Analyte Sensor Deployment Testing

Abstract

Various embodiments are directed to systems and methods that may utilize an analyte sensor system that includes a sensor housing, an analyte sensor extending from the sensor housing, and sensor electronics positioned within the sensor housing. The sensor electronics may be configured to detect when a wireless signal changes from a first state to a second state, and the wireless signal may be provided through the sensor housing. After detecting when the wireless signal changes from the first state to the second state, the sensor electronics may monitor whether the wireless signal remains in the second state for at least a stability threshold time period. The sensor electronics may perform a response action in the sensor system based at least in part on whether the wireless signal remains in the second state for at least a stability threshold time period.

Description

[Technical field]

[0001] Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 265,665, filed December 17, 2021, which is incorporated herein by reference in its entirety.

[0002] The present development relates generally to medical devices such as analyte sensors, and more particularly, but not by way of limitation, to systems, devices and methods for testing analyte sensor deployments. [Background technology]

[0003] Diabetes is a metabolic disease linked to the body's production or use of insulin, a hormone that allows the body to use glucose for energy or store it as fat.

[0004] When a human eats a meal containing carbohydrates, the food is processed by the digestive system, producing glucose in the blood. Blood glucose can be used as energy or stored as fat. The body normally maintains blood glucose levels in a range that provides enough energy to support bodily functions and avoids problems that can result from glucose levels that are too high or too low. Regulation of blood glucose levels depends on the production and use of insulin, which regulates the movement of blood glucose into cells.

[0005] When the body does not produce enough insulin or is unable to effectively use the insulin that is present, blood glucose levels can rise above the normal range. A condition in which blood glucose levels are higher than normal is called "hyperglycemia." Chronic hyperglycemia can lead to many health problems, including cardiovascular disease, cataracts and other eye diseases, nerve damage (neuropathy), and kidney damage. Hyperglycemia can also lead to acute problems, such as diabetic ketoacidosis (a condition in which the body becomes too acidic due to the presence of glucose in the blood and ketone bodies, which are produced when the body can no longer use glucose). A condition in which blood glucose levels are lower than normal is called "hypoglycemia." Severe hypoglycemia can lead to acute crises that can result in seizures or death.

[0006] Diabetic patients may receive insulin to manage blood glucose levels. Insulin may be received, for example, through a manual injection with a needle. Wearable insulin pumps are also available. Diet and exercise also affect blood glucose levels. Glucose sensors provide estimated glucose concentration levels and can be used as guidance by the patient or caregiver.

[0007] Diabetes is sometimes referred to as "Type 1" and "Type 2". Type 1 diabetes patients are typically able to use insulin when it is present, but due to problems with the insulin-producing beta cells of the pancreas, the body is unable to produce sufficient amounts of insulin. Type 2 diabetes patients are able to produce some insulin, but due to reduced sensitivity to insulin, the patient is "insulin resistant". As a result, even though insulin is present in the body, the insulin is not used well by the patient's body and does not effectively regulate blood glucose levels.

[0008] Blood glucose concentration levels can be monitored with an analyte sensor, such as a continuous glucose monitor, that is used by a host (e.g., a patient) to provide information such as an estimated blood glucose value or a trend in an estimated blood glucose level. Summary of the Invention [Problem to be solved by the invention]

[0009] The present application discloses, among other things, systems, devices, and methods relating to analyte sensors, including, for example, deployment tests in analyte sensors. [Means for solving the problem]

[0010] Example 1 is a sensor system for in vivo use comprising a sensor housing, an analyte sensor extending from the sensor housing, and sensor electronics positioned within the sensor housing, the electronics configured to perform operations including: detecting a wireless signal, the wireless signal provided through the sensor housing, that changes from a first state to a second state; monitoring whether the wireless signal remains in the second state for at least a stability threshold time period after detecting that the wireless signal has changed from the first state to the second state; and performing an action in the sensor system selected based at least in part on whether the wireless signal remains in the second state for at least a stability threshold time period.

[0011] In Example 2, the subject matter of Example 1 optionally includes an applicator for inserting the analyte sensor under the skin of the host, the applicator comprising a transmitter, the transmitter generating a wireless signal.

[0012] In Example 3, the subject matter of Examples 1 or 2 optionally includes a wireless signal sensor, the wireless signal sensor including at least one of a magnetic signal sensor, an inductive signal sensor, or an optical signal sensor.

[0013] In Example 4, the subject matter of any one or more of Examples 1-3 optionally includes detecting a change in the wireless signal from a first state to a second state, where the detecting includes: determining that the wireless signal is at least partially in the first state at a first time by determining that the wireless signal is present; and determining that the wireless signal is at least partially in the second state at a second time by determining that the wireless signal is not present, where the second time is after the first time.

[0014] In Example 5, the subject matter of any one or more of Examples 1-4 optionally includes detecting a change in the wireless signal from a first state to a second state, where the detecting includes: determining that, at a first time, the wireless signal is at least partially in the first state by determining that the wireless signal has a first magnetic polarity, and determining that, at a second time, the wireless signal is at least partially in the second state by determining that the wireless signal has a second magnetic polarity, different from the first magnetic polarity, where the second time is after the first time.

[0015] In Example 6, the subject matter of any one or more of Examples 1-5 optionally includes determining whether the wireless signal remains in the second state for at least a stability threshold time period, where determining includes determining that the wireless signal remains in the second state for at least a stability threshold time period, and the action includes determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0016] In Example 7, the subject matter of any one or more of Examples 1-6 optionally includes an operation, the operation further including determining that the sensor electronics have established a communication connection with the external device before the wireless signal remains in the second state for at least the stability threshold time period, and the action including determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0017] In Example 8, the subject matter of any one or more of Examples 1-7 optionally includes an operation, the operation further including, after detecting that the wireless signal has changed from the first state to the second state, determining that the wireless signal has remained in the first state for more than a stability threshold time period, and the action including configuring the sensor system into a sleep mode.

[0018] In Example 9, the subject matter of any one or more of Examples 1-8 optionally includes an operation, the operation further including determining that an activation time period has elapsed since detecting that the wireless signal has changed from the first state to the second state.

[0019] In Example 10, the subject matter of any one or more of Examples 1-9 optionally includes an operation, the operation further including determining that more than a failure threshold time period has elapsed since detecting that the wireless signal has changed from a first state to a second state, the failure threshold time period being greater than the stability threshold time period.

[0020] In Example 11, the subject matter of any one or more of Examples 1-10 optionally includes an action, the action further including determining that an activation threshold time period has elapsed since detecting that the wireless signal has changed from a first state to a second state, and determining that the wireless signal has remained in the first state for more than a stability threshold time period, and the action includes configuring the sensor system to a fail state.

[0021] In Example 12, the subject matter of any one or more of Examples 1-11 optionally includes operations, the operations further including determining that a wake-up threshold time period has elapsed since detecting a change in the wireless signal from a first state to a second state and determining that the wireless signal has not remained in either the first state or the second state for more than a stability threshold time period, and initiating a communication connection with an external device.

[0022] In Example 13, the subject matter of Example 12 optionally includes an operation, the operation further including determining that the sensor electronics have established a communication connection with the external device, and the action including determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0023] In Example 14, the subject matter of any one or more of Examples 1-13 optionally includes an operation, the operation further including determining that a sensor output generated by the analyte sensor satisfies a first insertion condition.

[0024] In Example 15, the subject matter of Example 14 optionally includes operations, the operations further including initiating a communication connection with the external device after determining that the sensor output satisfies a first insertion condition, and determining that the sensor electronics have established a communication connection with the external device, and the actions including determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0025] Example 16 is a method for operating an analyte sensor system including an in vivo analyte sensor, the method including: detecting, by sensor electronics of the analyte sensor system, that a wireless signal, the wireless signal being provided to the sensor electronics through a sensor housing of the analyte sensor system, has changed from a first state to a second state; after detecting that the wireless signal has changed from the first state to the second state, monitoring, by the sensor electronics, whether the wireless signal remains in the second state for at least a stability threshold time period; and performing, by the sensor electronics, an action in the sensor system, the action being selected based at least in part on whether the wireless signal remains in the second state for at least a stability threshold time period.

[0026] In Example 17, the subject matter of Example 16 optionally includes receiving a wireless signal by the sensor electronics and from a transmitter, the transmitter being positioned in an applicator for inserting an analyte sensor of the analyte sensor system under the skin of a host.

[0027] In Example 18, the subject matter of any one or more of Examples 16-17 optionally includes receiving a wireless signal using at least one of a magnetic signal sensor, an inductive signal sensor, or an optical signal sensor.

[0028] In Example 19, the subject matter of any one or more of Examples 16-18 optionally includes detecting a change in the wireless signal from a first state to a second state, where the detecting includes: determining that the wireless signal is at least partially in the first state at a first time by determining that the wireless signal is present; and determining that the wireless signal is at least partially in the second state at a second time by determining that the wireless signal is not present, where the second time is after the first time.

[0029] In Example 20, the subject matter of any one or more of Examples 16-19 optionally includes detecting a change in the wireless signal from a first state to a second state, where the detecting includes: determining that, at a first time, the wireless signal is at least partially in the first state by determining that the wireless signal has a first magnetic polarity, and determining that, at a second time, the wireless signal is at least partially in the second state by determining that the wireless signal has a second magnetic polarity, different from the first magnetic polarity, where the second time is after the first time.

[0030] In Example 21, the subject matter of any one or more of Examples 16-20 optionally includes determining whether the wireless signal remains in the second state for at least a stability threshold time period, where determining includes determining that the wireless signal remains in the second state for at least a stability threshold time period, and the action includes determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0031] In Example 22, the subject matter of any one or more of Examples 16-21 optionally includes determining that the sensor electronics have established a communication connection with the external device before the wireless signal remains in the second state for at least the stability threshold time period, and the action includes determining an estimated analyte value for the host using a sensor output generated by the analyte sensor.

[0032] In Example 23, the subject matter of any one or more of Examples 16-22 optionally includes, after detecting that the wireless signal has changed from the first state to the second state, determining that the wireless signal has remained in the first state for more than a stability threshold time period, and the action includes configuring the sensor system into a sleep mode.

[0033] In Example 24, the subject matter of any one or more of Examples 16-23 optionally includes determining that an activation time period has elapsed since detecting that the wireless signal has changed from the first state to the second state.

[0034] In Example 25, the subject matter of any one or more of Examples 16-24 optionally includes determining that more than a failure threshold time period has elapsed since detecting that the wireless signal has changed from a first state to a second state, the failure threshold time period being greater than the stability threshold time period.

[0035] In Example 26, the subject matter of any one or more of Examples 16-25 optionally includes determining that an activation threshold time period has elapsed since detecting a change in the wireless signal from a first state to a second state, and determining that the wireless signal has remained in the first state for more than a stability threshold time period, and the action includes configuring the sensor system to a fail state.

[0036] In Example 27, the subject matter of any one or more of Examples 16-26 optionally includes determining that an activation threshold time period has elapsed since detecting a change in the wireless signal from a first state to a second state and determining that the wireless signal has not remained in either the first state or the second state for more than a stability threshold time period, and initiating a communication connection with an external device.

[0037] In Example 28, the subject matter of Example 27 optionally includes determining that the sensor electronics have established a communication connection with the external device, and the action includes determining an estimated analyte value for the host using a sensor output generated by the analyte sensor.

[0038] In Example 29, the subject matter of any one or more of Examples 16-28 optionally includes determining that a sensor output produced by the analyte sensor satisfies a first insertion condition.

[0039] In Example 30, the subject matter of Example 29 optionally includes initiating a communication connection with the external device after determining that the sensor output satisfies a first insertion condition, and determining that the sensor electronics have established a communication connection with the external device, wherein the action includes determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0040] Example 31 is a non-transitory machine-readable medium including instructions that, when executed by an analyte sensor system, cause the analyte sensor system to perform operations including detecting a wireless signal, the wireless signal being provided to sensor electronics of the analyte sensor system through a sensor housing of the analyte sensor system, that changes from a first state to a second state; monitoring whether the wireless signal remains in the second state for at least a stability threshold time period after detecting that the wireless signal has changed from the first state to the second state; and performing an action in the sensor system selected based at least in part on whether the wireless signal remains in the second state for at least a stability threshold time period.

[0041] In Example 32, the subject matter of Example 31 optionally includes an operation, the operation further including receiving a wireless signal from a transmitter, the transmitter being positioned in an applicator for inserting an analyte sensor of the analyte sensor system under the skin of a host.

[0042] In Example 33, the subject matter of Examples 31 or 32 optionally includes an operation, the operation further including receiving a wireless signal using at least one of a magnetic signal sensor, an inductive signal sensor, or an optical signal sensor.

[0043] In Example 34, the subject matter of any one or more of Examples 31-33 optionally includes detecting a change in the wireless signal from a first state to a second state, where the detecting includes: determining that the wireless signal is at least partially in the first state at a first time by determining that the wireless signal is present; and determining that the wireless signal is at least partially in the second state at a second time by determining that the wireless signal is not present, where the second time is after the first time.

[0044] In Example 35, the subject matter of any one or more of Examples 31-34 optionally includes detecting a change in the wireless signal from a first state to a second state, where the detecting includes: determining that, at a first time, the wireless signal is at least partially in the first state by determining that the wireless signal has a first magnetic polarity, and determining that, at a second time, the wireless signal is at least partially in the second state by determining that the wireless signal has a second magnetic polarity, different from the first magnetic polarity, where the second time is after the first time.

[0045] In Example 36, the subject matter of any one or more of Examples 31-35 optionally includes determining whether the wireless signal remains in the second state for at least a stability threshold time period including determining that the wireless signal remains in the second state for at least a stability threshold time period, and the action includes determining an estimated analyte value for the host using a sensor output generated by the analyte sensor.

[0046] In Example 37, the subject matter of any one or more of Examples 31-36 optionally includes an action, the action further including determining that the sensor electronics have established a communication connection with the external device before the wireless signal remains in the second state for at least the stability threshold time period, and the action including determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0047] In Example 38, the subject matter of any one or more of Examples 31 to 37 optionally includes an action, the action further including, after detecting that the wireless signal has changed from the first state to the second state, determining that the wireless signal has remained in the first state for more than a stability threshold time period, and the action includes configuring the sensor system into a sleep mode.

[0048] In Example 39, the subject matter of any one or more of Examples 31-38 optionally includes an operation, the operation further including determining that an activation time period has elapsed since detecting that the wireless signal has changed from the first state to the second state.

[0049] In Example 40, the subject matter of any one or more of Examples 31-39 optionally includes an operation, the operation further including determining that more than a failure threshold time period has elapsed since detecting that the wireless signal has changed from a first state to a second state, the failure threshold time period being greater than the stability threshold time period.

[0050] In Example 41, the subject matter of any one or more of Examples 31-40 optionally includes an action, the action further including determining that an activation threshold time period has elapsed since detecting that the wireless signal has changed from a first state to a second state, and determining that the wireless signal has remained in the first state for more than a stability threshold time period, and the action includes configuring the sensor system to a fail state.

[0051] In Example 42, the subject matter of any one or more of Examples 31 to 41 optionally includes operations, the operations further including determining that a wake-up threshold time period has elapsed since detecting a change in the wireless signal from a first state to a second state and determining that the wireless signal has not remained in either the first state or the second state for more than a stability threshold time period, and initiating a communication connection with an external device.

[0052] In Example 43, the subject matter of Example 42 optionally includes an operation, the operation further including determining that the sensor electronics have established a communication connection with the external device, and the action including determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0053] In Example 44, the subject matter of any one or more of Examples 31-43 optionally includes an operation, the operation further including determining that a sensor output generated by the analyte sensor satisfies a first insertion condition.

[0054] In Example 45, the subject matter of Example 44 optionally includes an action, the action further including initiating a communication connection with an external device after determining that the sensor output satisfies a first insertion condition, and determining that the sensor electronics have established a communication connection with the external device, and the action includes determining an estimated analyte value for the host using the sensor output generated by the analyte sensor.

[0055] This Summary is intended to provide an overview of the subject matter of this patent application. It is not intended to provide an exclusive or exhaustive description of the disclosure. The Detailed Description is included to provide further information about this patent application. Other aspects of the disclosure will be apparent to those of ordinary skill in the art upon reading and understanding the following Detailed Description and viewing the drawings that form a part hereof, each of which is not to be construed in a limiting sense. [Brief description of the drawings]

[0056] In the drawings, which are not necessarily drawn to scale, like numerals may describe like components in different figures. Like numerals with different letter suffixes may represent different instances of the like components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments described in the present document.

[0057] [Figure 1] FIG. 1 illustrates an example of an environment including an analyte sensor system. [Diagram 2] FIG. 2 illustrates an example of a medical device system including the analyte sensor system of FIG. 1. [Diagram 3] 1 is an illustration of an exemplary analyte sensor. [Figure 4] 1 is an illustration of another exemplary analyte sensor. [Diagram 5] FIG. 1 is a close-up view of an exemplary analyte sensor portion. [Figure 6] FIG. 5 is a cross-sectional view of the analyte sensor of FIGS. 3 and 4. [Figure 7] 1 is a schematic illustration of a circuit illustrating the behavior of an exemplary analyte sensor. [Figure 8] FIG. 2 is an exploded side view of one embodiment of a sensor applicator. [Figure 9A] 9 shows one embodiment of the needle and sensor of FIG. 8 loaded prior to sensor insertion. [Figure 9B] 1 shows one embodiment of a needle and sensor after the sensor has been inserted. [Figure 9C] 13 illustrates one embodiment of a sensor and needle during needle retraction. [Figure 9D] 13 illustrates one embodiment of a sensor remaining in the contact subassembly after needle retraction. [Figure 10] 10 is a perspective view of the sensor applicator and mounting unit of FIG. 9 according to one embodiment including a safety latch mechanism. [Figure 11] 13 illustrates another embodiment of an analyte sensor applicator. [Figure 12] FIG. 1 illustrates an embodiment of an analyte sensor system including an analyte sensor and sensor electronics. [Figure 13] 13 is a flow chart illustrating an embodiment of a process flow that may be performed by the sensor electronics of the sensor system of FIG. 12 to transition the sensor system from a sleep mode to an active mode. [Figure 14] 13 is a state diagram illustrating an example of a workflow that may be implemented by the sensor electronics of the sensor system of FIG. 12 to perform an insertion test. [Figure 15] FIG. 13 is a state diagram illustrating an example of a workflow that may be executed by the sensor electronics of the sensor system of FIG. 12 to perform a deployment test that tests the deployment of an analyte sensor using a wireless signal detected by the deployment sensor. [Figure 16]FIG. 2 is a state diagram illustrating an example workflow that may be performed by the sensor electronics to transition the sensor system from a sleep mode to an active mode. [Figure 17] FIG. 11 is a state diagram illustrating another example workflow that may be performed by the sensor electronics to transition the sensor system from a sleep mode to an active mode. [Figure 18] FIG. 1 is a block diagram illustrating the hardware architecture of a computing device, within which a set or sequence of instructions may be executed to cause the machine to perform any one of the embodiments of the methods discussed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] Various embodiments described herein are directed to analyte sensor systems and methods for using the analyte sensor systems. The analyte sensor system includes an analyte sensor that is placed in contact with a bodily fluid of a host to measure a concentration of an analyte, such as glucose, in the bodily fluid. In some embodiments, the analyte sensor is inserted into the host so as to contact the bodily fluid in vivo. In some embodiments, the analyte sensor is inserted subcutaneously to contact interstitial fluid beneath the skin of the host.

[0059] When the analyte sensor is exposed to an analyte in the host's bodily fluid, the analyte sensor generates a raw sensor signal indicative of the analyte concentration in the bodily fluid due to an electrochemical reaction between the analyte sensor and the analyte. For example, the analyte sensor may include two or more electrodes. The analyte sensor system control circuitry applies bias conditions to the electrodes. The bias condition may be, for example, a potential difference applied between a working electrode of the analyte sensor and a reference electrode of the analyte sensor. The bias condition promotes an electrochemical reaction between the analyte and the analyte sensor, causing a current to flow between the working electrode and at least one other analyte sensor electrode. The raw sensor signal may be a current and / or may be based on a current.

[0060] The control circuit uses the raw sensor signal to determine the estimated analyte value. In some embodiments, the control circuit is also programmed to output result data, which may include the estimated analyte value or other data. In some embodiments, the control circuit communicates the result data to one or more other external devices.

[0061] After manufacture, the analyte sensor system may be transported and stored prior to use by the host. During transport and storage, the analyte sensor system may be configured to operate in a sleep mode. In the sleep mode, the analyte sensor system is configured to minimize power usage, thereby conserving battery or other on-board power for when the sensor system is actively being used by the host. When the host is ready to use the analyte sensor, the host inserts the sensor in vivo, for example, as described herein. After the analyte sensor is positioned in vivo, the control circuitry may begin to operate the sensor in an active or measurement state. In the active or measurement state, the control circuitry may apply bias conditions to the analyte sensor and / or use raw sensor signals generated by the sensor to determine an estimated analyte value. In some examples, the control circuitry may also initiate a communication connection with one or more other external devices to provide result data to the one or more other external devices.

[0062] The control circuitry may then be configured to detect when the analyte sensor is inserted in vivo to transition the analyte sensor system from a sleep mode to an active mode. One exemplary method of detecting sensor insertion is to periodically monitor the sensor to detect the presence of a raw sensor signal, e.g., a signal determined to have one or more characteristics, conditions, and / or profiles. For example, the analyte sensor may generate some level of raw sensor signal upon insertion. The control circuitry may detect insertion by determining that the analyte sensor is generating a raw sensor signal that meets an insertion condition, e.g., a current greater than a threshold, for longer than a threshold time. However, in some examples, the analyte sensor may not begin generating a raw sensor signal sufficient to indicate in vivo insertion until some time after insertion has occurred, in some examples, more than two minutes or more. As a result, the control circuitry may not operate the analyte sensor system in an active mode until a portion of the initial sensor deployment period has elapsed. Also, in some examples, the raw sensor signal generated before the control circuitry applies the bias condition may not be sufficient to accurately detect insertion.

[0063] In some examples, the control circuitry is configured to detect insertion using a deployed sensor. The deployed sensor may generate a signal indicating when the sensor is deployed. However, using a deployed sensor may pose additional challenges. For example, the control circuitry of the analyte sensor may be enclosed within a sensor housing with the analyte sensor extending from the sensor housing. When the analyte sensor is inserted in vivo, the sensor housing may be positioned and adhered onto the surface of the host's skin as described herein. Thus, the sensor housing may be exposed to bodily fluids from beneath the skin and / or substances and fluids that may otherwise come into contact with the host's skin.

[0064] For at least these reasons, it may be desirable to seal the sensor housing. However, sealing the sensor housing may pose challenges when using mechanically deployed sensors, such as switches. For example, mechanically deployed sensors may extend through the housing, preventing and / or complicating sealing of the housing. Mechanically deployed sensors may also produce bounce artifacts in the raw sensor signal that can waste system power and extend the time to detect insertion.

[0065] Some embodiments described herein use a deployed sensor that receives a wireless signal transmitted through a sensor housing. The wireless signal can have a first state that indicates that the analyte sensor is not deployed. The first state may be referred to as a non-deployed state. The wireless signal can also have a second state that indicates that the analyte sensor is deployed. The second state may be referred to as a deployed state.

[0066] The wireless signal may be generated and / or transmitted by a transmitter. For example, the transmitter may be positioned in a sensor applicator for inserting the analyte sensor. Prior to insertion of the analyte sensor, the transmitter may provide the wireless signal in a non-deployed state. After the analyte sensor is deployed in vivo, the transmitter may change the wireless signal to a deployed state.

[0067] The sensor control circuitry can include a deployed sensor configured to receive a wireless signal. When the analyte sensor system is in a sleep mode, the sensor control circuitry can periodically poll the deployed sensor to determine a state of the wireless signal. When the wireless signal changes from a non-deployed state to a deployed state, the sensor control circuitry can begin operating the sensor system in an active mode.

[0068] Various types of wireless technologies may be used to implement the transmitter and the deployment sensor. In some embodiments, the transmitter is or includes a permanent magnet, a solenoid, or other device for generating a magnetic field. The receiver may be or include a solenoid, an inductor, or other device capable of detecting a magnetic field. The magnetic field may constitute all or part of the wireless signal. For example, a first state of the wireless signal may occur when the magnetic field has a first polarity, and a second state of the wireless signal may occur when the magnetic field has a second polarity different from the first polarity. In another embodiment, the first state of the wireless signal may be indicated by the presence of a magnetic field, and the second state is indicated by the absence (or relative absence) of the magnetic field. In another embodiment, the first state is indicated by the absence (or relative absence) of the magnetic field, and the second state is indicated by the presence of another magnetic field. Other wireless technologies that may be used to generate the wireless signal include, for example, optical transmitters and receivers, Radio Frequency Identification (RFID) transmitters and receivers, and the like.

[0069] However, using a wireless signal transmitter may create other challenges. For example, when the transmitter is included in an analyte sensor applicator, the transition of the transmitter between transmitting a non-deployed state of the wireless signal and transmitting a deployed state of the wireless signal may be affected by actions of the host or other user. For example, the host or other user may not always cleanly remove the applicator upon insertion of the analyte sensor. For example, the host or other user may wiggle the applicator and disconnect it from the sensor housing. Also, sometimes the host or other user may use the applicator to help secure the sensor housing to the host's skin. In some examples, these and similar actions may cause the transmitter to switch the wireless signal between a deployed and non-deployed state and / or cause the transmitter to settle to a non-deployed state even if the analyte sensor is actually inserted under the host's skin. Also, in some examples, the wireless signal is affected by other environmental signals, such as light in the environment, devices that generate electromagnetic fields, etc. This may cause the wireless signal to switch to a state that does not match the actual state of the analyte sensor.

[0070] In some embodiments, the control circuitry is configured to test the wireless signal to determine when the analyte sensor is inserted and the sensor system should be operated in an active mode.

[0071] 1 illustrates an example of an environment 100 that includes an analyte sensor system 102. The analyte sensor system 102 is coupled to a host 101, which may be a human patient. In some examples, the host has a temporary or permanent diabetic condition or other health condition for which analyte monitoring is useful.

[0072] The analyte sensor system 102 includes an analyte sensor 104. In some embodiments, the analyte sensor 104 is or includes a glucose sensor configured to measure a glucose concentration in the host 101. The analyte sensor 104 may be exposed to an analyte in the host 101 in any suitable manner. In some embodiments, the analyte sensor 104 is fully implantable under the skin of the host 101. In other embodiments, the analyte sensor 104 is wearable on the host 101's body (e.g., worn on the body but not under the skin). Also, in some embodiments, the analyte sensor 104 is a transcutaneous device (e.g., having a sensor that resides at least partially under or in the skin of the host). It should be understood that the devices and methods described herein may be applied to any device capable of detecting a concentration of an analyte, such as glucose, and providing an output signal representative of the concentration of the analyte.

[0073] In the embodiment of FIG. 1, the analyte sensor system 102 also includes sensor electronics 106. In some embodiments, the sensor electronics 106 and the analyte sensor 104 are provided in a single integrated housing (see FIG. 3). In other embodiments, the analyte sensor 104 and the sensor electronics 106 are provided as separate components or modules (see FIG. 4). For example, the analyte sensor system 102 may include a disposable (e.g., single-use) sensor attachment unit, which may include the analyte sensor 104, components for attaching the sensor 104 to a host (e.g., an adhesive pad), and / or attachment structure configured to receive a sensor electronics unit that includes some or all of the sensor electronics 106 shown in FIG. 2. The sensor electronics unit may be reusable.

[0074] The analyte sensor 104 may provide a raw sensor signal indicative of the concentration of the analyte in the host 101 using any known method, including invasive, minimally invasive, or non-invasive sensing techniques (e.g., optically stimulated fluorescence, microneedle, transdermal monitoring of glucose). The raw sensor signal may be converted into calibrated and / or filtered analyte concentration data that is used to provide a useful value of the analyte concentration (e.g., an estimated blood glucose concentration level) to a user, such as the host or a caretaker (e.g., a parent, relative, guardian, teacher, doctor, nurse, or any other individual interested in the health status of the host 101).

[0075] In some examples, the analyte sensor 104 is or includes a continuous glucose sensor. The continuous glucose sensor may be or include a subcutaneous, transcutaneous (e.g., transdermal), and / or intravascular device. In some embodiments, such a sensor or device may repeatedly (e.g., periodically or intermittently) analyze sensor data. The glucose sensor may use any glucose measurement method, such as enzymatic, chemical, physical, electrochemical, spectrophotometric, polarimetric, calorimetric, iontophoretic, radiometric, immunochemical, etc. In various examples, the analyte sensor system 102 may be or include a continuous glucose monitor sensor available from DexCom™ (e.g., DexCom G5™ sensor, DexCom G6™ sensor, DexCom G7™ sensor, or any variation thereof), Abbott™ (e.g., Libre™ sensor), or Medtronic™ (e.g., Enlite™ sensor).

[0076] In some embodiments, the analyte sensor 104 includes an implantable glucose sensor, such as those described with reference to U.S. Patent No. 6,001,067 and U.S. Patent Application Publication No. 2005 / 0027463(A1), which are incorporated by reference. In some embodiments, the analyte sensor 104 includes a transcutaneous glucose sensor, such as those described with reference to U.S. Patent Application Publication No. 2006 / 0020187(A1), which are incorporated by reference. In some embodiments, the analyte sensor 104 may be configured to be implanted in a host vessel or outside the body, as described, for example, in U.S. Patent Application Publication No. 2007 / 0027385(A1), co-pending U.S. Patent Application Publication No. 2008 / 0119703(A1), filed October 4, 2006, U.S. Patent Application Publication No. 2008 / 0108942(A1), filed March 26, 2007, and U.S. Patent Application Publication No. 2007 / 0197890(A1), filed February 14, 2007, all of which are incorporated by reference. In some embodiments, the continuous glucose sensor may include a transcutaneous sensor, such as that described in U.S. Patent No. 6,565,509 to Say et al., which is incorporated by reference. In some examples, the analyte sensor 104 may include a continuous glucose sensor, including a subcutaneous sensor, such as those described with reference to U.S. Patent No. 6,579,690 to Bonnecaze et al., or U.S. Patent No. 6,484,046 to Say et al., which are incorporated by reference. In some examples, the continuous glucose sensor may include a refillable subcutaneous sensor, such as those described with reference to U.S. Patent No. 6,512,939 to Colvin et al., which are incorporated by reference. The continuous glucose sensor may include an intravascular sensor, such as those described with reference to U.S. Patent No. 6,477,395 to Schulman et al., which are incorporated by reference. The continuous glucose sensor may include an intravascular sensor, such as those described with reference to U.S. Patent No. 6,424,847 to Mastrototaro et al., which are incorporated by reference.

[0077] The environment 100 may also include various other external devices, including, for example, a medical device 108. The medical device 108 may be or may include a drug delivery device, such as an insulin pump or an insulin pen. In some examples, the medical device 108 includes one or more sensors, such as another analyte sensor, a heart rate sensor, a respiration sensor, a motion sensor (e.g., an accelerometer), a posture sensor (e.g., a three-axis accelerometer), an acoustic sensor (e.g., to capture ambient or internal sounds), etc. The medical device 108 may be, for example, wearable in a watch, glasses, contact lenses, a patch, a wristband, an ankle band, or another wearable item, or may be incorporated into a handheld device (e.g., a smartphone). In some examples, the medical device 108 includes a multi-sensor patch that can detect, for example, one or more of an analyte level (e.g., glucose, lactate, insulin, or other substance), heart rate, respiration (e.g., using impedance), activity (e.g., using an accelerometer), posture (e.g., using an accelerometer), galvanic skin response, tissue fluid levels (e.g., using impedance or pressure).

[0078] In some examples, the analyte sensor system 102 and the medical device 108 communicate with each other. Communication between the analyte sensor system 102 and the medical device 108 can occur via any suitable wired connection and / or via wireless communication signals 110. For example, the analyte sensor system 102 (e.g., its sensor electronics 106) can be configured to establish a communication connection with the medical device 108 using a suitable short-range communication medium, such as, for example, a radio frequency medium (e.g., Bluetooth, Medical Implant Communication System (MICS), Wi-Fi, near field communication (NFC), radio frequency identification (RFID), Zigbee, Z-Wave, or other communication protocol), an optical medium (e.g., infrared), an acoustic medium (e.g., ultrasound), a cellular protocol-based medium (e.g., Code Division Multiple Access (CDMA) or Global System for Mobiles (GSM)), and / or the like.

[0079] In some examples, the environment 100 also includes other external devices, such as, for example, a wearable sensor 130. The wearable sensor 130 may include a sensor circuit (e.g., a sensor circuit configured to detect a glucose concentration or other analyte concentration) and a communication circuit (which may be, for example, an NFC circuit). In some examples, information from the wearable sensor 130 may be obtained from the wearable sensor 130 using a user computing device 132, such as a smartphone, configured to communicate with the wearable sensor 130 via the communication circuit of the wearable sensor when the user device 132 is placed in proximity to the wearable sensor 130. For example, swiping the user device 132 over the sensor 130 may obtain sensor data from the wearable sensor 130 using NFC or other suitable wireless communication.

[0080] The use of NFC communication can reduce power consumption by the wearable sensor 130, reduce the size of the power source (e.g., a battery or capacitor) in the wearable sensor 130, or extend the usable life of the power source. In some examples, the wearable sensor 130 can be wearable on the upper arm, as shown. In some examples, the wearable sensor 130 can additionally or alternatively be on the patient's upper torso (e.g., above the heart or above the lungs), which can facilitate detection of, for example, heart rate, respiration, or posture. The wearable sensor 136 can also be on the lower body (e.g., legs) or other parts of the body (e.g., abdomen).

[0081] In some examples, an array or network of sensors may be associated with the patient. For example, the analyte sensor system 102 and / or one or more of the medical device 108, the wearable device 120, such as a wristwatch, and an external device, such as the additional wearable sensor 130, may communicate with each other via a short-range communication medium (e.g., Bluetooth, MICS, NFC, or any of the other options described above). The additional wearable sensor 130 may be any of the examples described above with respect to the medical device 108. The analyte sensor system 102, the medical device 108, and the additional sensor 130 on the host 101 are provided for purposes of illustration and description and are not necessarily drawn to scale.

[0082] The environment 100 may also include one or more other external devices, such as a handheld smart device (e.g., a smartphone) 112, a tablet 114, a smart pen 116 (e.g., an insulin delivery pen with processing and communication capabilities), a computer 118, a wearable device 120 such as a wristwatch, or a peripheral medical device 122 (which may be a proprietary device such as a proprietary user device available from DexCom), any of which may communicate with the analyte sensor system 102 via a short-range communication medium as indicated by the wireless communication signal 110, and may also communicate with a server system (e.g., a remote data center) or remote terminal 128 via a network 124 to facilitate communication with a remote user (not shown), such as a technical support staff member or a clinician.

[0083] The wearable device 120 may include an activity sensor, a heart rate monitor (e.g., an optical or electrode-based sensor), a respiration sensor (e.g., an acoustic or electrode-based sensor), a location sensor (e.g., GPS), or other sensors.

[0084] In some examples, environment 100 includes a server system 126. Server system 126 may include one or more computing devices, such as one or more server computing devices. In some examples, server system 126 is used to collect analyte data from analyte sensor system 102 and / or analyte or other data from multiple other devices, perform analyses on the collected data, generate or apply universal or individualized models for glucose levels, and communicate such analyses, models, or information based thereon back to one or more devices in environment 100. In some examples, server system 126 collects inter-host and / or intra-host break-in data and generates one or more break-in characteristics, as described herein.

[0085] The environment 100 may also include a wireless access point (WAP) 138 that is used to communicatively couple one or more of the analyte sensor system 102, the network 124, the server system 126, the medical device 108, or any of the peripheral devices mentioned above. For example, the WAP 138 may provide Wi-Fi and / or cellular connectivity within the environment 100. Other communication protocols, such as NFC or Bluetooth, may also be used between devices in the environment 100.

[0086] 2 illustrates an example of a medical device system 200 including the analyte sensor system 102 of FIG. 1. In the example of FIG. 2, the analyte sensor system 102 includes the sensor electronics 106 and an exemplary sensor mounting unit 290, although it will be understood that in some examples, the analyte sensor 104 and the sensor electronics 106 may be included within a common housing. Although specific examples of the division of components between the sensor mounting unit 290 and the sensor electronics 106 are shown, it will be understood that in some examples, the sensor mounting unit 290 or the sensor electronics 106 may include additional components, and that some of the components shown in the sensor electronics 106 (e.g., a battery or supercapacitor) may be alternatively or additionally (e.g., redundantly) provided in the sensor mounting unit 290.

[0087] 2, the sensor mounting unit 290 includes the analyte sensor 104 and a battery 292. In some embodiments, the sensor mounting unit 290 may be replaceable and the sensor electronics 106 may include debounce circuitry (e.g., a gate with hysteresis or delay) to, for example, avoid repeated power-up or power-down processes when repeatedly connected and disconnected, or to avoid processing noisy signals associated with removing or replacing a battery.

[0088] The sensor electronics 106 may include electronic components configured to process sensor information, such as raw sensor signals, to generate corresponding analyte concentration values. The sensor electronics 106 may include electronic circuitry associated with measuring, processing, storing, or communicating continuous analyte sensor data, including, for example, predictive algorithms associated with processing and calibrating raw sensor signals. The sensor electronics 106 may include hardware, firmware, and / or software that enable the measurement of analyte levels via the glucose sensor. The electronic components may be affixed to a printed circuit board (PCB) or the like and may take a variety of forms. For example, the electronic components may take the form of an integrated circuit (IC), such as an Application-Specific Integrated Circuit (ASIC), a microcontroller, and / or a processor.

[0089] In the example of FIG. 2, the sensor electronics 106 includes a measurement circuit 202 (e.g., a potentiostat) coupled to the analyte sensor 104 and configured to repeatedly obtain analyte sensor readings using the analyte sensor 104. For example, the measurement circuit 202 may continuously or repeatedly measure a raw sensor signal indicative of current flow in the analyte sensor 104 between a working electrode and a reference electrode. The sensor electronics 106 may include a gating circuit 294 that may be used to gate a connection between the measurement circuit 202 and the analyte sensor 104. For example, the analyte sensor 104 may accumulate charge over an accumulation period. After the accumulation period, the gating circuit 294 is opened to allow the measurement circuit 202 to measure the accumulated charge. Gating the analyte sensor 104 can improve the performance of the sensor system 102 by creating a greater signal-to-noise or interference ratio (e.g., because charge from the analyte reaction accumulates while interference sources, such as the presence of acetaminophen near the glucose sensor, do not accumulate or accumulate less than the charge from the analyte reaction).

[0090] The sensor electronics 106 may also include a processor 204. The processor 204 is configured to retrieve instructions 206 from the memory 208 and execute the instructions 206 to control various operations in the analyte sensor system 102. For example, the processor 204 may be programmed to control the application of a bias potential to the analyte sensor 104 via a potentiostat in the measurement circuit 202, interpret a raw sensor signal from the analyte sensor 104, and / or compensate for environmental factors.

[0091] The processor 204 can also store information in or retrieve information from the data storage memory 210. In various embodiments, the data storage memory 210 can be integrated with the memory 208 or can be a separate memory circuit, such as a non-volatile memory circuit (e.g., flash RAM). Examples of systems and methods for processing sensor analyte data are described in further detail herein and in U.S. Patent Nos. 7,310,544 and 6,931,327.

[0092] The sensor electronics 106 may also include one or more sensors, such as a sensor 212, which may be coupled to the processor 204. The sensor 212 may be a temperature sensor, an accelerometer, or another suitable sensor. The sensor electronics 106 may also include a power source, such as a capacitor or battery 214, which may be integrated into the sensor electronics 106, may be removable, or may be part of a separate electronics unit. The battery 214 (or other power storage component, e.g., a capacitor) may optionally be rechargeable via a wired or wireless (e.g., inductive or ultrasonic) recharging system 216. The recharging system 216 may harvest energy or may receive energy from an external or on-board source. In various embodiments, the recharging circuit may include a circuit that harvests energy from a triboelectric charging circuit, a piezoelectric charging circuit, an RF charging circuit, an optical charging circuit, an ultrasonic charging circuit, a thermal charging circuit, a thermal collection circuit, or a communication circuit. In some embodiments, the recharging circuit may recharge a rechargeable battery using power provided from a replaceable battery (e.g., a battery provided with the base component).

[0093] The sensor electronics 106 may also include one or more supercapacitors in the sensor electronics unit (as shown) or in the sensor mounting unit 290. For example, the supercapacitor may allow energy to be drawn from the battery 214 in a very consistent manner to extend the life of the battery 214. The battery 214 may recharge the supercapacitor after it has provided energy to the communications circuitry or processor 204, so that the supercapacitor is ready to provide energy during a subsequent period of high load. In some embodiments, the supercapacitor may be configured in parallel with the battery 214. The device may be configured to preferentially draw energy from the supercapacitor as opposed to the battery 214. In some embodiments, the supercapacitor may be configured to receive energy from a rechargeable battery for short-term storage and transfer energy to the rechargeable battery for long-term storage.

[0094] The supercapacitor can extend the operating life of the battery 214 by reducing strain on the battery 214 during periods of high load. In some embodiments, the supercapacitor reduces strain on the battery by at least 10% during high load. In some embodiments, the supercapacitor reduces strain on the battery by at least 20% during high load. In some embodiments, the supercapacitor reduces strain on the battery by at least 30% during high load. In some embodiments, the supercapacitor reduces strain on the battery by at least 50% during high load.

[0095] The sensor electronics 106 may also include wireless communication circuitry 218, which may include, for example, a wireless transceiver operably coupled to an antenna. The wireless communication circuitry 218 may be operably coupled to the processor 204 and may be configured to wirelessly communicate with one or more peripheral devices or other medical devices, such as an insulin pump or a smart insulin pen.

[0096] 2, medical device system 200 also includes optional external devices including, for example, peripheral device 250. Peripheral device 250 may be any suitable user computing device, such as, for example, a wearable device (e.g., an activity monitor) such as wearable device 120. In other examples, peripheral device 250 may be a handheld smart device (e.g., a smartphone or other device such as a proprietary handheld device available from Dexcom), tablet 114, smart pen 116, or dedicated computer 118 as shown in FIG.

[0097] Peripheral device 250 may include a UI 252, a memory circuit 254, a processor 256, a wireless communication circuit 258, a sensor 260, or any combination thereof. Peripheral device 250 does not necessarily include all of the components shown in Figure 2. Peripheral device 250 may also include a power source, such as a battery.

[0098] The UI 252 can be provided, for example, using any suitable input / output device of the peripheral device 250, such as a touch screen interface, a microphone (e.g., for receiving voice commands), or a speaker, a vibrating circuit, or any combination thereof. The UI 252 can receive information (e.g., instructions, glucose values) from a host or another user. The UI 252 can also deliver information to the host or other user, for example, by displaying UI elements on the UI 252. For example, the UI elements can show glucose or other analyte concentration values, glucose or other analyte trends, glucose or other analyte alerts, etc.

[0099] The processor 256 may be configured to present information to or receive input from a user via the UI 252. The processor 256 may also be configured to store and retrieve information, such as communication information (e.g., pairing information or data center access information), user information, sensor data, or trends, in the memory circuit 254. The wireless communication circuit 258 may include a transceiver and an antenna configured to communicate via a wireless protocol, such as any of the wireless protocols described herein. The sensors 260 may include, for example, an accelerometer, a temperature sensor, a location sensor, a biosensor, or a blood glucose sensor, a blood pressure sensor, a heart rate sensor, a respiration sensor, or another physiological sensor.

[0100] The peripheral devices 250 may be configured to receive and display sensor information that may be transmitted by the sensor electronics 106 (e.g., in a customized data package transmitted to a display device based on respective preferences). The sensor information (e.g., blood glucose concentration level) or alerts or notifications (e.g., “high glucose level”, “low glucose level”, or “decline rate alert”) may be communicated via the UI 252 (e.g., via a visual display, sound, or vibration). In some examples, the peripheral devices 250 may be configured to display or otherwise communicate the sensor information communicated from the sensor electronics 106 (e.g., in a data package transmitted to a respective display device). For example, the peripheral devices 250 may transmit processed data (e.g., an estimated analyte value level that may be determined by processing raw sensor data), such that a device receiving the data may not need to further process the data to determine usable information (such as an estimated analyte value level). In other examples, the peripheral devices 250 may process or interpret the received information (e.g., to issue an alert based on glucose values ​​or glucose trends). In various embodiments, the peripheral device 250 can receive information directly from the sensor electronics 106 or over a network (e.g., via a cellular or Wi-Fi network that receives information from the sensor electronics 106 or from a device that is communicatively coupled to the sensor electronics 106).

[0101] 2, medical device system 200 includes an optional medical device 270. For example, medical device 270 may be an external device used in addition to or instead of peripheral device 250. Medical device 270 may be or include any suitable type of medical or other computing device, including, for example, medical device 108, peripheral medical device 122, wearable device 120, wearable sensor 130, or wearable sensor 136 shown in FIG. 1. Medical device 270 may include a UI 272, a memory circuit 274, a processor 276, a wireless communication circuit 278, a sensor 280, a therapy circuit 282, or any combination thereof.

[0102] Like UI 252, UI 272 may be provided using any suitable input / output device of medical device 270, such as a touch screen interface, a microphone or speaker, a vibration circuit, or any combination thereof. UI 272 may receive information from a host or another user (e.g., glucose values, alert settings, calibration codings). UI 272 may also deliver information to a host or other user, such as by displaying UI elements on UI 252. For example, UI elements may show glucose or other analyte concentration values, glucose or other analyte trends, glucose or other analyte alerts, etc.

[0103] The processor 276 may be configured to present information to or receive input from a user via the UI 272. The processor 276 may also be configured to store and retrieve information, such as communication information (e.g., pairing information or data center access information), user information, sensor data, or trends, from the memory circuit 274. The wireless communication circuit 278 may include a transceiver and antenna configured to communicate via a wireless protocol, such as any of the wireless protocols described herein.

[0104] The sensor 280 may include, for example, an accelerometer, a temperature sensor, a position sensor, a biosensor, or a blood glucose sensor, a blood pressure sensor, a heart rate sensor, a respiration sensor, or another physiological sensor. The medical device 270 may include more than one sensor (or memory or other components), although only one sensor 280 is shown in the example of FIG. 2. In various examples, the medical device 270 may be a smart handheld glucose sensor (e.g., a blood glucose meter), a drug pump (e.g., an insulin pump), or other physiological sensor device, a therapy device, or a combination thereof.

[0105] In examples where the medical device 270 is or includes an insulin pump, the pump and the analyte sensor system 102 may communicate bidirectionally (e.g., the pump may request a change in the analyte transmission protocol, e.g., request data points or request data on a more frequent schedule), or the pump and the analyte sensor system 102 may communicate using one-way communication (e.g., the pump may receive analyte concentration level information from the analyte sensor system). In one-way communication, the glucose value may be embedded in an advertising message, which may be encrypted with a pre-shared key. In two-way communication, the pump may request a value and the analyte sensor system 102 may share or obtain and share that value in response to a request from the pump, and any or all of these communications may be encrypted using one or more pre-shared keys. The insulin pump may receive and track analyte (e.g., glucose) values ​​transmitted from the analyte sensor system 102 using one-way communication to the pump for one or more of a variety of reasons. For example, an insulin pump can interrupt or activate insulin delivery based on glucose values ​​falling below or above a threshold value.

[0106] In some examples, the medical device system 200 includes two or more peripheral devices and / or medical devices, each of which receives information directly or indirectly from the analyte sensor system 102. Because different display devices provide many different user interfaces, the content of the data package (e.g., amount, format, and / or type of data displayed, alarms, etc.) can be customized (e.g., programmed differently by the manufacturer and / or end user) for each device. For example, referring now to the example of FIG. 1, multiple different peripheral devices can wirelessly communicate directly with the sensor electronics 106 (e.g., on-skin sensor electronics 106 physically connected to the continuous analyte sensor 104, etc.) during a sensor session to enable multiple different types and / or levels of display and / or functionality related to the displayable sensor information or to conserve battery power of the sensor system 102, and one or more designated devices can communicate with the analyte sensor system 102 to relay (i.e., share) information to other devices, either directly or via a server system (e.g., a networked data center) 126.

[0107] 3 is a side view illustrating an exemplary analyte sensor 334 that may be implanted in a host. The housing 302 may be adhered to the skin of the host using an adhesive pad 308. The adhesive pad 308 may be formed from a stretchable material and may be removably attached to the skin using an adhesive. The sensor electronics may be positioned within the housing 302. The sensor 334 may extend from the housing 302 and under the skin of the host as shown.

[0108] 4 is a side view of another example analyte sensor 434 in an arrangement including a mounting unit 414 and an electronics unit 418. The mounting unit 414 can be adhered to the skin of a host using an adhesive pad 408, which can be similar to the adhesive pad 308 described herein. The electronics unit 418 comprises a housing 402 that can have sensor electronics positioned thereon. In some examples, the electronics unit 418 and mounting unit 414 are arranged in a manner similar to the sensor electronics 106 and sensor mounting unit 290 shown in FIGS. 1 and 2. For example, the sensor 434 can extend from the housing 402 via the mounting unit 414.

[0109] 5 is a close-up view of a distal portion of analyte sensor 534. Analyte sensor 534 illustrates one exemplary arrangement that may be used to implement an analyte sensor described herein, such as, for example, analyte sensor 104, 334, 434. Analyte sensor 534 may be adapted to be inserted under the skin of a host and may be mechanically coupled to a housing, such as housing 402, and / or to a mounting unit, such as mounting unit 414. Analyte sensor 534 may be electrically coupled to sensor electronics, which may be positioned within housing 302, 402.

[0110] The exemplary analyte sensor 534 shown in FIG. 5 includes an elongated conductor 541. The elongated conductor 541 may include a core having various layers positioned thereon. A first layer 538 at least partially surrounding the core includes a working electrode, for example, disposed within a window 539. In some embodiments, the core and first layer 538 are made of a single material (e.g., platinum, etc.). In some embodiments, the elongated conductor 541 is a composite of two conductive materials or a composite of at least one conductive material and at least one non-conductive material. A membrane system 532 is disposed over the working electrode and may cover other layers and / or electrodes of the sensor 534 as described herein.

[0111] The first layer 538 may be formed of an electrically conductive material. The working electrode (at window 539) is the exposed portion of a surface of the first layer 538. Thus, the first layer 538 is formed of a material configured to provide a suitable electroactive surface for the working electrode.

[0112] Examples of suitable materials include, but are not limited to, platinum, platinum-iridium, gold, palladium, iridium, graphite, carbon, conductive polymers, alloys, and the like.

[0113] The second layer 540 surrounds at least a portion of the first layer 538, thereby defining a boundary of the working electrode. In some embodiments, the second layer 540 acts as an insulator and is formed of an insulating material, such as polyimide, polyurethane, parylene, or any other suitable insulating material or materials. In some embodiments, the second layer 540 is configured such that the working electrode (of layer 538) is exposed through a window 539.

[0114] In some embodiments, the sensor 534 further includes a third layer 543 including a conductive material. The third layer 543 may include a reference electrode. In some embodiments, the third layer 543 including the reference electrode is formed from a silver-containing material that is applied onto the second layer 540 (e.g., an insulator). The silver-containing material may include a variety of materials and may be in a variety of forms, such as, for example, Ag / AgCl-polymer pasts, paints, polymer-based conductive mixtures, inks, etc.

[0115] The analyte sensor 534 may include two (or more) electrodes, e.g., a working electrode exposed at layer 538 and at window 539, and at least one additional electrode, such as a reference electrode at layer 543. In the exemplary arrangements of Figures 5 and 6, the reference electrode also functions as a counter electrode, while other arrangements may include a separate counter electrode. The analyte sensor 534 may be used with a mounting unit in some embodiments, while in other embodiments the analyte sensor 534 may be used with other types of sensor systems. For example, the analyte sensor 534 may be part of a system that includes a battery and a sensor in a single package, and may optionally include, for example, near field communication (NFC) circuitry.

[0116] 6 is a cross-sectional view through the sensor 534 of FIG. 5 on plane 2-2 illustrating the membrane system 532. The membrane system 532 can include multiple domains (e.g., layers). In an embodiment, the membrane system 532 can include an enzyme domain 542, a diffusion resistance domain 544, and a bio-protection domain 546 disposed about a working electrode. In some embodiments, a combined diffusion resistance domain and bio-protection domain can be included in the membrane system 532 (e.g., the functionality of both the diffusion resistance domain and the bio-protection domain are incorporated into one domain).

[0117] The membrane system 532 also includes, in some embodiments, an electrode layer 547. The electrode layer 547 can be disposed between the surfaces of the working and reference electrodes to provide an environment that facilitates an electrochemical reaction between the electrodes. For example, the electrode layer 547 can include a coating that maintains a layer of water on the electrochemically reactive surfaces of the sensor 534.

[0118] In some embodiments, the sensor 534 may be configured for short-term implantation (e.g., about 1 day to about 30 days). However, it is understood that the membrane system 532 may be modified for use in other devices, e.g., by simply including one or more domains or by including additional domains. For example, the membrane system 532 may include multiple resistive layers, or multiple enzyme layers. In some embodiments, the resistive domain 544 may include multiple resistive layers, or the enzyme domain 542 may include multiple enzyme layers.

[0119] The diffusion resistance domain 544 can include a semi-permeable membrane that controls the flux of oxygen and glucose to the underlying enzyme domain 542. As a result, the upper linearity limit of the glucose measurement is extended to a value much higher than that achieved without the diffusion resistance domain 544.

[0120] In some examples, the membrane system 532 can include a bioprotective domain 546, also referred to as a domain or biointerface domain, that includes a base polymer, but some examples of the membrane system 532 can also include multiple domains or layers, including, for example, an electrode domain, an interference domain, or a cell disruption domain, as described in more detail elsewhere herein, as well as in U.S. Patent Nos. 7,494,465, 8,682,608, and 9,044,199, the entire contents of which are incorporated herein by reference.

[0121] For example, it should be understood that sensor membranes improved for other sensors may include fewer or additional layers. For example, in some embodiments, the membrane system 532 may include one electrode layer, one enzyme layer, and two bio-protection layers, while in other embodiments, the membrane system 532 may include one electrode layer, two enzyme layers, and one bio-protection layer. In some embodiments, the bio-protection layer may be configured to function as a diffusion resistance domain 544 and control the flux of an analyte (e.g., glucose) to the underlying membrane layer.

[0122] In some embodiments, one or more domains of the sensing membrane may be formed from materials such as silicone, polytetrafluoroethylene, ethylene tetrafluoroethylene copolymers, polyolefins, polyesters, polycarbonates, biostable polytetrafluoroethylene, homopolymers, copolymers, terpolymers of polyurethane, polypropylene (PP), polyvinylchloride (PVC), polyvinylidene fluoride (PVDF), polybutylene terephthalate (PBT), polymethylmethacrylate (PMMA), polyether ether ketone (PEEK), polyurethanes, cellulosic polymers, poly(ethylene oxide), poly(propylene oxide) and copolymers and blends thereof, polysulfones and block copolymers thereof (e.g., diblock, triblock, alternating, random, and graft copolymers, etc.).

[0123] In some examples, the sensor membrane can be deposited on the electroactive surface of the electrode material using known thin or thick film techniques (e.g., spraying, electrodeposition, dipping, etc.) The sensor membrane disposed on the working electrode need not be of the same structure as the sensor membrane disposed on the reference electrode, e.g., the enzyme domain 542 deposited on the working electrode need not necessarily be deposited on the reference or counter electrodes.

[0124] Although the embodiments illustrated in Figures 5 and 6 involve a circumferentially extending membrane system, the membranes described herein may be applied to any planar or non-planar surface, such as the substrate-based sensor structures of U.S. Pat. No. 6,565,509 to Say et al., which is incorporated by reference.

[0125] In an embodiment in which the analyte sensor 534 is a glucose sensor, the glucose analyte may be detected using glucose oxidase. Glucose oxidase reacts with glucose to produce hydrogen peroxide (H2O2). The hydrogen peroxide reacts with the surface of the working electrode to release two protons (2H + ), 2 electrons (2e - ) and one oxygen molecule (O2). This produces an electronic current that can be detected by the sensor electronics 106. The amount of current is a function of the glucose concentration level. A calibration curve can be used to provide an estimated glucose concentration level based on the measured current. The amount of current is also a function of the diffusivity of glucose through the sensor membrane. Glucose diffusivity can change over time, which can cause the sensor glucose sensitivity to change or "drift" over time.

[0126] Figure 7 is a schematic illustration of a circuit 700 representing the behavior of an exemplary analyte sensor, such as the analyte sensor 534 shown in Figures 5 and 6. As described above, the interaction between hydrogen peroxide (produced from the interaction of glucose analyte with glucose oxidase) and a working electrode (WE) 704 creates a voltage difference between the working electrode (WE) 704 and a reference electrode (RE) 706, which drives a current. The current is measured by sensor electronics, such as the sensor electronics 106 of Figures 1 and 2, and may constitute all or a portion of the raw sensor signal used to estimate the analyte concentration (e.g., glucose concentration).

[0127] The circuit 700 also includes a double layer capacitance (Cdl) 708 that occurs at the interface between the working electrode (WE) 704 and the adjacent membrane (not shown in FIG. 7, but see, e.g., FIGS. 5 and 6 above). The double layer capacitance (Cdl) may occur at the interface between the working electrode 704 and the adjacent membrane due to the presence of two layers of ions with opposite polarity, as may occur during application of a voltage applied between the working electrode 704 and a reference electrode. The equivalent circuit 700 may also include a polarization resistance (Rpol) 710, which may be relatively large and may be modeled, for example, as a static value (e.g., 100 megaohms) or as a variable quantity that changes as a function of glucose concentration level.

[0128] An estimated analyte concentration may be determined from the raw sensor signal based on the measured current (or charge flow) through the analyte sensor membrane 712 when a bias potential is applied to the sensor circuit 700. For example, the sensor electronics or another suitable computing device can use the raw sensor signal and the sensitivity of the sensor to correlate the detected current flow to a glucose concentration level to generate an estimated analyte value. In some examples, the device also uses break-in characteristics as described herein.

[0129] Referring to the equivalent circuit 700, when a voltage is applied across the working electrode 704 and the reference electrode 706, current can be considered to flow (forward or backward depending on the polarity) through the transmitter internal electronics (represented as R Tx internal) 711, through the reference electrode (RE) 706 and the working electrode (WE) 704, which can be designed to have a relatively low resistance, and through the sensor membrane 712 (Rmembr, relatively small). Also, depending on the state of the circuit, current can flow through a relatively large polarization resistance 710 (shown as a fixed resistance, but which can be a variable resistance that changes with the glucose level in the body, with higher glucose levels resulting in a smaller polarization resistance), through the double layer capacitance 708 (i.e., to charge the double layer membrane capacitor formed at the working electrode 704), or both.

[0130] The impedance (or conductance) of the membrane (Rmembr) 712 is related to the mobility of electrolytes in the membrane, which in turn is related to the diffusivity of glucose in the membrane. Lower impedance (i.e., higher conductance as the mobility of electrolytes in the membrane 712 increases) increases glucose sensitivity (i.e., higher glucose sensitivity means that a particular glucose concentration produces a larger signal in the form of more current or charge flow). Impedance, glucose diffusivity, and glucose sensitivity are further described in U.S. Patent Application Publication No. 2012 / 0262298, the entire contents of which are incorporated by reference.

[0131] In various embodiments, the analyte sensor is packaged with a sensor applicator. Figures 8, 9A-9D, 10, and 11 show exemplary implementations of a sensor applicator. Figure 8 shows an exploded side view of one embodiment of a sensor applicator 912. In this embodiment, the sensor applicator 912 includes an applicator body 918 that helps adjust and guide the sensor applicator components. The applicator body 918 includes an applicator body base 960 that matingly engages the mounting unit 914 (Figure 11) and an applicator body cap 962 that allows for proper relationship (e.g., stop) between the sensor applicator components.

[0132] The guide tube subassembly 920 includes a guide tube carrier 964 and a guide tube 966. In some embodiments, the guide tube is a cannula. The guide tube carrier 964 slides along the applicator body 918 to maintain the proper relative position of the guide tube 966 during insertion and subsequent retraction. For example, before and during insertion of a sensor, the guide tube 966 extends through the contact subassembly 926 to maintain an opening that allows easy insertion of a needle therethrough (see FIGS. 9A-9D). During retraction of the sensor, the guide tube subassembly 920 is pulled back to engage the needle and associated moving components, retracting the needle and associated moving components into the sensor applicator 912 (see FIGS. 9C and 9D). In some embodiments, a lubricant (e.g., Vaseline) is disposed within the contact subassembly 926 to surround the guide tube 966 (e.g., cannula), thereby allowing the guide tube 966 to easily retract back into the sensor applicator 912, for example, without causing compression or deformation of the contact subassembly 926.

[0133] A needle subassembly 968 is provided that includes a needle carrier 970 and a needle 972. The needle carrier 970 cooperates with other sensor applicator components to carry the needle 972 between its extended and retracted positions. The needle 972 can be of any suitable size capable of containing the analyte sensor 932 (FIGS. 9A-9D) and aiding in its insertion into the host. Exemplary sizes include about 32 gauge or less to about 18 gauge or more, more preferably about 28 gauge to about 25 gauge, to provide comfortable insertion for the host. With reference to the inner diameter of the needle, about 0.006 inches to about 0.023 inches may be used, and 0.013 inches may also be used. The needle carrier 970 is configured to engage with the guide tube carrier 964, while the needle 972 is configured to slidably nest within the guide tube 966, which allows for easy guided insertion (and retraction) of the needle through the contact subassembly 926.

[0134] A push rod subassembly 974 is provided that includes a push rod carrier 976 and a push rod 978. The push rod carrier 976 cooperates with other sensor applicator components to ensure that the analyte sensor 932 is properly inserted into the host's skin, i.e., the push rod carrier 976 carries the push rod 978 between its extended and retracted positions. In this embodiment, the push rod 978 is configured to slidably nest within the cannula 901 of the needle 972, allowing the analyte sensor 932 to be pushed (released) from the needle 972 upon retraction of the needle 972. This is described in more detail with reference to Figures 9A-9D. In some examples, a slight bend or serpentine shape is designed or allowed into the sensor to maintain the sensor within the needle 972 by interference. Without being bound by theory, it is believed that a slight friction fit of the analyte sensor 932 within the needle 972 may minimize movement of the analyte sensor 932 during withdrawal of the needle 972 and maintain the analyte sensor 932 within the needle prior to withdrawal of the needle 972.

[0135] A plunger subassembly 922 is provided that includes a plunger 980 and a plunger cap 982. The plunger subassembly 922 cooperates with other sensor applicator components to ensure proper insertion and subsequent retraction of the needle 972. In this embodiment, the plunger 980 is configured to engage a push rod 978 to ensure that the analyte sensor 932 remains extended (i.e., within the host) during retraction, as will be described in more detail with reference to FIG.

[0136] 9A-9D are schematic side cross-sectional views illustrating applicator components and their cooperating relationships at various stages of sensor insertion. FIG. 9A shows an embodiment of a needle 972 and analyte sensor 932 loaded prior to sensor insertion. FIG. 9B shows an embodiment of a needle 972 and analyte sensor 932 after sensor insertion. FIG. 9C shows an embodiment of an analyte sensor 932 and needle 972 during needle retraction. FIG. 9D shows an embodiment of an analyte sensor 932 remaining in the contact subassembly 926 after needle retraction. While the embodiments of FIGS. 8, 9A-9D, and 11 suggest manual insertion and / or retraction of the various components, automation of one or more of the stages may also be employed. For example, a spring-loaded mechanism may be implemented that may be triggered to automatically insert and / or retract the sensor, needle, or other cooperating applicator components.

[0137] 9A, the analyte sensor 932 is shown disposed within a needle 972 that is disposed within a guide tube 966. In this embodiment, the guide tube 966 is provided to maintain an opening in the contact subassembly 926 and / or contact portion 928 to minimize friction between the needle 972 and the contact subassembly 926 and / or contact portion 928 during insertion and retraction of the needle 972. However, the guide tube 966 is an optional component that can be advantageous in some embodiments where the contact subassembly 926 and / or contact portion 928 are formed from an elastomer or other material having a relatively high coefficient of friction. For example, the guide tube 966 may be omitted in other embodiments where the contact subassembly 926 and / or contact portion 928 are formed from a material having a relatively low coefficient of friction (e.g., a hard plastic or metal). A guide tube 966 or the like may be advantageous in examples where the contact subassembly 926 and / or contacts 928 are formed from a material designed to frictionally retain the analyte sensor 932 (see FIG. 9D ), e.g., by relaxation properties such as an elastomer. In these examples, the guide tube 966 may be provided to facilitate insertion of the needle 972 through the contacts 928 while allowing frictional retention of the contacts 928 on the analyte sensor 932 upon subsequent needle retraction. Stabilization of the analyte sensor 932 at or on the contacts 928 is described in more detail with reference to FIG. 9D . Although FIG. 9A illustrates the needle 972 and analyte sensor 932 inserted into the contact subassembly 926 as an initial loaded configuration, alternative embodiments contemplate loading the needle 972 through the guide tube 966 and / or contacts 928 prior to sensor insertion.

[0138] 9B, the analyte sensor 932 and needle 972 are shown in an extended position. At this stage, the push rod 978 has been pushed into a forward position, such as by pushing the plunger shown in FIG. 7. The plunger 980 (FIG. 9) is designed to cooperate with other of the sensor applicator components to ensure that the analyte sensor 932 and needle 972 extend together in the forward position (as shown). For example, the push rod 978 can be designed to cooperate with other of the sensor applicator components to ensure that the analyte sensor 932 maintains a forward position simultaneously within the needle 972.

[0139] Referring to FIG. 9C, the needle 972 is shown during the retraction process. At this stage, the push rod 978 is held in its extended (forward) position to maintain the analyte sensor 932 in its extended (forward) position until the needle 972 is substantially fully retracted from the contact 928. At the same time, the cooperating sensor applicator component retracts the needle 972 and guide tube 966 rearwardly by a pulling action (manual or automatic) thereon. In a preferred embodiment, the guide tube carrier 964 (FIG. 9) engages with the cooperating applicator component such that a rearward (retraction) motion applied to the guide tube carrier retracts the needle 972 and guide tube 966 without (first) retracting the push rod 978. In an alternative embodiment, the push rod 978 may be omitted and the analyte sensor 932 is held in its forward position by a cam, elastomer, or the like that contacts one portion of the sensor while the needle moves over another portion of the sensor. One or more slots can be cut into the needle to maintain contact with the sensor during retraction of the needle.

[0140] 9D , the needle 972, guide tube 966, and push rod 978 are all retracted from the contact subassembly 926, leaving the analyte sensor 932 disposed therein. The cooperating sensor applicator components are designed such that the push rod 978 retracts along with the needle 972 and guide tube 966 when the needle 972 is substantially clear of the contacts 928 and / or contact subassembly 926. The sensor applicator 912 can then be released (manually or automatically) from the contacts 928.

[0141] In various examples, the contacts 928 are elastomeric contacts to ensure a retention force that holds the analyte sensor 932 within the mounting unit and to ensure a stable electrical connection between the analyte sensor 932 and its associated contacts 928. Although the illustrated embodiments and associated text describe the analyte sensor 932 extending through and forming a friction fit therein, various alternatives are contemplated. In some examples, the sensor 932 is configured to be disposed adjacent to the contacts 928 (rather than between the contacts 928). The contacts 928 may be constructed with various known configurations, e.g., metal contacts, cantilever fingers, pogo pins, etc., that are configured to press against the sensor after needle retraction.

[0142] The illustrated embodiment is designed with a coaxial contact 928, i.e., the contact 928 is configured to contact the working and reference electrodes of the analyte sensor 932 axially along the distal portion of the analyte sensor 932. For example, the working electrode of the analyte sensor 932 may extend farther than the reference electrode, which allows for a coaxial connection between the electrodes and the contact 928 at spaced locations along the distal portion of the sensor.

[0143] Figure 10 is a perspective view of a sensor applicator 912 and a mounting unit 914 according to one embodiment including a safety latch mechanism 984. Although Figure 10 shows the sensor applicator 912 engaged with the sensor mounting unit 914, it will be understood that the sensor applicator 912 may instead be configured to engage with a housing, such as the housing 302 described with respect to Figure 3.

[0144] 10, the safety latch mechanism 984 is configured to lock the plunger subassembly 922 in a resting position such that the plunger subassembly 922 cannot be accidentally depressed prior to the release of the safety latch mechanism 984. In this example, the analyte sensor 932 is preferably packaged (e.g., shipped) in this locked configuration, with the safety latch mechanism 984 holding the plunger subassembly 922 in its extended position. This may prevent the analyte sensor 932 from being prematurely inserted (e.g., accidentally released). The safety latch mechanism 984 may be configured such that a pulling force shown in the direction of the arrow (see FIG. 10) will unlock the safety latch mechanism 984 on the plunger subassembly 922, thereby allowing sensor insertion. Although one safety latch mechanism 984 for locking the plunger subassembly 922 is illustrated and described herein, a variety of safety latch mechanism configurations that lock the sensor to prevent it from being released prematurely (i.e., lock the sensor prior to release of the safety latch mechanism) are understood by those skilled in the art and are contemplated as being within the scope of the preferred embodiments.

[0145] 10 additionally illustrates a force locking mechanism 986 included in a particular alternative embodiment of the sensor system, the force locking mechanism 986 configured to ensure a proper fit between the electronics unit (e.g., electronics unit 418 of FIG. 4) and the mounting unit 914. In some situations, it can be advantageous to ensure that the electronics unit is properly mated (e.g., a snap-fit ​​or a sealing fit) to the mounting unit. Thus, upon release of the sensor applicator 912 from the mounting unit 914 after sensor insertion, the force locking mechanism 986 allows a user to ensure a proper fit and / or seal therebetween.

[0146] In practice, the user pivots (e.g., lifts or twists) the force lock mechanism such that it provides a force to the electronics unit (such as electronics unit 418 in FIG. 4) by pulling up on the circular tab illustrated in FIG. 10. The force lock mechanism is preferably then released. Although one system and one method for providing a secure and / or sealed fit between the electronics unit and the mounting unit have been illustrated, a variety of other force lock mechanisms utilizing various systems and methods for providing a secure and / or sealed fit between the electronics unit and the mounting unit (housing) may be employed.

[0147] In some examples, the sensor applicator 912 shown in FIGS. 8, 9A-9D, and 10 can also include a transmitter 985. The transmitter 985 is configured to generate a wireless signal that can be detected by the sensor electronics 106, as described herein. The wireless signal generated by the transmitter 985 can be in a first state, i.e., a non-deployed state, before the sensor applicator 912 inserts a sensor. After and / or once the sensor is inserted, the transmitter 985 can change the wireless signal to a second state, i.e., a deployed state. The sensor electronics can detect the change in state of the wireless signal to determine whether to transition from a sleep mode to an active mode, as described herein.

[0148] The transmitter 985 may be of any suitable design that generates a wireless signal having at least two states. In some embodiments, the transmitter 985 is an electromagnet or a permanent magnet, and the wireless signal is a magnetic field generated by the transmitter 985. One state of the wireless signal may be the presence of a magnetic field (e.g., a magnetic field having a field strength greater than a threshold). Another state of the wireless signal may be the absence of a magnetic field (e.g., a magnetic field having a field strength less than a threshold). The presence of a magnetic field may indicate a non-deployed state and the absence of a magnetic field may indicate a deployed state, or vice versa.

[0149] In some embodiments in which the transmitter 985 includes an electromagnet and / or a permanent magnet, a first state of the wireless signal may correspond to a first magnetic polarity of the magnetic field and a second state of the wireless signal may correspond to a second magnetic polarity of the magnetic field that may be opposite to the first polarity. One polarity of the magnetic field may correspond to a non-deployed state and another polarity of the magnetic field may correspond to a deployed state. The transmitter 985 may transition the wireless signal from the first state to the second state, such as by reversing the direction of a current provided to the electromagnet and / or by reversing the physical orientation of the magnet.

[0150] Other suitable transmitter arrangements may also be used to modify the state of the wireless signal in other ways. In some embodiments, the transmitter 985 is or includes an optical transmitter configured to generate an optical signal. In some embodiments, the transmitter 985 is or includes an acoustic transmitter configured to generate an acoustic signal. In some embodiments, the transmitter 985 is or includes a radio frequency transmitter, such as an RFID transmitter.

[0151] FIG. 11 illustrates another embodiment of an analyte sensor applicator 1100. In the embodiment of FIG. 11, the sensor applicator 1100 includes an applicator housing 1104. The sensor applicator 1100 is automated, e.g., includes a spring-loaded mechanism (not shown in FIG. 11) to initiate sensor insertion. For example, the spring-loaded mechanism can be activated by depressing an insertion button 1106. A safety latch mechanism 1105 is positioned over the insertion button 1106 to prevent accidental insertion of the analyte sensor 1132. The safety latch mechanism 1105 can be removed, e.g., by pulling it away from the applicator housing 1104.

[0152] 11 includes a window 1108 showing the components inside the applicator housing 1104 including, for example, needle 1172 and mounting unit 1114. The mounting unit 1114 is coupled to an exemplary adhesive pad 1110 for adhering the mounting unit 1114 to the skin of a host. In embodiments that do not include a separate electronics unit, such as the embodiment of FIG. 3, the housing 302 and associated adhesive pad 308 may be positioned in a similar manner as the mounting unit 1114 and adhesive pad 1110.

[0153] In the example of Figure 11, the push rod 1178 can operate in a manner similar to the push rod 978 described above to push the analyte sensor 1132 into the host. The lumen 1101 of the needle 1172 can include a hydrating agent, for example, as described herein. In the example of Figure 11, the applicator 1100 also includes a transmitter 1112, which can be disposed, for example, similar to the transmitter 985 of Figure 10.

[0154] 12 illustrates an example of an analyte sensor system 1200 including an analyte sensor 1206 and sensor electronics 1202. The analyte sensor 1206 may be arranged, for example, as described herein with respect to Figures 3-6 and / or according to any other suitable arrangement, such as, for example, a planar sensor arrangement.

[0155] The sensor electronics 1202 is positioned within the housing 1204. The analyte sensor 1206 extends from the housing 1204 as shown. In some examples, the analyte sensor 1206 is mechanically coupled to the housing 1204, for example, as illustrated in FIG 3. In some examples, the analyte sensor 1206 is mechanically coupled to a sensor mounting unit, as described herein.

[0156] The analyte sensor 1206 may be in electrical communication with an analog front end 1212 of the sensor electronics 1202. In examples where the analyte sensor 1206 is mechanically coupled to the housing 1204, the analyte sensor 1206 may extend through the housing 1204 in a sealed manner and be in direct electrical contact with the analog front end 1212. In examples where the analyte sensor 1206 is mechanically coupled to a sensor mounting unit, the electrical connection between the analyte sensor 1206 and the analog front end 1212 may be through a connector between the sensor mounting unit and the housing 1204.

[0157] The analog front end 1212 may be configured to receive analog electrical signals from various components of the sensor electronics 1202 and provide corresponding digital electrical signals to the control circuitry 1220. For example, as described, the analyte sensor 1206 may be in electrical communication with the analog front end 1212 to provide an analog raw sensor signal to the analog front end 1212. The analog front end 1212 may include various amplifiers, filters, conditioners, analog-to-digital converters, and / or the like to condition the raw sensor signal and convert it to a digital raw sensor signal that can be provided to the control circuitry 1220. The control circuitry 1220 may be configured to convert the digital raw sensor signal to an estimated analyte value that can be output as described herein.

[0158] The analog front end 1212 may also be in communication with the deployment sensor 1210. The deployment sensor 1210 receives a wireless signal 1214. The wireless signal 1214 may be generated by a transmitter at the applicator, such as, for example, the transmitter 1112 of the applicator 1100 and / or the transmitter 985 of the applicator 912. The deployment sensor 1210 may be configured to detect the wireless signal 1214 and generate an output indicative of a state of the wireless signal 1214. In embodiments in which the wireless signal 1214 is a magnetic signal, the deployment sensor 1210 may be or comprise a magnetic sensor, such as a Tunnel Magnetoresistance effect (TMR) sensor. In embodiments in which the wireless signal 1214 is an optical signal, the deployment sensor 1210 may be or comprise a photoresistor or another optical sensor. In embodiments where the wireless signal 1214 is a radio frequency (RF) or other similar signal, the deployment sensor 1210 may include an antenna and / or other RF receiver components. The analog front end 1212 may receive the output of the deployment sensor 1210 and provide the output to the control circuitry 1220 for further processing. In some embodiments, as shown in FIG. 12 , the analog front end 1212 and the control circuitry 1220 may be coupled to the analyte sensor 1206 prior to deployment. In this manner, the analog front end 1212 and the control circuitry 1220 may detect the deployment of the analyte sensor 1206 (e.g., via the wireless signal 1214) close in time to the actual insertion of the analyte sensor 1206.

[0159] 12, the analog front end 1212 includes circuitry for receiving and transmitting near field communication (NFC) signals 1216. The NFC signals 1216 may be used to communicate with various external devices. In some embodiments, the wireless signals 1214 may be implemented as NFC signals 1216.

[0160] The control circuitry 1220 is configured to receive digital signals from the analog front end 1212 and perform various processing on the signals. For example, the control circuitry 1220 may be and / or include a microcontroller or other processor. One or more processors of the control circuitry 1220 may be programmed to execute software instructions to perform various operations, for example, as described herein. The software instructions may be stored in a data storage device that may be part of the control circuitry 1220 or may be implemented in a different location.

[0161] In some examples, the control circuit 1220 converts the raw sensor signal (e.g., a digital raw sensor signal) into a corresponding estimated analyte value. The control circuit 1220 may provide as an output result data including the estimated analyte value, for example, in a manner described herein. In the example of FIG. 12, the control circuit 1220 communicates with a temperature sensor 1222, for example, as described herein. In this example, the temperature sensor 1222 is a digital sensor. In other examples, an analog temperature sensor (or other sensor as described herein) may communicate with the control circuit 1220 via the analog front end 1212. In some examples, the control circuit 1220 is also configured to communicate with one or more external devices via a short-range wireless communication medium 1218, for example, Bluetooth, Bluetooth LE, etc.

[0162] The control circuitry 1220 may also be programmed to transition the analyte sensor system 1200 from a sleep mode to an active mode. For example, various components of the sensor electronics 1202 are powered by the battery 1208. In some examples, the battery 1208 is incorporated when the analyte sensor system 1200 is manufactured. In some examples, the analyte sensor system 1200 is configured to operate for its entire life cycle on a single charge of the battery 1208. Thus, the analyte sensor system 1200 may be configured in a sleep mode after manufacture. In the sleep mode, the sensor electronics 1202 maintains the analyte sensor system 1200 in a configuration for low power consumption. For example, non-essential components of the analyte sensor system 1200 may be switched off. Also, for example, operations performed by the sensor electronics 1202 may be minimized to conserve power. The control circuitry 1220 may be programmed to maintain the sleep mode until the analyte sensor 1206 is inserted into a host in vivo and a sensor session is initiated.

[0163] When the control circuitry 1220 determines that a sensor session should begin, the control circuitry 1220 transitions the analyte sensor system 1200 into an active mode. This may include, for example, applying bias conditions to the analyte sensor, determining and outputting an estimated analyte concentration using a raw sensor signal (e.g., a digital raw sensor signal), etc. The sensor electronics 1202 may determine to transition the analyte sensor system 1200 into an active mode, for example, using the wireless signal 1214 and / or the raw sensor signal provided by the analyte sensor 1206. Although certain circuits, components, and interconnections are illustrated in the exemplary analyte sensor system 1200 shown in FIG. 12, alternative embodiments may incorporate additional, fewer, and / or alternative circuits, components, and / or interconnections.

[0164] 13 is a flow chart illustrating an embodiment of a process flow 1300 that may be performed by the sensor electronics of the sensor system to transition the sensor system from a sleep mode to an active mode. In operation 1302, the sensor electronics 1202 evaluates a test condition. The test condition is a condition indicative of a potential deployment or insertion of the analyte sensor 1206. Evaluating the test condition may include polling the deployed sensor 1210 and / or the analyte sensor 1206. For example, the test condition may be based on a raw sensor signal generated by the analyte sensor 1206 and / or a signal received from the deployed sensor 1210.

[0165] In some examples, the test condition is based at least in part on a raw sensor signal generated by the analyte sensor 1206. For example, the raw sensor signal may change after the analyte sensor 1206 is inserted into a host, e.g., under the skin as described herein. For example, prior to insertion, the analyte sensor 1206 may generate a small signal or no signal because the analyte sensor system 1200 may be packaged for storage and / or shipping such that negligible electrochemical activity occurs at the analyte sensor 1206. However, once inserted, the analyte sensor 1206 may begin to generate a non-negligible raw sensor signal as in vivo reactions begin to occur. Thus, the sensor electronics 1202 may perform operation 1302 by polling the raw sensor signal and comparing it to a deployment test threshold. If the raw sensor signal is near the deployment test threshold, the test condition may be met. In another example, the raw sensor signal may be expected to exhibit a particular or predetermined profile or characteristic over a particular or predetermined time period, and the test condition may be satisfied when the raw sensor signal is determined to match the expected profile or characteristic.

[0166] In some examples, the sensor electronics 1202 evaluates the test condition at least in part by examining an output of the deployment sensor 1210, for example, to determine if the wireless signal 1214 received by the deployment sensor 1210 has changed to a deployed state. In some examples, testing for the deployment state includes a combination of examining the raw sensor signal and examining the output of the deployment sensor 1210. For example, the sensor electronics 1202 may find that the test condition is met if the raw sensor signal is greater than a deployment test threshold and the wireless signal 1214 has changed state. In another example, the sensor electronics 1202 may find that the test condition is met if the raw sensor signal is greater than a deployment test threshold or the wireless signal 1214 has changed state. If the test condition is not met in operation 1302, the sensor electronics 1202 may keep the analyte sensor system 1200 in a sleep mode and return to operation 1302. For example, the sensor electronics 1202 may be configured to perform operation 1302 periodically (eg, every 5 minutes, every 30 seconds).

[0167] If the test condition is met in operation 1302, the sensor electronics 1202 determines whether the analyte sensor system 1200 is ready for a sensor session in operation 1304. This may include checking one or more factors that trend indicative of whether the analyte sensor 1206 is inserted and ready for use. For example, the sensor electronics 1202 may perform an insertion test to determine whether a raw sensor signal provided by the analyte sensor 1206 is consistent with the analyte sensor 1206 being positioned in vivo after insertion. For example, if the raw sensor signal remains above a deployment test threshold for a threshold time period, it may indicate that an insertion of the analyte sensor 1206 has occurred. On the other hand, if the raw sensor signal falls below the deployment test threshold, it may indicate that a test condition was not prompted by the sensor insertion. One exemplary insertion test is described herein with respect to FIG. 14.

[0168] Also, in some examples, the sensor electronics 1202 performs a deployment test in addition to or instead of the insertion test. The deployment test may be based on the wireless signal 1214. For example, as described herein, when an applicator is used to insert the analyte sensor 1206 and / or is removed from the remainder of the analyte sensor system 1200, it may trend the state of the wireless signal 1214 from a non-deployed state to a deployed state. The deployment test may include determining whether the wireless signal 1214 remains in one state for a stability threshold time period. If the wireless signal 1214 remains in one state for a stability threshold time period, the sensor electronics 1202 may take a response action. For example, if the state of the wireless signal 1214 remains in a deployed state for a stability threshold time period, it may indicate that insertion of the analyte sensor 1206 has occurred and that the analyte sensor system 1200 is ready to transition to an active mode and initiate a sensor session. The response action may include transitioning to an active mode by initiating a sensor session, as described herein. On the other hand, if the wireless signal 1214 returns to the initial non-deployed state for the stability threshold time period, it may indicate that the test condition was not prompted by the sensor insertion. The response action may include returning to a sleep mode. In some examples, if the wireless signal 1214 oscillates and does not settle to any state for the stability threshold time period, it may indicate that the test condition was not prompted by the sensor insertion. The response action may include returning the analyte sensor system 1200 to a sleep mode. An exemplary arrangement for performing a deployment test is provided herein with respect to FIG. 15.

[0169] The sensor electronics 1202 may determine whether the analyte sensor system 1200 is ready for the active mode based on an insertion test, a deployment test, or both. An exemplary arrangement for determining whether the analyte sensor system 1200 is ready for the active mode using an insertion test and a deployment test is provided herein with respect to FIG. 16. An exemplary arrangement for determining whether the analyte sensor system 1200 is ready for the active mode using a deployment test without an insertion test is provided herein with respect to FIG. 17.

[0170] If deployment is not verified at operation 1304, the sensor electronics 1202 may return and / or maintain the analyte sensor system 1200 in a sleep mode at operation 1306 and then return to periodic testing for test conditions at operation 1302. If deployment is verified at operation 1304, the sensor electronics may transition the analyte sensor system 1200 to an active mode at operation 1308, for example, by initiating a sensor session. Initiating a sensor session may include, for example, applying bias conditions to the analyte sensor 1206, initiating a warm-up or break-in period of the analyte sensor system 1200, and / or beginning to determine an estimated glucose value from a received raw sensor signal.

[0171] 14 is a state diagram illustrating one example of a workflow 1400 that may be executed by the sensor electronics 1202 of the analyte sensor system 1200 of FIG. 12 to perform an insertion test. This may include determining whether a raw sensor signal generated by the analyte sensor 1206 indicates that the analyte sensor 1206 has been inserted under the skin of a host. As described herein, electrochemical activity in the analyte sensor 1206 may begin and / or increase when the analyte sensor 1206 is inserted in vivo under the skin of a host. Thus, the raw sensor signal may also increase after the analyte sensor 1206 is inserted in vivo under the skin of a host. In some examples, performing the insertion test includes detecting such an increase in the raw sensor signal.

[0172] Workflow 1400 may be executed when a test condition occurs, for example, as described with respect to operation 1302. In some examples, workflow 1400 illustrates one example way that sensor electronics 1202 may execute all or a portion of operation 1304 of process flow 1300 of FIG.

[0173] At the start state 1402, the sensor electronics 1202 tests the raw sensor signal generated by the analyte sensor 1206 to determine whether it indicates that the analyte sensor 1206 has been inserted in vivo. This may be performed, for example, by comparing the raw sensor signal to an insertion condition. The insertion condition may be, for example, a threshold signal level, whether the raw sensor signal maintains a threshold signal value for a threshold time, whether the raw sensor signal exhibits stability of a threshold value, etc. In some examples, the comparison of the raw sensor signal to the insertion condition may be performed after an insertion threshold time period has elapsed since the workflow 1400 was initiated. This may allow, for example, for the raw sensor signal from the analyte sensor 1206 to further increase as a result of being in the body for a period of time. Insertion may be verified if the raw sensor signal is above a threshold after the insertion threshold time period.

[0174] If the insertion is not verified (e.g., the raw sensor signal does not meet the insertion condition), the sensor electronics 1202 may proceed to a fail state 1404 and return an indication that the insertion is not verified. If the insertion is verified (e.g., the raw sensor signal meets the insertion condition), the sensor electronics 1202 may proceed to a pass state 1406 and return an indication that the insertion is verified. The indication that the insertion is verified may be returned to another process and / or may be used to prompt the sensor electronics to transition the analyte sensor system 1200 to an active mode by initiating a sensor session, as described herein. In one embodiment, multiple insertion conditions may need to be met for the insertion to be verified.

[0175] 15 is a state diagram illustrating one example of a workflow 1500 that may be performed by the sensor electronics 1202 of the analyte sensor system 1200 of FIG. 12 to perform a deployment test that tests the deployment of the analyte sensor 1206 using the wireless signal 1214 detected by the deployment sensor 1210. For example, workflow 1500 illustrates one exemplary way that the sensor electronics 1202 may perform all or a portion of operation 1304 of process flow 1300.

[0176] The workflow 1500 may detect when the wireless signal 1214 settles to a stable state and return an indication of whether the stable state of the wireless signal 1214 is a deployed state or a non-deployed state. If the wireless signal 1214 settles to a deployed state indicating sensor deployment, the workflow 1500 may result in a determination that the deployment verification has passed. On the other hand, if the wireless signal 1214 settles to a non-deployed state indicating no sensor deployment, the workflow 1500 may result in a determination that the deployment verification has failed.

[0177] In the start state 1502, the sensor electronics 1202 stores a start time and starts a stability timer. If it is not reset, the stability timer may run for a stability threshold time. For example, if the state of the wireless signal 1214 remains constant for the duration of the stability threshold time, it may indicate that the wireless signal 1214 is stable.

[0178] From the start state 1502, the sensor electronics 1202 may transition to a wait state 1506. In the wait state, the sensor electronics 1202 may continue to run a stability timer. In the wait state 1506, if there is no change in the state of the wireless signal 1214, the sensor electronics 1202 may continue to run the stability timer in the run state 1504. If the state of the wireless signal 1214 changes, the sensor electronics 1202 resets the stability timer and runs the timer in the run state 1504 after the reset.

[0179] Consider an example in which the wireless signal 1214 is generated by a transmitter on the applicator, such as transmitter 985 and / or transmitter 1112. Execution of workflow 1500 may have been prompted by detection of a test condition, such as an initial change in the state of the wireless signal 1214 to a deployed state and / or a change in the raw sensor signal. If the test condition was the result of actual insertion of the analyte sensor 1206, the transmitter may have changed the state of the wireless signal 1214 to the deployed state, and / or the applicator (including the transmitter) may have been physically removed from the vicinity of the analyte sensor system 1200, thereby affecting a permanent change in the state of the wireless signal 1214 to the deployed state. In this case, the state of the wireless signal 1214 may remain stable in the deployed state. On the other hand, if the test condition was caused by a temporary and / or external condition, the transmitter on the applicator may not have modified the state of the wireless signal 1214 to the deployed state, meaning that the wireless signal 1214 may oscillate and / or settle back to the non-deployed state.

[0180] If the state of the wireless signal 1214 remains stable for the duration of the stable time period (e.g., the stability timer expires without the state of the wireless signal 1214 changing), the sensor electronics 1202 may determine whether to proceed to a pass state 1508 and / or a fail state 1510 based, for example, on what state the wireless signal 1214 has settled into and, in some examples, whether a sufficient amount of time has passed since the workflow 1500 was started. For example, if the wireless signal 1214 is stable in a deployed state, the sensor electronics 1202 may determine whether more than a pass time period has elapsed since the stability timer was initially started at the start state 1502. If more than a pass time period has elapsed, the sensor electronics 1202 may return a validation of sensor deployment, stop the timer, and proceed to the pass state 1508.

[0181] In some examples, the passing time period is less than or equal to the stable time period, meaning that the workflow 1500 may return a verification of insertion whenever the wireless signal 1214 is stable in the deployed state. However, in various other examples, a different passing time period may be used, including a passing time period longer than the stable time period. For example, if the passing time period has not yet elapsed, the sensor electronics 1202 may remain in the wait state 1506 until the passing time period has elapsed and / or until a change in the state of the wireless signal 1214 occurs that prompts the sensor electronics 1202 to reset the stability timer.

[0182] If the state of the wireless signal 1214 remains stable for the duration of the stable time period during the non-deployment period, the sensor electronics 1202 may determine whether a failure time period has elapsed since the stability timer was first started at the start state 1502. In some examples, the failure time period may be longer than the stable time period. If the failure time period has not elapsed, the sensor electronics 1202 may return to the wait state 1506 until the failure time period has elapsed and / or until a change in the state of the wireless signal 1214 prompts the sensor electronics 1202 to reset the stability timer.

[0183] If the fail time period has elapsed, the sensor electronics may proceed to a fail state 1510. In the fail state 1510, the sensor electronics 1202 may return a fail of the insertion verification and stop the timer.

[0184] 16 is a state diagram illustrating an example workflow 1600 that may be performed by the sensor electronics 1202 to transition the analyte sensor system 1200 from a sleep mode to an active mode. In the example of FIG. 16, the sensor electronics 1202 verifies the deployment of the analyte sensor 1206 using an insertion test based on the raw sensor signal, e.g., as described with respect to FIG. 14, and a deployment test based on the wireless signal 1214, e.g., as described with respect to FIG. 15.

[0185] The sensor electronics 1202 may initially maintain the analyte sensor system 1200 in a sleep mode state 1602. If a test condition is met, the sensor electronics 1202 transitions to a start state 1606 where an insertion test and a deployment test are performed. In some embodiments, the insertion test and the deployment test are performed simultaneously. The test conditions may be, for example, as described herein with respect to operation 1302 of process flow 1300. If the deployment test fails while in the start state 1606, the sensor electronics 1202 may transition back to the sleep mode state 1602.

[0186] If the insertion test fails while in the start state 1606, the sensor electronics 1202 may transition to an insertion test fail state 1604. In the insertion test fail state 1604, the sensor electronics 1202 may continue to perform a deployment test and may also initiate a communication connection (e.g., a short-range wireless medium communication connection) with an external device, such as a user computing device 132, a peripheral medical device 122, or another external device. For example, the analyte sensor system 1200 may provide result data (e.g., an estimated analyte value) to the external device for display to a host or other user. In embodiments where the short-range wireless medium is a Bluetooth® or Bluetooth LE® medium, initiating the communication connection with the external device may include pairing the sensor electronics to the external device.

[0187] From the insertion test fail state 1604, if the deployment test failed, the sensor electronics 1202 may transition back to the sleep mode state 1602. From the insertion test fail state 1604, if the deployment test passed and / or if the sensor electronics 1202 successfully initiated a communication connection to an external device, the sensor electronics 1202 transitions to the insertion test fail state 1608. In some examples, the sensor electronics 1202 may continue to maintain or attempt a communication channel with the external device while in the insertion test fail state. For example, if a communication channel was successfully established, the sensor electronics 1202 may utilize the communication channel to report the insertion test failure to the external device.

[0188] From the start state 1606, if the insertion test passed, the sensor electronics may transition to an insertion test completed state 1612. In the insertion test completed state 1612, the sensor electronics 1202 may begin initiating a communication connection (e.g., a short-range wireless medium communication channel) with an external device and may begin acquiring data from the analyte sensor 1206. This may include, for example, recording the value of the raw sensor signal and / or processing the raw sensor signal to generate a corresponding estimated analyte value. From the insertion test completed state 1612, if the deployment test passed and / or a communication connection with an external device was established, the sensor electronics 1202 transitions to an active mode state 1614. In the active mode state 1614, the sensor electronics 1202 may operate the analyte sensor 1206 and the remainder of the analyte sensor system 1200 to capture and report estimated analyte values, as described herein.

[0189] If the deployment test fails from the insertion test complete state 1612, the sensor electronics 1202 may transition to a deployment test fail state 1616. In the deployment test fail state 1616, in some embodiments, the sensor electronics 1202 may continue to attempt a communication connection with the external device. For example, if a communication connection with the external device is successfully established, the sensor electronics 1202 may report a failure of the deployment test.

[0190] From the start state 1606, if the deployment test passes, the sensor electronics 1202 may transition to a deployment test complete 1610. In the deployment test complete state 1610, the sensor electronics 1202 may resume and / or otherwise continue the insertion test. If the insertion test fails from the deployment test complete state 1610, the sensor electronics may transition to an insertion test fail state 1608. If the insertion test passes from the deployment test complete state, the sensor electronics 1202 may transition to an active mode state 1614.

[0191] 17 is a state diagram illustrating another example workflow 1700 that may be executed by the sensor electronics 1202 to transition the analyte sensor system 1200 from a sleep mode to an active mode. In the example of FIG. 17, the sensor electronics 1202 verifies the deployment of the analyte sensor 1206 using a deployment test based on the wireless signal 1214, for example, as described with respect to FIG. 15, and a wake-up timer. For example, in the workflow 1700, it may be assumed that the analyte sensor 1206 has been inserted and the analyte sensor system 1200 is ready for a sensor session if more than a wake-up time period has elapsed since detection of the test condition.

[0192] The sensor electronics 1202 may initially maintain the analyte sensor system 1200 in a sleep mode state 1702. If a test condition is met, the sensor electronics 1202 transitions to a start state 1704 where a deployment test is performed. The test condition may be, for example, as described herein with respect to operation 1302 of process flow 1300. In some examples, upon detecting the test condition, the sensor electronics starts a wake-up timer. If the deployment test fails while in the start state 1704, the sensor electronics 1202 may transition back to the sleep mode state 1702.

[0193] If the wake-up timer completes from the start state 1704 (e.g., the wake-up time period elapses before the deployment test either passes or fails), the sensor electronics 1202 may transition to a timer completion state 1706. In the timer completion state 1706, the sensor electronics 1202 may continue with the deployment test and may also attempt a communications connection (e.g., a short-range wireless medium communications channel) with an external device and may begin acquiring data from the analyte sensor 1206. This may include, for example, recording values ​​of the raw sensor signals and / or processing the raw sensor signals to generate corresponding estimated analyte values.

[0194] From the timer completion state 1706, if the deployment test passed and / or a communication connection with an external device was established, the sensor electronics 1202 transitions to an active mode state 1710. In the active mode state 1710, the sensor electronics 1202 may operate the analyte sensor 1206 and the remainder of the analyte sensor system 1200 to capture and report estimated analyte values ​​as described herein. If the deployment test failed from the timer completion state 1706, the sensor electronics 1202 may transition to a fail state 1712. In the fail state 1712, the sensor electronics may continue to attempt a communication connection with an external device, for example, to report a failed deployment test.

[0195] From the start state 1704, if the deployment test passes, the sensor electronics 1202 may transition to a deployment test complete state 1708. In the deployment test complete state 1708, the sensor electronics 1202 may restart and / or otherwise continue the wake-up timer. When the wake-up timer completes (e.g., the wake-up time period has elapsed), the sensor electronics 1202 may transition to an active mode state 1710.

[0196] 18 is a block diagram illustrating a hardware architecture 1800 of a computing device in which a set or sequence of instructions may be executed to cause the machine to perform any one of the embodiments of the methods discussed herein. The hardware architecture 1800 may describe a variety of computing devices including, for example, sensor electronics 106, peripheral medical devices 122, smart devices 112, tablets 114, etc.

[0197] The architecture 1800 may operate as a stand-alone device or may be connected (e.g., networked) to other machines. In a network deployment, the architecture 1800 may operate in the capacity of either a server machine or a client machine in a server-client network environment, or function as a peer machine in a peer-to-peer (or distributed) network environment. The architecture 1800 may be implemented in a personal computer (PC), a tablet PC, a hybrid tablet, a set-top box (STB), a personal digital assistant (PDA), a mobile phone, a web appliance, a network router, a network switch, a network bridge, or any machine capable of executing instructions (sequential or otherwise) that specify operations to be performed by that machine.

[0198] An embodiment of the architecture 1800 includes a processor unit 1802 that includes at least one processor (e.g., a central processing unit (CPU), a graphics processing unit (GPU), or both, a processor core, a compute node). The architecture 1800 may further include a main memory 1804 and a static memory 1806 that communicate with each other via a link 1808 (e.g., a bus). The architecture 1800 may further include a video display unit 1810, an input device 1812 (e.g., a keyboard), and a UI navigation device 1814 (e.g., a mouse). In some embodiments, the video display unit 1810, the input device 1812, and the UI navigation device 1814 are incorporated into a touch screen display. The architecture 1800 may further include a storage device 1816 (e.g., a drive unit), a signal generating device 1818 (e.g., a speaker), a network interface device 1820, and one or more sensors (not shown), such as a Global Positioning System (GPS) sensor, a compass, an accelerometer, or another sensor.

[0199] In some embodiments, the processor unit 1802, or another suitable hardware component, may support hardware interrupts. In response to a hardware interrupt, the processor unit 1802 may, for example, suspend its processing and execute an ISR, as described herein.

[0200] Storage device 1816 includes machine-readable medium 1822 on which is stored one or more sets of data structures and instructions 1824 (e.g., software) that embody or are used in any one or more of the methods or functions described herein. Also, instructions 1824 may reside, completely or at least partially, within main memory 1804, static memory 1806, and / or processor unit 1802 during execution thereof by architecture 1800, with main memory 1804, static memory 1806, and processor unit 1802 also constituting machine-readable media.

[0201] Executable Instructions and Machine Storage Media Various memories (i.e., 1804, 1806, and / or memory of processor unit 1802) and / or storage devices 1816 may store one or more sets of instructions and data structures (e.g., instructions) 1824 that embody or are used by any one or more of the methods or functions described herein. These instructions, when executed by processor unit 1802, cause various operations to be performed to implement the disclosed embodiments.

[0202] As used herein, the terms "machine storage medium," "device storage medium," and "computer storage medium" (collectively referred to as "machine storage medium 1822") mean the same thing and may be used interchangeably in this disclosure. The term refers to single or multiple storage devices and / or media (e.g., centralized or distributed databases, and / or associated caches and servers) that store executable instructions and / or data, as well as cloud-based storage systems or storage networks that include multiple storage devices or devices. Thus, the term is intended to include, but is not limited to, solid-state memory, optical media, and magnetic media (including memory that is internal or external to the processor). Specific examples of machine, computer, and / or device storage media 1822 include non-volatile memory, examples of which include semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), FPGAs, and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The terms machine, computer, and device storage media 1822 specifically exclude carrier waves, modulated data signals, and other such media, at least some of which are covered by the term "signal media" discussed below.

[0203] signal medium The term "signal media" or "transmission media" shall include all forms of modulated data signals, carrier waves, etc. The term "modulated data signal" means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal.

[0204] Computer-Readable Medium The terms "machine-readable medium," "computer-readable medium," and "device-readable medium" mean the same thing and are used interchangeably in this disclosure. The term is defined to include both machine storage media and signal media. Thus, the term includes both storage devices / media and carrier wave / modulated data signals.

[0205] The instructions 1824 may be further transmitted or received over a communications network 1826 using a transmission medium via the network interface device 1820 using any one of a number of well-known transfer protocols (e.g., HTTP). Examples of communications networks include LANs, WANs, the Internet, cellular networks, plain old telephone service (POTS) networks, and wireless data networks (such as Wi-Fi, 3G, 4G LTE / LTE-A, 5G, or WiMAX networks). The term "transmission medium" is intended to include intangible media capable of storing, encoding, or carrying instructions for a machine to execute, as well as digital or analog communication signals or other intangible media for facilitating communication of such software.

[0206] Throughout this specification, multiple instances may practice components, operations, or structures that are described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed simultaneously, and there is no requirement that the operations be performed in the order illustrated. In the illustrated configurations, structures and functions presented as separate components may be implemented as combined structures or components. Similarly, structures and functions presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements are within the scope of the subject matter of this specification.

[0207] In this disclosure, various components are described as being configured in a particular manner. The components may be configured in any suitable manner. For example, a component that is or includes a computing device may be configured with suitable software instructions that program the computing device. The components may be configured by their hardware arrangement or in any other suitable manner.

[0208] The above description is intended to be illustrative, and not limiting. For example, the above-described embodiments (or one or more aspects thereof) can be used in combination with others. Other embodiments can be used by one of ordinary skill in the art upon reviewing the above description. The Abstract is intended to enable the reader to quickly ascertain the nature of the technical disclosure, e.g., in the United States, to comply with 37 CFR § 1.72(b). It is submitted with the understanding that it will not be used to interpret or limit the scope or spirit of the claims.

[0209] Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. However, the claims may not recite all of the features disclosed herein, since an embodiment may feature a subset of the features. Moreover, an embodiment may include fewer features than are disclosed in a particular embodiment. Accordingly, the following claims are incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. The scope of the embodiments disclosed herein should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0210] Each of these non-limiting examples in any part of the above description may stand alone or may be combined with one or more of the other examples in various permutations or combinations.

[0211] The above detailed description includes reference to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the subject matter may be practiced. These embodiments are also referred to herein as "examples." Such examples may include elements in addition to those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are provided. Furthermore, the inventors also contemplate examples using any combination or permutation of those elements (or one or more aspects thereof) shown or described with respect to a particular example (or one or more aspects thereof), or with respect to any other example (or one or more aspects thereof) shown or described herein.

[0212] In the event of a conflict of usage between this document and any document incorporated by reference, the usage in this document takes precedence.

[0213] In this document, the terms "a" or "an" are used to include one or more, as is common in patent documents, regardless of other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a non-exclusive, such that "A or B" includes "A but not B," "B but not A," "A and B," unless otherwise indicated. In this document, the terms "including" and "in which" are used as the plain English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, i.e., a system, device, article, composition, formulation, or process that includes elements in addition to those recited after such terms in a claim will still be deemed to be within the scope of that claim. Moreover, in the following claims, the terms "first," "second," "third," etc. are used merely as labels and are not intended to impose numerical requirements on their objects.

[0214] Geometric terms such as "parallel," "perpendicular," "circular," "square," and the like are not intended to require absolute mathematical precision unless the context dictates otherwise. Instead, such geometric terms allow for variations due to manufacturing or equivalent functions. For example, if an element is described as "circular" or "approximately circular," components that are not exactly round (e.g., those that are slightly elliptical or that are multi-sided polygons) are still encompassed by this description.

[0215] The method embodiments described herein may be at least partially implemented in a machine or computer. Some embodiments may include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform the methods described in the above embodiments. Implementations of such methods may include code, such as microcode, assembly language code, high-level language code, etc. Such code may include computer-readable instructions for performing various methods. This code may form part of a computer program product. Furthermore, in embodiments, the code may be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media may include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memory (RAM), read only memory (ROM), etc.

[0216] The above description is intended to be illustrative, not restrictive. For example, the above examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used, such as those by those of ordinary skill in the art upon reviewing the above description. The "Summary" is provided to enable the reader to quickly grasp the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or spirit of the claims. Also, in the above "Detailed Description," various features may be grouped together to streamline the disclosure. This should not be construed as intending that any unclaimed disclosed feature is essential to any claim. Rather, the subject matter of the invention may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are incorporated into the "Detailed Description" as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the subject matter should be determined with reference to the claims, along with the full scope of equivalents to which such claims are entitled. [Explanation of symbols]

[0217] 100 Environment 101 Host 102 Analyte Sensor System 104 Analyte Sensors 106 Sensor Electronics 108 Medical Devices 110 Radio communication signals 112 Handheld smart devices (e.g., smartphones) 114 tablets 116 Smart Pen 118 Computer 120 Wearable Devices 122 Peripheral medical devices 124 Network 126 Server systems (e.g., networked data centers) 128 Remote Terminal 130 Sensors 132 User Devices 136 Wearable Sensors 138 Wireless Access Point (WAP) 200 Medical Device Systems 202 Measurement circuit 204 Processor 206 Command 208 Memory 210 Data storage memory 212 Sensors 214 Battery 216 Recharging System 218 Wireless communication circuits 250 peripheral devices 252 UI 254 Memory Circuit 256 processors 258 Wireless communication circuits 260 Sensors 270 Medical Devices 272 UI 274 Memory Circuit 276 processors 278 Wireless communication circuits 280 Sensors 282 Treatment Circuit 290 units 292 Battery 294 Gate Circuit 302 Case 308 Adhesive Pad 334 Analyte Sensors 402 Case 408 Adhesive Pad 414 units 418 Electronic Equipment Unit 434 Analyte Sensors 532 Membrane Systems 534 Analyte Sensors 538 First Layer 539 Window 540 Second Layer 541 Conductors 542 Enzyme Domain 543 Third Layer 544 Diffusion Resistance Domain 546 Bioprotection Domain 547 Electrode layer 700 Sensor Circuit 704 Working electrode (WE) 706 Reference electrode (RE) 708 Double Layer Capacitance (Cdl) 710 Polarization Resistance (Rpol) 711 Internal Electronics (represented inside R Tx) 712 Analyte Sensor Membrane 928 Contact Part 985 Transmitter 1112 Transmitter 1200 Analyte Sensor System 1202 Sensor Electronics 1206 Analyte Sensors 1208 Battery 1210 Deployable Sensor 1212 Analog Front End 1214 Radio Signal 1216 NFC signal 1218 Short-range wireless communication medium 1220 Control circuit 1222 Temperature Sensor 1300 Process Flow 1400 Workflow 1402 Start state 1404 Failed state 1406 Passed status 1500 Workflows 1502 Start state 1504 Execution Status 1506 Waiting 1508 Passed status 1510 Failed condition 1600 Workflow 1602 Sleep mode state 1604 Insertion test failed condition 1606 Start state 1608 Insertion test failed condition 1610 Deployment test completed 1612 Insertion test completed 1614 Active mode state 1616 Deployment test failed 1700 Workflow 1702 Sleep mode state 1704 Start state 1706 Timer done status 1708 Deployment test completed 1710 Active mode state 1712 Failed state 1800 Hardware Architecture 1802 processor unit 1804 Main memory 1806 Static Memory 1808 Link 1810 Video Display Unit 1812 Input Devices 1814 UI navigation device 1816 Storage Devices 1818 Signal Generating Device 1820 Network Interface Device 1822 Machine-readable medium 1824 Data structures (e.g., instructions) 1826 Communication Networks

Claims

1. 1. A sensor system for in vivo use, the sensor system comprising: A sensor housing; an analyte sensor extending from the sensor housing; sensor electronics positioned within the sensor housing; The sensor electronics include: detecting a change in a wireless signal provided through the sensor housing from a first state to a second state; monitoring whether the wireless signal remains in the second state for at least a stability threshold time period after detecting that the wireless signal has changed from the first state to the second state; performing an action at the sensor system, the action being selected based at least in part on whether the wireless signal remains in the second state for at least the stability threshold time period; The sensor system is configured to perform operations including:

2. The sensor system of claim 1 , further comprising an applicator for inserting the analyte sensor under the skin of a host, the applicator comprising a transmitter, the transmitter generating the wireless signal.

3. The sensor system of claim 1 , further comprising a wireless signal sensor, the wireless signal sensor comprising at least one of a magnetic signal sensor, an inductive signal sensor, or an optical signal sensor.

4. Detecting that the wireless signal has changed from the first state to the second state includes: determining that the wireless signal is at least partially in the first state by determining that the wireless signal is present at a first time; determining, at a second time, that the wireless signal is at least partially in the second state by determining that the wireless signal is not present; and Including, The sensor system of claim 1 , wherein the second time is after the first time.

5. Detecting that the wireless signal has changed from the first state to the second state includes: determining, at a first time, that the wireless signal is at least partially in the first state by determining that the wireless signal has a first magnetic polarity; determining, at a second time, that the wireless signal is at least partially in the second state by determining that the wireless signal has a second magnetic polarity different from the first magnetic polarity; Including, The sensor system of claim 1 , wherein the second time is after the first time.

6. 2. The sensor system of claim 1, wherein determining whether the wireless signal remains in the second state for at least the stability threshold time period comprises determining that the wireless signal remains in the second state for at least the stability threshold time period, and the action comprises determining an estimated analyte value for a host using a sensor output produced by the analyte sensor.

7. 2. The sensor system of claim 1, wherein the operations further include determining that the sensor electronics have established a communication connection with an external device before the wireless signal remains in the second state for at least the stability threshold time period, and the action includes determining an estimated analyte value for a host using a sensor output generated by the analyte sensor.

8. 2. The sensor system of claim 1, wherein the operations further include, after detecting that the wireless signal has changed from the first state to the second state, determining that the wireless signal has remained in the first state for more than the stability threshold time period, and the action includes configuring the sensor system into a sleep mode.

9. The sensor system of claim 1 , wherein the operations further comprise determining that an activation time period has elapsed since detecting that the wireless signal changed from the first state to the second state.

10. 2. The sensor system of claim 1, wherein the operations further include determining that more than a failure threshold time period has elapsed since detecting that the wireless signal changed from the first state to the second state, the failure threshold time period being greater than the stability threshold time period.

11. The operation includes: determining that an activation threshold time period has elapsed since detecting that the wireless signal has changed from the first state to the second state; determining that the wireless signal has remained in the first state for more than the stability threshold time period; Further comprising: The sensor system of claim 1 , wherein the action includes configuring the sensor system into a failing state.

12. The operation includes: determining that a wake-up threshold time period has elapsed since detecting a change of the wireless signal from the first state to the second state and determining that the wireless signal has not remained in either the first state or the second state for more than the stability threshold time period; Initiating a communication connection with an external device; The sensor system of claim 1 further comprising:

13. 13. The sensor system of claim 12, wherein the operation further comprises determining that the sensor electronics has established the communication connection with the external device, and the action comprises determining an estimated analyte value for a host using a sensor output produced by the analyte sensor.

14. The sensor system of claim 1 , wherein the operation further comprises determining that a sensor output produced by the analyte sensor satisfies a first insertion condition.

15. The operation includes: after determining that the sensor output satisfies the first insertion condition, initiating a communication connection with an external device; determining that the sensor electronics has established the communication connection with the external device; Further comprising: The sensor system of claim 14 , wherein the action includes determining an estimated analyte value for a host using a sensor output produced by the analyte sensor.

16. 1. A method for operating an analyte sensor system including an in vivo analyte sensor, the method comprising: detecting, by sensor electronics of the analyte sensor system, that a wireless signal provided to the sensor electronics through a sensor housing of the analyte sensor system changes from a first state to a second state; monitoring, by the sensor electronics, whether the wireless signal remains in the second state for at least a stability threshold time period after detecting that the wireless signal has changed from the first state to the second state; performing, by the sensor electronics, an action at the analyte sensor system, selected based at least in part on whether the wireless signal remains in the second state for at least the stability threshold time period; A method comprising:

17. 17. The method of claim 16, further comprising receiving the wireless signal by the sensor electronics and from a transmitter, the transmitter being positioned in an applicator for inserting an analyte sensor of the analyte sensor system under the skin of a host.

18. The method of claim 16 , further comprising receiving the wireless signal using at least one of a magnetic signal sensor, an inductive signal sensor, or an optical signal sensor.

19. Detecting that the wireless signal has changed from the first state to the second state includes: determining that the wireless signal is at least partially in the first state by determining that the wireless signal is present at a first time; determining, at a second time, that the wireless signal is at least partially in the second state by determining that the wireless signal is not present; and Including, The method of claim 16 , wherein the second time is after the first time.

20. Detecting that the wireless signal has changed from the first state to the second state includes: determining, at a first time, that the wireless signal is at least partially in the first state by determining that the wireless signal has a first magnetic polarity; determining, at a second time, that the wireless signal is at least partially in the second state by determining that the wireless signal has a second magnetic polarity different from the first magnetic polarity; Including, The method of claim 16 , wherein the second time is after the first time.

21. 17. The method of claim 16, wherein determining whether the wireless signal remains in the second state for at least the stability threshold time period comprises determining that the wireless signal remains in the second state for at least the stability threshold time period, and the action comprises determining an estimated analyte value for a host using a sensor output produced by an analyte sensor of the analyte sensor system.

22. 17. The method of claim 16, further comprising determining that the sensor electronics has established a communication connection with an external device before the wireless signal remains in the second state for at least the stability threshold time period, and the action includes determining an estimated analyte value for a host using a sensor output produced by an analyte sensor of the analyte sensor system.

23. 17. The method of claim 16, further comprising, after detecting the wireless signal changing from the first state to the second state, determining that the wireless signal remained in the first state for more than the stability threshold time period, and wherein the action includes configuring the analyte sensor system into a sleep mode.

24. 17. The method of claim 16, further comprising determining that an wake-up time period has elapsed since detecting that the wireless signal changed from the first state to the second state.

25. 17. The method of claim 16, further comprising determining that more than a failure threshold time period has elapsed since detecting that the wireless signal changed from the first state to the second state, the failure threshold time period being greater than the stability threshold time period.

26. determining that an activation threshold time period has elapsed since detecting that the wireless signal has changed from the first state to the second state; determining that the wireless signal has remained in the first state for more than the stability threshold time period; Further comprising: The method of claim 16 , wherein the action comprises configuring the analyte sensor system to a fail state.

27. determining that a wake-up threshold time period has elapsed since detecting a change of the wireless signal from the first state to the second state and determining that the wireless signal has not remained in either the first state or the second state for more than the stability threshold time period; Initiating a communication connection with an external device; The method of claim 16 further comprising:

28. 30. The method of claim 27, further comprising determining that the sensor electronics has established the communication connection with the external device, and the action includes determining an estimated analyte value for a host using a sensor output produced by an analyte sensor of the analyte sensor system.

29. 17. The method of claim 16, further comprising determining that a sensor output produced by an analyte sensor of the analyte sensor system satisfies a first insertion condition.

30. after determining that the sensor output satisfies the first insertion condition, initiating a communication connection with an external device; determining that the sensor electronics has established the communication connection with the external device; Further comprising:

30. The method of claim 29, wherein the action includes determining an estimated analyte value for a host using a sensor output produced by the analyte sensor.

31. A non-transitory machine-readable medium comprising instructions that, when executed by an analyte sensor system, cause the analyte sensor system to: detecting a change in a wireless signal provided through a sensor housing of the analyte sensor system to sensor electronics of the analyte sensor system from a first state to a second state; monitoring whether the wireless signal remains in the second state for at least a stability threshold time period after detecting that the wireless signal has changed from the first state to the second state; performing an action at the analyte sensor system, the action being selected based at least in part on whether the wireless signal remains in the second state for at least the stability threshold time period; A medium for performing an operation including:

32. 32. The medium of claim 31 , wherein the actions further include receiving the wireless signal from a transmitter, the transmitter positioned in an applicator for inserting an analyte sensor of the analyte sensor system under the skin of a host.

33. 32. The medium of claim 31, wherein the actions further include receiving the wireless signal using at least one of a magnetic signal sensor, an inductive signal sensor, or an optical signal sensor.

34. Detecting that the wireless signal has changed from the first state to the second state includes: determining that the wireless signal is at least partially in the first state by determining that the wireless signal is present at a first time; determining, at a second time, that the wireless signal is at least partially in the second state by determining that the wireless signal is not present; and Including, 32. The medium of claim 31, wherein the second time is after the first time.

35. Detecting that the wireless signal has changed from the first state to the second state includes: determining, at a first time, that the wireless signal is at least partially in the first state by determining that the wireless signal has a first magnetic polarity; determining, at a second time, that the wireless signal is at least partially in the second state by determining that the wireless signal has a second magnetic polarity different from the first magnetic polarity; Including, 32. The medium of claim 31, wherein the second time is after the first time.

36. 32. The medium of claim 31 , wherein determining whether the wireless signal remains in the second state for at least the stability threshold time period comprises determining that the wireless signal remains in the second state for at least the stability threshold time period, and the action comprises determining an estimated analyte value for a host using a sensor output generated by an analyte sensor of the analyte sensor system.

37. 32. The medium of claim 31 , wherein the operations further include determining that the sensor electronics of the analyte sensor system have established a communication connection with an external device before the wireless signal remains in the second state for at least the stability threshold time period, and the action includes determining an estimated analyte value for a host using a sensor output generated by an analyte sensor of the analyte sensor system.

38. 32. The medium of claim 31 , wherein the operations further include, after detecting that the wireless signal has changed from the first state to the second state, determining that the wireless signal has remained in the first state for more than the stability threshold time period, and the action includes configuring the analyte sensor system into a sleep mode.

39. 32. The medium of claim 31, wherein the actions further include determining that an active time period has elapsed since detecting that the wireless signal changed from the first state to the second state.

40. 32. The medium of claim 31 , wherein the operations further include determining that more than a failure threshold time period has elapsed since detecting that the wireless signal changed from the first state to the second state, the failure threshold time period being greater than the stability threshold time period.

41. The operation includes: determining that an activation threshold time period has elapsed since detecting that the wireless signal has changed from the first state to the second state; determining that the wireless signal has remained in the first state for more than the stability threshold time period; Further comprising:

32. The medium of claim 31, wherein the action comprises configuring the analyte sensor system to a fail state.

42. The operation includes: determining that a wake-up threshold time period has elapsed since detecting a change of the wireless signal from the first state to the second state and determining that the wireless signal has not remained in either the first state or the second state for more than the stability threshold time period; Initiating a communication connection with an external device; The medium of claim 31 further comprising:

43. 43. The medium of claim 42, wherein the operation further comprises determining that the sensor electronics of the analyte sensor system have established the communication connection with the external device, and the action comprises determining an estimated analyte value for a host using a sensor output produced by the analyte sensor.

44. 32. The medium of claim 31, wherein the action further comprises determining that a sensor output produced by an analyte sensor of the analyte sensor system satisfies a first insertion condition.

45. The operation includes: after determining that the sensor output satisfies the first insertion condition, initiating a communication connection with an external device; determining that the sensor electronics of the analyte sensor system has established the communication connection with the external device; Further comprising:

45. The medium of claim 44, wherein the action includes determining an estimated analyte value for a host using a sensor output produced by the analyte sensor.

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