the corresponding redox potential may be subtracted from the composite signal to provide a difference signal associated only with the second active area 2018b. Once the difference signal associated with the second active area 2018b is determined, a lookup table or calibration curve may be used to determine the concentration of the second analyte.

[0191] The active area of ​​the alcohol sensor may be based, for example, on X7-wired diaphorase coupled to ketone reductase (KRED) by freely diffusing nicotinamide-adenine dinucleotide phosphate (NADP) trapped within the sensing layer. Such an active area may be a good example of low enzyme activity, which can improve the sensor performance. Low enzyme activity may be, for example, about 10 to about 10,000 times lower activity than a normally working analyte sensor. For active areas with low enzyme activity, the inherent thermal stability of the enzyme may have an increasingly important effect on the rendered signal. For example, under low enzyme activity conditions, it may be difficult to compensate for the enzyme instability by increasing the enzyme loading. This makes it difficult to achieve a stable sensitivity (ratio of current to alcohol concentration) over the sensor's implantation period and / or during the sensor's shelf life. A stable sensitivity can be achieved, for example, by increasing the enzyme's thermal stability and / or by the use of a membrane-limited sensor. The use of the proposed peak width measurement can enable alcohol quantification using data from the sensor, despite the difficulty in achieving a stable sensitivity. The implantation period can be hours, days, weeks, or months. For example, the implantation period can range from 2 hours to 14 days.

[0192] 21A and 21B are graphs showing the current output of an exemplary analyte sensor embodied herein. FIG. 21A and FIG. 21B show the same current output, but FIG. 21A shows the current output from day 1 (9 / 21) to day 14 (10 / 5), and FIG. 21B focuses on the current output from day 7 (9 / 27) to day 12 (10 / 2). The analyte sensor may be, for example, an ethanol sensor 2102. FIG. 21A shows the current output 2104 of the ethanol sensor 2102 over a two-week period. Over the first five days of wearing the ethanol sensor 2102, the individual wearing the sensor consumed various amounts and concentrations of alcoholic beverages, each time producing a discernible peak in the signal output generated by the alcohol sensor. The peak may be defined by a peak height or a peak amplitude, which are used interchangeably herein. The peak signal output may be, for example, a current, a voltage, a charge, an energy, a potential, a potential difference, or any other signal output. For example, on day 1 (9 / 21), the individual consumed 24 ounces of beer with a 7% alcohol content. The corresponding current output was about 5200 picoamps. On day 2 (9 / 22), the individual consumed 24 ounces of beer with a 5% alcohol content, and on day 3 (9 / 23), the individual consumed 24 ounces of beer with a 7% alcohol content. The corresponding current outputs were about 5100 picoamps and about 3700 picoamps, respectively. On day 4 (9 / 24), the individual wearing the sensor consumed no alcohol, and on day 5 (9 / 25), the individual consumed 16 ounces of beer with a 7% alcohol content. The corresponding current output on day 5 was about 3200 picoamps.

[0193] For the remainder of days 6-14 (9 / 26-10 / 5), the individual consumed approximately 340 g (12 oz) of beer with an alcohol content of 7% each day, except for day 12, when no alcohol was consumed. While the amount and content of alcohol remained consistent between days 6-14, the current output changed from approximately 2800 picoamps on day 6 to approximately 1100 picoamps on day 14. As shown, the current output steadily decreased or decayed from day 6 to day 14. This decay can be seen not only in FIG. 21A, but also in the current output shown in FIG. 22 (after subtraction of background current not attributable to alcohol consumption).

[0194] FIG. 22 is a graph showing the current output of an exemplary analyte sensor embodied herein. As shown in FIG. 22, the peak current height 2202 of the alcohol sensor is the same as the peak current heights from days 6 to 14 in FIG. 21A, with the threshold or background signal level subtracted or removed. The threshold or background signal level may also be referred to as the noise level. An exemplary threshold or background signal level 2106 is shown in FIG. 21A. As shown in FIG. 21A, the threshold or background signal level trend is about 1000 picoamps from days 1 to 3, and then decreases linearly to about 500 picoamps on day 14. The threshold or background signal level may, for example, decrease either linearly or nonlinearly during at least a portion of the life of the analyte sensor. The threshold or background signal level may, for example, decrease either linearly or nonlinearly during at least a portion of the life of the analyte sensor. The threshold or background signal level may stabilize or equilibrate after an initial wearing period. The initial wearing period can be, for example, 2 days, 3 days, 4 days, 5 days, 6 days, or 7 days. The threshold or background signal level can correspond, for example, to the charge passed in an electrochemical assay in the absence of analyte.

[0195] As shown in FIG. 22, the peak height and area decay over a 9-day period during which the individual consumed a consistent amount of alcohol. For example, on day 6, the peak height is about 1700 picoamps, and on day 14, the peak height is about 550 picoamps. However, the peak height of the current output reaches a low of 400 picoamps on day 13. Thus, the overall decrease in peak height from the highest to the lowest value may be about 75%, which may occur when an individual consumes a consistent amount of alcohol every day, as embodied herein. The decay may be caused, at least in part, by the degradation of the enzymes in the active area on the alcohol sensor. In FIG. 21A, the peak height on day 13 appears higher than on day 14, while in FIG. 22, the peak height on day 13 appears lower than on day 14. The lower peak height on day 13 in FIG. 22 may be the result of a higher threshold or background signal level on day 13 than on day 14.

[0196] Determining blood alcohol concentration (BAC, also referred to as blood alcohol content) based on factors other than or in addition to peak height may improve the accuracy of such determination, at least in part due to the decay of peak height over time. For example, but not by way of limitation, as embodied herein, an analyte sensor may determine BAC by considering the width of a peak signal in a current signal over time. The width of the peak signal may be the amount of time that the signal exceeds a threshold signal level, background signal level, or noise level. The amount of time may be measured in minutes, hours, or days. The calculation of the peak signal may be performed in either the sensing system 100 or the reader device 120. For example, as shown in FIG. 21B, the width of the peak signal on day 10 (9 / 30) crosses the threshold or background signal level 2106 at time 2108 and time 2110. Thus, the width of the peak signal spans from time 2108 to time 2110 and may be approximately 2 hours and 15 minutes.

[0197] The width of the peak signal of the alcohol analyte measurement can be correlated with other aspects of alcohol metabolism. For example, the alcohol excretion rate (meaning the rate at which alcohol is metabolized or absorbed by the human body) can be constant for a given individual, which means that the rate can be independent of the amount of alcohol consumed. While other drugs may have an excretion rate that is proportional to the drug concentration and thus have a half-life excretion pattern, the alcohol metabolism or excretion rate can be considered to be independent of the amount of alcohol consumed. Therefore, the BAC decreases at a linear rate so that the width of the peak can be proportional to the peak.

[0198] FIG. 23 is a graph showing the current output of an exemplary analyte sensor embodied herein. For example, FIG. 23 shows a comparison of the width (in hours) 2304 of the peak in the current output of an alcohol sensor versus the height (in picoamps) 2302 of the peak. As shown in FIG. 23, the width 2304 of the peak begins at about 3 hours and decreases to about 2 hours, which is approximately a 33% decay. Meanwhile, the height 2302 of the peak begins at a peak of about 1800 picoamps and decreases to about 400 picoamps, which is approximately a 75% decay. Thus, the BAC can be determined by considering the width of the peak signal. Additionally, for purposes of example only and not limitation, the amplitude of the peak may be used in combination with the width of the peak to determine the BAC.

[0199] As discussed herein, alcohol excretion rates may vary between individuals. The relationship between peak width and BAC may also vary between individuals. For example, BAC determinations can be adjusted for such variations by combining peak width information with peak amplitude information during a calibration period, which may be, for example, but is not limited to, an initial wear period. For example, an individual's peak width and amplitude may be measured during the first 10 days, 6 days, 5 days, 4 days, 3 days, 2 days, or 1 day of a wear period. An individual's peak width and amplitude may be measured within the first 24-hour wear period, for example, within the first 12 hours, 6 hours, 3 hours, 2 hours, or 1 hour. By capturing data during the initial wear period, the individual's peak signal width and amplitude can be captured while minimizing or eliminating the effect of enzyme degradation on the measured peak width and amplitude. These peak signal widths and / or peak signal amplitudes measured during the initial wear period may be referred to as initial peak signal widths or initial peak signal amplitudes.

[0200] For example, the BAC can be determined using the following formula:

[0201]

number

[0202] where BAC is the blood alcohol concentration, K1 is the factory sensitivity of the alcohol sensor determined from calibration, and i peakis the peak signal. Calibration of the alcohol sensor may be performed during the manufacturing or design stage of the alcohol sensor. For example, the calibration may be a beaker calibration. The factory sensitivity may be, for example, a predetermined number or coefficient associated with a given manufacturing batch or alcohol sensor. An individual wearing an alcohol sensor may input an identification or code associated with the alcohol sensor into a reader device, and the factory sensitivity corresponding to that alcohol sensor may be applied to the signal generated by the alcohol sensor. Alternatively, the factory sensitivity may be programmed into the alcohol sensor itself without further input from the wearer or another user. Thus, the blood alcohol concentration determination may be adjusted based on the sensitivity of each individual alcohol sensor or manufacturing batch of alcohol sensors, by way of example and not limitation.

[0203] As embodied herein, the peak signal may be determined based on the following equation:

[0204]

number

[0205] where K2 is the ratio of the height or amplitude of the peak signal to the width of the peak signal, and i peak is the peak signal, and Width peak Once K1 and K2 have been determined during the initial wearing period, the BAC of subsequent peaks, including those resulting from enzyme degradation in the alcohol sensor, can be determined using the following equation:

[0206]

number

[0207] A BAC determined based on K1 and K2, rather than relying solely on peak signal amplitude, can result in improved and more stable BAC levels. Thus, the blood alcohol concentration can be determined based in part on the width of the peak signal. The blood alcohol concentration may be determined based on the ratio of the amplitude of the peak signal to the width of the peak signal.

[0208] FIG. 24 is a graph showing the current output of two exemplary analyte sensors embodied herein worn simultaneously. FIG. 24 shows the current output of the two sensors from day 1 (3 / 28) to day 15 (4 / 11), as well as the corresponding blood alcohol concentration (BAC). The analyte sensors may be, for example, two ethanol sensors 2102. FIG. 24 shows the current output S3-1 of the first ethanol sensor and the current output S3-2 of the second ethanol sensor over a 15-day period. As shown in FIG. 24, the outputs S3-1 and S3-2 show a consistent pattern in the detection of alcohol. During the wearing period of the two ethanol sensors, the individual wearing the sensors consumed various amounts of alcoholic beverages, each time producing a discernible peak in the signal output. This peak may be defined by the peak height or the peak amplitude, which are used interchangeably herein. The peak signal output may be, for example, a current, a voltage, a charge, an energy, a potential, a potential difference, or any other signal output. For purposes of illustration and not limitation, on day 1 (3 / 28), the individual had a total alcohol intake of approximately 0.98 oz. The corresponding current output peak 2405 was approximately 3488 picoamps. The corresponding blood alcohol concentration (BAC) is approximately 0.046%. For purposes of illustration, the width of the corresponding peak signal measured at half-height of the peak is 122 minutes. On day 5 (4 / 1), the individual had a total alcohol intake of approximately 0.98 oz. The corresponding current output peak 2410 was approximately 2390 picoamps. The corresponding blood alcohol concentration (BAC) is approximately 0.043%. The width of the corresponding peak signal is 138 minutes. On day 8 (4 / 1), the individual had a total alcohol intake of approximately 1.95 oz. The corresponding current output peak 2415 was approximately 3430 picoamps. The corresponding blood alcohol concentration (BAC) is approximately 0.057%. The corresponding peak signal width is 320 minutes. On day 12 (4 / 8), the individual had a total alcohol intake of approximately 23 g (0.82 oz). The corresponding current output peak 2420 was approximately 1339 picoamps. The corresponding blood alcohol concentration (BAC) is approximately 0.015%. The corresponding peak signal width is 80 minutes.On day 14 (4 / 10), the individual had a total alcohol intake of approximately 42 g (1.48 oz). The corresponding current output peak 2425 was approximately 2650 picoamps. The corresponding blood alcohol concentration (BAC) is approximately 0.051%. The corresponding peak signal width is 215 minutes.

[0209] 25 illustrates the correlation between the BAC measured at a signal peak and the width of the corresponding current peak. For illustrative purposes and not for limitation, a linear regression line 2505 is generated based on the exemplary data points described above. For example, as described above, the BAC of subsequent peaks, including peaks resulting from enzyme degradation of the alcohol sensor, can be determined using the following formula:

[0210]

number

[0211] 26 illustrates the correlation between total alcohol consumption measured at the signal peak and the width of the corresponding current peak. For purposes of illustration and not limitation, a linear regression line 1005 is generated based on the exemplary data points described above. For example, as described above, total alcohol consumption (TAC) and the width of the peak are linearly correlated. As embodied herein, total alcohol consumption can be determined using the following formula:

[0212]

number

[0213] where K3 can be a predetermined coefficient. For purposes of example only and not limitation, the alcohol sensor described herein may be used for a variety of purposes, including, but not limited to, individual health monitoring, enforcement or monitoring of compliance with alcohol-related rules or agreements, group therapy, and any other use for information regarding alcohol levels, which may refer to a BAC as described herein for a person or group. For example, but not limited to, the alcohol sensor may be used for self-monitoring by a user or remote monitoring by a caregiver or health care provider to enable a user to accurately monitor their alcohol intake over a period of time, for example, but not limited to, to assist a user in identifying unsafe amounts of alcohol consumption and / or controlling alcohol consumption to a desired amount. As embodied herein, the alcohol sensor may be worn for a desired period of time, which may be any of the wearing periods described herein, and the results may be reported to the user for analysis and / or to the user's health care provider for review prior to consultation.

[0214] As embodied herein, by way of example only, the alcohol sensor may be used to enforce compliance with alcohol-related conditions or restrictions of criminal parole, probation, or diversion programs by persons who are subject to alcohol-related conditions or restrictions. As embodied herein, the user's alcohol level may be transmitted to parole, probation, or diversion officials, or other monitoring entities responsible for enforcing compliance with the terms of such programs. Additionally or alternatively, as embodied herein, the alcohol sensor may be used to enforce compliance with occupational or workplace rules or regulations involving alcohol, such as safety rules and regulations involving the use of alcohol during or before the operation of a truck or other motor vehicle, machinery, or other heavy equipment, and may communicate the employee's alcohol level to an employer or other entity responsible for monitoring compliance with such rules or regulations. Additionally, as embodied herein, an alcohol sensor may be used to activate or deactivate an external device, such as an automobile, machine, or other heavy machinery, which may be activated when the alcohol sensor is used to determine that the user's alcohol level is sufficiently low for safe operation by the user, and / or may be locked or deactivated when the alcohol sensor indicates that the user's alcohol level is unsafe for operation of the external device.

[0215] Additionally or as a further alternative, the alcohol sensor may be used for group support for alcohol cessation. Members of the support group, which may be a formal or informal group of people interested in achieving or maintaining cessation of alcohol consumption, may each wear an alcohol sensor and agree to share alcohol sensor information with each other member of the support group, for example, via the cloud-based system and monitoring application described herein. The alcohol sensor information may include the user's alcohol level and the status of the alcohol sensor, such as active or working. Sharing the alcohol sensor information with the support group may encourage users to remain alcohol-free through peer support and may notify the support group when encouragement or intervention with members should be provided.

[0216] According to other aspects of the disclosed subject matter, the alcohol sensor can be used to provide a user with personalized insights based on alcohol level data. By way of example and not limitation, as embodied herein, the alcohol level data may be correlated with the amount of dehydration of the user caused by alcohol intake. The alcohol level data may be used to determine the user's BAC over time, for example, using measurements of the width of analyte level peaks over time, as described herein. As embodied herein, the user's BAC over time may be correlated with the amount of dehydration of the user, for example, by the data reading device 120 or the multi-purpose data receiving device 130. The data reading device 120 or the multi-purpose data receiving device 130 may be configured to provide recommendations based on the amount of dehydration of the user determined from the alcohol level data. By way of example only and not limitation, the data reading device 120 or the multi-purpose data receiving device 130 may be configured to recommend to the user to consume a particular amount of oral electrolyte solution (e.g., Pedialyte® by Abbott Laboratories) based on the amount of dehydration determined. Such insight may be provided in combination with other data, including data from other analyte sensors. For example, but not by way of limitation, as embodied herein, a dual alcohol-ketone sensor can provide additional insight related to alcohol consumption. For example, a ketogenic diet may increase a person's BAC faster, and thus a data reading device 120 or a general-purpose data receiving device 130 in communication with a dual alcohol-ketone sensor (or separate alcohol and ketone sensors) can provide an indication to a user when the user's ketone analyte level or ketosis level is at risk of or increasing the user's BAC faster than when not in ketosis or at a lower ketone level.

[0217] While the disclosed subject matter has been described herein with reference to certain preferred embodiments for purposes of illustration and not limitation, those skilled in the art will recognize that various modifications and improvements can be made to the disclosed subject matter without departing from its scope. Moreover, while individual features of one embodiment of the disclosed subject matter may be described herein or shown in drawings of one embodiment rather than other embodiments, it should be readily apparent that individual features of one embodiment may be combined with one or more features of another embodiment or features from multiple embodiments.

[0218] In addition to the specific embodiments claimed below, the disclosed subject matter is also directed to other embodiments having any other possible combinations of the dependent features claimed below and the dependent features disclosed above. Thus, the specific features presented in the dependent claims and disclosed above can be combined with each other in other possible combinations. Thus, the foregoing description of specific embodiments of the disclosed subject matter has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosed subject matter to the disclosed embodiments.

[0219] It will be apparent to those skilled in the art that various modifications and variations can be made in the methods and systems of the disclosed subject matter without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter includes modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. A system for detecting an alcohol level, comprising: a sensor control device; and a data receiving device in communication with the sensor control device, The sensor control device includes: an in-vivo alcohol sensor comprising a portion disposed in contact with a bodily fluid and configured to detect alcohol in the bodily fluid; and sensor electronics coupled to the in-vivo alcohol sensor. The data receiving device is A communication module; A display and one or more processors; a memory coupled to the one or more processors for storing instructions; The instructions, when executed by the one or more processors, cause the one or more processors to receiving a signal from the sensor control device; determining a peak signal width of the received signal, the period during which the signal exceeds a background or threshold level of the signal; and The system determines a total amount of alcohol consumed based on the width of the peak signal.

2. The system described in claim 1, wherein the width of the peak signal is linearly correlated with the total amount of alcohol consumed.

3. The system of claim 1, wherein the total amount of alcohol consumed is determined based on the formula TAC = K3 x peak width, where TAC is the total amount of alcohol consumed, K3 is a predetermined coefficient, and peak width is the width of the peak signal.

4. The system described in claim 1, wherein the in-vivo alcohol sensor comprises at least one electrode.

5. The system described in claim 4, wherein the in vivo alcohol sensor has an active area containing an enzyme to facilitate detection of alcohol.

6. The system described in claim 5, wherein the in vivo alcohol sensor has an active area for detecting a second analyte.

7. The system described in claim 1, wherein the data receiving device comprises a display configured to output information corresponding to the detection of an alcohol level.

8. The system described in claim 1, wherein the in-vivo alcohol sensor is calibrated at the factory.

9. The system described in claim 1, wherein the data receiving device is a smartphone.

10. The system of claim 1, wherein the one or more processors are further configured to determine a blood alcohol concentration based in part on a width of the peak signal.

11. Receiving a signal by a data receiving device from a sensor control device comprising an in-vivo alcohol sensor having a portion disposed in contact with a bodily fluid to detect alcohol in the bodily fluid, and sensor electronics coupled to the in-vivo alcohol sensor; determining, by the data receiving device, a peak signal width of the received signal, the period during which the signal exceeds a background or threshold level of the signal; determining, by the data receiving device, a total amount of alcohol consumed based on a width of the peak signal; 16. A method for detecting an alcohol level, comprising:

12. The method of claim 11, wherein the width of the peak signal is linearly correlated with the total amount of alcohol consumed.

13. The method of claim 11, wherein the total amount of alcohol consumed is determined based on the formula TAC = K3 x peak width, where TAC is the total amount of alcohol consumed, K3 is a predetermined coefficient, and peak width is the width of the peak signal.

14. The method of claim 11, wherein the in-vivo alcohol sensor comprises at least one electrode.

15. The method of claim 14, wherein the in vivo alcohol sensor has an active area containing an enzyme to facilitate detection of alcohol.

16. The method of claim 15, wherein the in-vivo alcohol sensor has an active area for detecting a second analyte.

17. The method of claim 11, wherein the data receiving device comprises a display configured to output information corresponding to the detection of an alcohol level.

18. The method of claim 11, wherein the in-vivo alcohol sensor is calibrated at a factory.

19. The method of claim 11, wherein the data receiving device is a smartphone.

20. The method of claim 11, further comprising determining a blood alcohol concentration based in part on a width of the peak signal.

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