System, device and method for sensor fault detection

Abstract

Various embodiments of systems, devices, and methods for detecting sensor failure in an analyte sensor are disclosed. These embodiments utilize analyte metrics and thresholds.

Description

Technical Field

[0001] The subject matter described herein relates generally to systems, apparatus, and methods for sensor fault detection. Background Art

[0002] There is a large and growing market for monitoring the health and condition of humans and other living animals. Information describing a person's physical or physiological condition can be used in countless ways to assist and improve quality of life, as well as to diagnose and treat adverse human conditions.

[0003] Common devices used to collect such information are physiological sensors, such as biochemical analyte sensors, or devices capable of sensing chemical analytes of biological entities. Biochemical sensors come in a variety of forms and can be used to sense analytes in fluids, tissues, or gases that form part of or are produced by a biological entity, such as a human being. These analyte sensors can be used on or within the body itself, or on biological matter that has been removed from the body.

[0004] Although analyte sensors often have complex and well-studied designs, they may still suffer unexpected loss of functionality before the end of their expected lifetime. For example, in some instances, moisture ingress into the sealed portion of an on-body sensor unit of an analyte monitoring system can cause a disruption in the sensor's electrical signal path. This can result in one or more of the following: intermittent spikes, data that fails existing data quality checks, high instantaneous analyte change rates observed, or very high analyte level readings.

[0005] Certain known methods can detect and remove some of these artifacts and prevent them from affecting the final analyte level reading displayed by the analyte monitoring system. However, these existing methods may not prevent all situations. If these known methods fail to detect these artifacts, the consequences may be harmful to the patient. For example, an artifact that inaccurately reflects a high analyte level reading may mislead the patient to erroneously administer or increase the dosage of a medication.

[0006] For these and other reasons, there is a need for improved detection of sensor failure in analyte sensors. Summary of the invention

[0007] Example embodiments of systems, apparatus, and methods for fault detection in analyte sensors are described herein. These embodiments provide sensor fault detection based on one or more calculated metrics and one or more thresholds based on the calculated metrics. According to some embodiments, for example, an indication of a suspected sensor fault may be generated when a predetermined analyte level rate of change threshold and a predetermined analyte level sum threshold are exceeded. Numerous examples of algorithms and methods for performing combinations and / or variations of one or both of these detection mechanisms, as well as example embodiments of systems and apparatus for performing the same are provided.

[0008] Other systems, devices, methods, features, and advantages of the subject matter described herein will be apparent to those skilled in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included in this specification, be within the scope of the subject matter described herein, and be protected by the accompanying claims. Features of the example embodiments should in no way be construed as limiting the appended claims without explicitly stating those features in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The details of the structure and operation of the subject matter set forth herein will become apparent by studying the accompanying drawings, wherein like reference numerals refer to like parts. The components in the drawings are not necessarily drawn to scale, with emphasis placed on illustrating the principles of the subject matter. Moreover, all illustrations are intended to convey concepts, wherein relative sizes, shapes, and other detailed attributes may be shown schematically rather than literally or precisely.

[0010] Figure 1 is an illustrative diagram depicting an example implementation of an in vivo analyte monitoring system.

[0011] Figure 2 is a block diagram of an example implementation of a reader device.

[0012] Figure 3 is a block diagram of an example implementation of a sensor control device.

[0013] Figure 4 is a graph depicting an example of analyte measurements over time.

[0014] Figure 5 is a flow chart depicting an example implementation of a method for fault detection in an analyte sensor. DETAILED DESCRIPTION

[0015] Before describing the present subject matter in detail, it should be understood that the present disclosure is not limited to the specific embodiments described, as such embodiments may of course vary. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention, as the scope of the present disclosure will be limited only by the appended claims.

[0016] The publications discussed herein are provided only for their disclosure prior to the filing date of the present application. Nothing herein should be construed as admitting that the present disclosure is not entitled to predate such publications by virtue of prior disclosure. In addition, the publication date provided may differ from the actual publication date, which may require independent confirmation.

[0017] In general, embodiments of the present disclosure are used with systems, devices, and methods for detecting at least one analyte (e.g., glucose) in a body fluid (e.g., interstitial fluid ("ISF") or blood, subcutaneous or dermal fluid in the dermis, or otherwise). Thus, many embodiments include an in vivo analyte sensor that is structurally configured such that at least a portion of the sensor is positioned or positionable within a user's body to obtain information about at least one analyte in the body. However, embodiments disclosed herein are used with in vivo analyte monitoring systems that incorporate in vitro capabilities, as well as purely in vitro or ex vivo analyte monitoring systems, including those that are completely non-invasive.

[0018] In addition, for each embodiment of the method disclosed herein, systems and devices capable of performing each of those embodiments are covered within the scope of the present disclosure. For example, embodiments of sensor control devices are disclosed, and these devices may have one or more sensors, analyte monitoring circuits (e.g., analog circuits), non-transitory memory (e.g., for storing instructions), power supplies, communication circuits, transmitters, receivers, processing circuits and / or controllers (e.g., for executing instructions), which can perform any and all method steps, or help perform any and all method steps. These sensor control device embodiments can be used and can be used to implement those steps performed by the sensor control device according to any and all methods described herein.

[0019] Likewise, embodiments of reader devices are disclosed that have one or more transmitters, receivers, non-transitory memory (e.g., for storing instructions), power supplies, processing circuitry, and / or controllers (e.g., for executing instructions) that can perform any and all method steps, or facilitate the performance of any and all method steps. Embodiments of these reader devices can be used to implement those steps performed by the reader device according to any and all methods described herein.

[0020] Implementations of trusted computer systems are also disclosed. These trusted computer systems may include one or more processing circuits, controllers, transmitters, receivers, non-transitory memories, databases, servers, and / or networks, and may be dispersed across multiple geographic regions. These implementations of trusted computer systems may be used to implement the steps performed by the trusted computer system according to any and all methods described herein.

[0021] Many embodiments of the present disclosure are directed to improving the computer-implemented capabilities of analyte monitoring systems in detecting suspected sensor failures. For example, in some embodiments, a sensor control device is worn on the body, wherein the sensor control device includes an in vivo analyte sensor. According to one aspect of this embodiment, sensor data received from the analyte sensor can be periodically received, and an analyte metric can be calculated by a processing circuit of the sensor control device. For example, the analyte metric can include a rate of change of analyte levels and / or a sum of analyte levels within a predetermined time window. Based on the analyte metric, the processing circuit can detect a suspected sensor failure in the analyte sensor.

[0022] Therefore, the embodiments disclosed herein reflect improvements over existing methods of sensor fault detection. For example, these embodiments can provide a more robust sensor fault detection method by utilizing multiple threshold conditions to reduce the number of false positives. Therefore, the embodiments described herein are directed to systems, devices, and methods that can improve the accuracy of analyte monitoring systems by utilizing analyte sensor data in specific and unconventional ways and by promptly notifying a user when a suspected sensor fault is detected and / or when the analyte sensor should be replaced. Other features and advantages of the disclosed embodiments are discussed further below.

[0023] However, before describing the embodiments in detail, it is first necessary to describe examples of devices that may be present in, for example, an in vivo analyte monitoring system, as well as examples of their operation, all of which may be used with the embodiments described herein.

[0024] Example Implementations of Analyte Monitoring Systems

[0025] There are various types of analyte monitoring systems. For example, a "continuous analyte monitoring" system (or "continuous glucose monitoring" system) is an in vivo system that can repeatedly or continuously send data from a sensor control device to a reader device without prompting, such as automatically sending according to a schedule. As another example, a "rapid analyte monitoring" system (or "rapid glucose monitoring" system or simply "rapid" system) is an in vivo system that can transmit data from a sensor control device in response to a reader device request for a scan or data, such as using near field communication (NFC) or radio frequency identification (RFID) protocols. In vivo analyte monitoring systems can also operate without the need for finger stick calibration.

[0026] The in vivo monitoring system may include a sensor that contacts the user's bodily fluids when positioned in the body and senses the level of one or more analytes contained therein. The sensor may be part of a sensor control device that resides on the user's body and includes electronics and a power source that enable and control analyte sensing. The sensor control device and its variations may also be referred to as a "sensor control unit," an "on-body electronics" device or unit, an "on-body" device or unit, or a "sensor data communication" device or unit, and the like. As used herein, these terms are not limited to devices with analyte sensors, but include devices with other types of sensors, whether biometric or non-biometric. The term "on-body" refers to any device located directly on or in close proximity to the body, such as a wearable device (e.g., glasses, watches, wristbands or bracelets, neckbands or necklaces, etc.).

[0027] The in vivo monitoring system may also include one or more reader devices that receive sensed analyte data from the sensor control device. These reader devices can process and / or display sensed analyte data or sensor data to the user in any number of forms. These and their variants may be referred to as "handheld reader devices", "reader devices" (or simply "readers"), "handheld electronic devices" (or handheld devices), "portable data processing" devices or units, "data receivers", "receiver" devices or units (or simply receivers), "relay" devices or units or "remote" devices or units, etc. Other devices such as personal computers have also been used or incorporated with in vivo and in vitro monitoring systems.

[0028] In vivo analyte monitoring systems can be distinguished from "in vitro" systems, which contact biological samples outside the body (or more precisely "ex vivo") and generally include a meter device having a port for receiving an analyte test strip carrying a user's bodily fluid, which can be analyzed to determine the user's analyte level. As described above, the embodiments described herein can be used with in vivo systems, in vitro systems, and combinations thereof.

[0029] Embodiments described herein can be used to monitor and / or process information about any number of one or more different analytes. Analytes that can be monitored include, but are not limited to, acetylcholine, amylase, bilirubin, cholesterol, chorionic gonadotropin, glycosylated hemoglobin (HbA1c), creatine kinase (e.g., CK-MB), creatine, creatinine, DNA, fructosamine, glucose, glucose derivatives, glutamine, growth hormone, hormones, ketones, ketone bodies, lactic acid, peroxides, prostate-specific antigen, prothrombin, RNA, thyroid stimulating hormone, and troponin. The concentration of drugs can also be monitored, such as antibiotics (e.g., gentamicin, vancomycin, etc.), digitoxin, digoxin, drugs of abuse, theophylline, and warfarin. In embodiments where more than one analyte is monitored, the analytes can be monitored at the same or different times.

[0030] Figure 1 is an illustrative diagram depicting an example embodiment of an in vivo analyte monitoring system 100 having a sensor control device 102 and a reader device 120 that communicate with each other via a local communication path (or link) 140, which may be wired or wireless and may be unidirectional or bidirectional. In embodiments where path 140 is wireless, near field communication (NFC) protocols, RFID protocols, Bluetooth or Bluetooth low energy protocols, Wi-Fi protocols, proprietary protocols, etc. may be used, including those communication protocols existing as of the filing date or variants subsequently developed thereof.

[0031] The reader device 120 is also capable of wired, wireless, or combined communication with a computer system 170 (e.g., a local or remote computer system) via a communication path (or link) 141 and with a network 190 (e.g., the Internet or the cloud) via a communication path (or link) 142. Communication with the network 190 may involve communication with a trusted computer system 180 within the network 190, or communication with the computer system 170 via the network 190 via a communication link (or path) 143. The communication paths 141, 142, and 143 may be wireless, wired, or both, may be unidirectional or bidirectional, and may be a telecommunications network, such as a Wi-Fi network, a local area network (LAN), a wide area network (WAN), the Internet, or other data network. In some cases, the communication paths 141 and 142 may be the same path. All communications on paths 140, 141, and 142 may be encrypted, and sensor control device 102, reader device 120, computer system 170, and trusted computer system 180 may be configured to encrypt and decrypt those communications that are sent and received, respectively.

[0032] Variations of devices 102 and 120 , as well as other components of in vivo based analyte monitoring systems suitable for use with the system, device, and method embodiments described herein, are described in US Patent Application Publication No. 2011 / 0213225 (the '225 publication), which is incorporated herein by reference for all purposes.

[0033] The sensor control device 102 may include a housing 103, which includes an in vivo analyte monitoring circuit and a power supply. In this embodiment, the in vivo analyte monitoring circuit is electrically coupled to an analyte sensor 104, which extends through an adhesive patch 105 and extends from the housing 103. The adhesive patch 105 includes an adhesive layer (not shown) for attachment to the skin surface of the user's body. In addition to or in place of an adhesive, other forms of attachment to the body can be used.

[0034] Sensor 104 is suitable for at least partially inserting into the user's body, where it can be in fluid contact with the user's body fluid (e.g., subcutaneous (subcutaneous) fluid, dermal fluid or blood), and can be used together with an in vivo analyte monitoring circuit to measure the user's analyte-related data. Sensor 104 and any accompanying sensor control electronics can be applied to the body in any desired manner. For example, an insertion device (not shown) can be used to position all or part of the analyte sensor 104 through the outer surface of the user's skin and contact it with the user's body fluid. In the process of doing so, the insertion device can also position the sensor control device 102 with an adhesive patch 105 on the skin. In other embodiments, the insertion device can first position the sensor 104, and then the accompanying sensor control electronics can be manually or mechanically coupled to the sensor 104. Examples of insertion devices are described in U.S. Patent Publication Nos. 2008 / 0009692, 2011 / 0319729, 2015 / 0018639, 2015 / 0025345, and 2015 / 0173661, all of which are incorporated herein by reference for all purposes.

[0035] After collecting the raw data from the user's body, the sensor control device 102 can apply analog signal conditioning to the data and convert the data into a digital form of the conditioned raw data. In some embodiments, the sensor control device 102 can then process the digital raw data into a form representing the measured biometrics (e.g., analyte levels) of the user and / or one or more analyte metrics based thereon through an algorithm. For example, the sensor control device 102 may include processing circuitry to calculate an analyte metric used by an analyte sensor to detect a sensor failure through an algorithm executing any one of the method steps described herein. The sensor control device 102 can then encode and wirelessly transmit the calculated analyte metric, an indication of a sensor failure, and / or processed sensor data to a reader device 120, which encodes and wirelessly transmits the data to the reader device 120, which in turn can format or graphically process the received data for digital display to the user. In other embodiments, in addition to, or in lieu of, wirelessly communicating the sensor data to another device (e.g., reader device 120), the sensor control device 102 may graphically process the data in a final form to make it ready for display, and display the data on a display of the sensor control device 102. In some embodiments, the system uses the final form of the biometric data (before graphical processing) (e.g., for incorporation into a diabetes monitoring protocol) without processing for display to a user.

[0036] In other embodiments, the conditioned raw digital data may be encoded for transmission to another device, such as a reader device 120, which then processes the digital raw data algorithmically into a form representative of the user's measured biometric characteristic (e.g., a form that is easily made suitable for display to the user) and / or one or more analyte metrics based thereon. The reader device 120 may include processing circuitry to algorithmically perform any of the method steps described herein to calculate an analyte metric for detecting a fault in an analyte sensor. The algorithmically processed data may then be formatted or graphically processed for digital display to the user.

[0037] In some embodiments, the sensor control device 102 and the reader device 120 send the digital raw data to another computer system for algorithmic processing and display.

[0038] The reader device 120 may include a display 122 to output information to a user and / or accept input from a user, and an optional input component 121 (or more), such as a button, actuator, touch-sensitive switch, capacitive switch, pressure-sensitive switch, scroll wheel, etc., to input data, commands, or otherwise control the operation of the reader device 120. In some embodiments, the display 122 and the input component 121 may be integrated into a single component, for example, where the display can detect the presence and location of physical contact on the display, such as through a touch screen user interface. In some embodiments, the input component 121 of the reader device 120 may include a microphone, and the reader device 120 may include software configured to analyze audio input received from the microphone so that the functions and operations of the reader device 120 can be controlled by voice commands. In some embodiments, the output component of the reader device 120 includes a speaker (not shown) for outputting information as audible signals. Similar voice response components, such as a speaker, microphone, and software routines for generating, processing, and storing voice-driven signals, may be included in the sensor control device 102.

[0039] The reader device 120 may also include one or more data communication ports 123 for wired data communication with an external device such as a computer system 170 or a sensor control device 102. Example data communication ports include a USB port, a mini USB port, a USB Type-C port, a USB micro A and / or micro B port, an RS-232 port, an Ethernet port, a Firewire port, or other similar data communication ports configured to connect to a compatible data cable. The reader device 120 may also include an integrated or attachable in vitro blood glucose meter including an in vitro test strip port (not shown) to receive an in vitro glucose test strip for performing in vitro blood glucose measurements.

[0040] The reader device 120 may display the measured biometric data wirelessly received from the sensor control device 102, and may also be configured to output alarms, alarm notifications, glucose values, etc., which may be visual, audible, tactile, or any combination thereof. Further details and other display embodiments may be found, for example, in U.S. Patent Publication 2011 / 0193704, which is incorporated herein by reference in its entirety for all purposes.

[0041] The reader device 120 may be used as a data conduit to transmit measured data and / or analyte metrics from the sensor control device 102 to the computer system 170 or the trusted computer system 180. In certain embodiments, data received from the sensor control device 102 may be stored (permanently or temporarily) in one or more memories of the reader device 120 before being uploaded to the systems 170, 180 or the network 190.

[0042] The computer system 170 may be a personal computer, a server terminal, a laptop computer, a tablet computer, or other suitable data processing device. The computer system 170 may be (or include) software for data management and analysis and for communicating with components in the analyte monitoring system 100. The computer system 170 may be used by a user or a medical professional to display and / or analyze biometric data measured by the sensor control device 102. In some embodiments, the sensor control device 102 may transmit the biometric data directly to the computer system 170 without an intermediary such as a reader device 120, or transmit indirectly using an Internet connection (or optionally without first sending to the reader device 120). The operation and use of the computer system 170 are further described in the '225 publication incorporated herein. The analyte monitoring system 100 may also be configured for use with a data processing module (not shown), also as described in the incorporated '225 publication.

[0043] The trusted computer system 180 may be physically or virtually owned by a manufacturer or distributor of the sensor control device 102 via a secure connection and may be used to perform authentication of the sensor control device 102, to securely store a user's biometric data, and / or to serve as a server that provides services to a data analysis program (e.g., accessible via a web browser) to perform analysis of the user's measurement data.

[0044] Example Implementation of a Reader Device

[0045] The reader device 120 may be a mobile communication device, such as a dedicated reader device (configured to communicate with the sensor control device 102 and optionally with the computer system 170, but without mobile phone communication capabilities), or a mobile phone, including but not limited to a Wi-Fi or Internet-enabled smart phone, tablet computer, or personal digital assistant (PDA). Examples of smart phones may include Operating system, Android TM operating system, operating system, WebOS TM , Operating system or Those mobile phones that have a data network connection capability for data communications via an Internet connection and / or a Local Area Network (LAN).

[0046] The reader device 120 may also be configured as a mobile smart wearable electronic assembly, such as an optical assembly worn above or near the user's eyes (e.g., smart lenses or smart glasses such as Google Glass as a mobile communication device). The optical assembly may have a transparent display that displays information about the user's analyte level to the user (as described herein) while allowing the user to see through the display so that the user's overall vision is minimally obstructed. The optical assembly may be capable of wireless communication like a smartphone. Other examples of wearable electronic devices include devices worn around or near a user's wrist (e.g., a watch, etc.), neck (e.g., a necklace, etc.), head (e.g., a headband, a hat, etc.), chest, etc.

[0047] Figure 2 1 is a block diagram of an example implementation of a reader device 120 configured as a smartphone. Here, the reader device 120 includes an input component 121, a display 122, and processing circuitry 206, which may include one or more processors, microprocessors, controllers, and / or microcontrollers, each of which may be a discrete chip or distributed among (or part of) multiple different chips. Here, the processing circuitry 206 includes a communication processor 202 with onboard memory 203 and an application processor 204 with onboard memory 205. The reader device 120 further includes an RF communication circuit 208 coupled to an RF antenna 209, a memory 210, a multifunction circuit 212 with one or more associated antennas 214, a power supply 216, a power management circuit 218, and a clock 219. Figure 2 is a simplified representation of typical hardware and functionality residing within a smartphone, and one of ordinary skill in the art will readily recognize that other hardware and functionality (eg, codecs, drivers, glue logic) may also be included.

[0048] The communication processor 202 may interface with the RF communication circuit 208 and perform analog-to-digital conversion, encoding and decoding, digital signal processing, and other functions that help convert voice, video, and data signals into a format suitable for providing to the RF communication circuit 208 (e.g., in-phase and quadrature), which may then transmit the signals wirelessly. The communication processor 202 may also interface with the RF communication circuit 208 to perform the reverse functions required to receive wireless transmissions and convert them into digital data, voice, and video. The RF communication circuit 208 may include a transmitter and a receiver (e.g., integrated as a transceiver) and associated encoder logic.

[0049] The application processor 204 may be adapted to execute an operating system and any software applications resident on the reader device 120, process video and graphics, and perform those other functions not related to the processing of communications sent and received via the RF antenna 209. The smartphone operating system will run along with many applications on the reader device 120. Any number of applications (also referred to as "user interface applications") may be running on the reader device 120 at any time, and may include one or more applications related to the diabetes monitoring regimen, in addition to other common applications not related to the regimen, such as email, calendar, weather, sports, games, etc. For example, data indicative of detected analyte levels and in vitro blood analyte measurements received by the reader device may be securely communicated to the user interface application in the memory 210 of the reader device 120. Such communications may be securely performed, for example, by using mobile application containerization or packaging techniques.

[0050] The memory 210 may be shared by one or more of the various functional units present in the reader device 120, or may be distributed among two or more of them (e.g., as separate memories present in different chips). The memory 210 may also be its own separate chip. The memories 203, 205, and 210 are non-transitory and may be volatile (e.g., RAM, etc.) and / or non-volatile memory (e.g., ROM, flash memory, F-RAM, etc.).

[0051] The multi-function circuit 212 may be implemented as one or more chips and / or components (e.g., transmitters, receivers, transceivers, and / or other communication circuits) that perform other functions, such as local wireless communication with, for example, the sensor control device 102 under an appropriate protocol (e.g., Wi-Fi, Bluetooth, Bluetooth low energy, near field communication (NFC), radio frequency identification (RFID), proprietary protocols, etc.) and determining the geographic location of the reader device 120 (e.g., global positioning system (GPS) hardware). One or more other antennas 214 are associated with the functional circuit 212 as needed to operate with various protocols and circuits.

[0052] The power source 216 may include one or more batteries, which may be rechargeable batteries or disposable batteries for one-time use. The power management circuit 218 may regulate battery charging and power monitoring, boost power, perform DC conversion, and the like.

[0053] The reader device 120 may also include a drug (e.g., insulin, etc.) delivery device or be integrated with it so that they, for example, share a common housing. Examples of such drug delivery devices may include a drug pump with a cannula left in the body to allow infusion over a period of hours or days (e.g., a wearable pump for delivering basal insulin and a large dose of insulin). When combined with a drug pump, the reader device 120 may include a reservoir for storing drugs, a pump that can be connected to a delivery tube, and an infusion cannula. The pump can press the drug out of the reservoir through a cannula inserted therein and enter the diabetic body through a catheter. Other examples of drug delivery devices that can be included with the reader device 120 (or integrated with it) include a portable injection device that only pierces the skin each time it is delivered and is then removed (e.g., an insulin pen). When the reader device 120 is combined with a portable injection device, it may include an injection needle, a cartridge for accommodating drugs, an interface for controlling the amount of drugs to be delivered, and an actuator for causing injection. The device can be reused until the drug is exhausted, at which time the combination device can be discarded, or the cartridge can be replaced with a new cartridge, at which time the combination device can be reused. The needle can be replaced after each injection.

[0054] The combined device can be used as part of a closed loop system (e.g., an artificial pancreas system that can be operated without user intervention) or a semi-closed loop system (e.g., an insulin ring system that can be operated with little user intervention, such as to confirm changes in dosage). For example, the analyte level of diabetes can be monitored in a repeated automatic manner by the sensor control device 102, which can then communicate the monitored analyte level to the reader device 120, and can automatically determine the appropriate drug dose for controlling the analyte level of the diabetic patient and then deliver it to the body of the diabetic patient. Software instructions for controlling the pump and the amount of insulin delivered can be stored in the memory of the reader device 120 and executed by the processing circuit of the reader device. These instructions can also result in the calculation of the drug delivery amount and duration (e.g., a bolus infusion and / or a basic infusion curve) based on the analyte level measurements obtained directly or indirectly from the sensor control device 102. In some embodiments, the sensor control device 102 can determine the drug dose and communicate it to the reader device 120.

[0055] Example Implementation of a Sensor Control Device

[0056] Figure 3 1 is a block diagram depicting an example implementation of a sensor control device 102 having an analyte sensor 104 and sensor electronics 250 (including analyte monitoring circuitry) that may have the bulk of the processing power for rendering final result data suitable for display to a user. Figure 3, a single semiconductor chip 251, which may be a custom application specific integrated circuit (ASIC), is shown. Certain advanced functional units are shown in ASIC 251, including an analog front end (AFE) 252, a power management (or control) circuit 254, a processor 256, and a communication circuit 258 (which may be implemented as a transmitter, receiver, transceiver, passive circuit, or other device according to a communication protocol). In this embodiment, both the AFE 252 and the processor 256 are used as analyte monitoring circuits, but in other embodiments, either circuit may perform the analyte monitoring function. The processor 256 may include one or more processors, microprocessors, controllers, and / or microcontrollers, each of which may be a discrete chip or distributed among multiple different chips (or part of multiple different chips).

[0057] Memory 253 is also included in ASIC 251 and may be shared by various functional units present in ASIC 251, or may be distributed among two or more of them. Memory 253 may also be a separate chip. Memory 253 is non-temporary and may be volatile and / or non-volatile memory. In this embodiment, ASIC 251 is coupled to power supply 260, which may be a button battery or the like. AFE 252 interfaces with in vivo analyte sensor 104 and receives measurement data therefrom, and outputs the data in digital form to processor 256, which in some embodiments may be processed in any manner described elsewhere herein. Then, for example, the data may be provided to communication circuit 258 to be sent to reader device 120 (not shown) via antenna 261, for example, where the resident software application requires minimal further processing to display the data. Antenna 261 may be configured as required by the application and communication protocol. Antenna 261 may be, for example, a printed circuit board (PCB) trace antenna, a ceramic antenna, or a discrete metal antenna. The antenna 261 may be configured as a monopole antenna, a dipole antenna, an F-type antenna, a loop antenna, or the like.

[0058] Information may be transmitted from the sensor control device 102 to a second device (e.g., the reader device 120) at the initiative of the sensor control device 102 or the reader device 120. For example, when analyte information is available, the information may be communicated automatically and / or repeatedly (e.g., continuously) by the sensor control device 102, or according to a schedule (e.g., about every 1 minute, about every 5 minutes, about every 10 minutes, etc.), in which case the information may be stored or recorded in a memory of the sensor control device 102 for later communication. The information may be sent from the sensor control device 102 in response to a request being received by the second device. The request may be an automatic request, such as a request sent by the second device according to a schedule, or may be a request generated at the initiative of a user (e.g., an ad hoc request or a manual request). In some embodiments, a manual request for data is referred to as a "scan" of the sensor control device 102 or an "on-demand" data transmission from the device 102. In some embodiments, the second device may send a polling signal or data packet to the sensor control device 102, and the device 102 may treat each poll (or polls occurring at certain time intervals) as a request for data and, if data is available, may send such data to the second device. In many embodiments, the communication between the sensor control device 102 and the second device is secure (e.g., encrypted and / or between authenticated devices), but in some embodiments, data may be sent from the sensor control device 102 in an unsecured manner, such as broadcast to all listening devices within range.

[0059] Different types and / or forms and / or amounts of information may be sent as part of each communication, including, but not limited to, one or more of current sensor measurements (e.g., most recently acquired analyte level information corresponding in time to the time the reading was initiated), the rate of change of a metric measured over a predetermined time period, the rate of change of a metric (acceleration of the rate of change), or historical metric information corresponding to metric information acquired prior to a given reading and stored in a memory of the sensor control device 102.

[0060] Some or all of the real-time, historical, rate of change, rate of rate of change (e.g., acceleration or deceleration) information may be sent to the reader device 120 in a given communication or transmission. In certain embodiments, the type and / or form and / or amount of information sent to the reader device 120 may be pre-programmed and / or unchangeable (e.g., preset at the time of manufacture), or may not be pre-programmed and / or unchangeable so as to be selectable and / or changeable in the field one or more times (e.g., by activating a switch of the system, etc.). Thus, in certain embodiments, the reader device 120 may output a sensor-derived current (real-time) analyte value (e.g., in digital format), a current rate of change of the analyte (e.g., in the form of an analyte rate indicator such as an arrow pointing in a direction indicating the current rate), and analyte trend history data (e.g., in the form of a graphical trace) based on the sensor readings acquired and stored in the memory of the sensor control device 102. In addition, readings or measurements of the temperature on the skin or on the sensor may be collected by an optional temperature sensor 257. These readings or measurements may be transmitted (either individually or as aggregated measurements over time) from the sensor control device 102 to another device (e.g., the reader 120). However, instead of or in addition to actually displaying the temperature measurements to the user, the temperature readings or measurements may be used in conjunction with a software routine executed by the reader device 120 to correct or compensate the analyte measurements output to the user.

[0061] Implementation of system, apparatus and method for sensor fault detection

[0062] Example of characteristics of sensor failure in an analyte sensor

[0063] In vivo analyte sensors can be configured to sense one or more features in a living body. For example, one feature is an analyte level (e.g., glucose level), which is a measurement of the concentration of an analyte in a body fluid or gas. For electrochemical sensors, the presence of an analyte in a body fluid can cause the sensor to generate a response in the form of an electric current (ampere) or a charge (coulomb). For other types of sensors, the response can be in different forms, such as photon intensity (e.g., light). The responsiveness of an analyte sensor can be adversely affected by various factors, including but not limited to interference from vascular processes, biofouling, fiber encapsulation, neutrophils, or other immune responses at the sensor insertion site over time.

[0064] refer to Figure 4, graph 400 depicts example analyte measurements of an in vivo analyte sensor over time. Specifically, superscript graph 405 shows analyte level readings over time, while subscript graph 410 shows the rate of change over the same time period. According to graph 400, black rectangles 415 indicate analyte measurements during a time period when a sensor failure related to a leak occurred. Figure 4 As shown, during the time period indicated by rectangle 415, the analyte level reading and rate of change are both relatively high.

[0065] Example Implementation of Sensor Fault Detection Using Analyte Level Metrics and Thresholds

[0066] An example implementation of a sensor fault detection method based on analyte level metrics and thresholds will now be described. Before doing so, those skilled in the art will appreciate that any one or more steps of the exemplary methods described herein may be stored as software instructions in a non-transitory memory of a sensor control device, a reader device, a remote computer, or a trusted computer system, such as with respect to Figure 1 The stored instructions, when executed, may cause the processing circuitry of an associated device or computing system to perform any one or more steps of the example methods described herein. Those skilled in the art will also appreciate that in many embodiments, real-time sensor data, near real-time sensor data, or historical sensor data may be used to perform any one or more of the method steps described herein, including the calculation of analyte metrics and / or the determination of sensor failures.

[0067] Those skilled in the art will also understand that the instructions may be stored in a non-transitory memory on a single device (e.g., a sensor control device or a reader device), or alternatively, may be distributed across multiple discrete devices, which may be located in geographically dispersed locations (e.g., a cloud platform). Similarly, those skilled in the art will recognize that the representation of a computing device in the embodiments disclosed herein, such as Figure 1 Those shown are intended to cover both physical devices and virtual devices (or "virtual machines").

[0068] Figure 5 is a flow chart depicting an example implementation of a method 500 for sensor fault detection in an analyte sensor. In step 510, sensor data indicative of an analyte level (eg, glucose level) is received from an analyte sensor. Figure 1 As described, the analyte sensor may include at least a portion inserted into the user's body. At step 520, a rate of change from the most recent sensor data is calculated. In some embodiments, a first rate of change V1 at a particular time k may be calculated according to the following equation: V1(k) = [g(k) - g(k - Tl)] / Tl, where g is the analyte level and Tl is a unit of time.

[0069] According to some embodiments, at step 510, multiple rates of change of sensor data received from the analyte sensor can be calculated. As an example, if four rates of change are to be calculated at step 510, the second rate of change V2 can be calculated according to the following equation: V2(k) = [g(k) - g(k-T2)] / T2. Similarly, the rates of change of V3(k) and V4(k) can be calculated using the equations V3(k) = [g(k) - g(k-T3)] / T3 and V4(k) = [g(k) - g(k-T4)] / T4, respectively. Those skilled in the art will recognize that other numbers of rates of change (e.g., 5, 6, 7, etc.) can be calculated and are fully within the scope of the present disclosure.

[0070] exist Figure 5 In step 515, the rate of change calculated from step 510 is compared with a predetermined rate of change threshold. According to some embodiments, the predetermined rate of change threshold may be compared with the absolute value of the calculated rate of change. If the predetermined rate of change threshold is not exceeded, the method 500 returns to step 505.

[0071] Still reference Figure 5 In method 500, if any calculated rate of change exceeds a predetermined rate of change threshold, then in step 520, the sum of the analyte levels S(k) within a predetermined time window is calculated according to the following equation: S(k) = g(k) + g(k-Tl), where g is the analyte level and Tl is the time unit.

[0072] exist Figure 5 At step 525, the calculated sum of analyte levels is compared to a predetermined sum-based threshold. If the calculated sum of analyte levels does not exceed the predetermined sum-based threshold, method 500 returns to step 505. If the calculated sum of analyte levels exceeds the predetermined sum-based threshold, then at step 530, an indication of a sensor failure is generated. According to some embodiments, if an indication of a sensor failure is generated, a notification may be output to a user. For example, in some embodiments, the notification may be a visual and / or audible indication to a user that a sensor failure has been detected. In other embodiments, the notification may be a request displayed to a user via a graphical user interface, for example, to remove and / or replace an analyte sensor. In some embodiments, at step 535, the sensor is disabled.

[0073] Those skilled in the art will also appreciate that, in some embodiments, method 500 may be implemented by first calculating a sum of analyte levels and comparing the calculated sum to a predetermined sum-based threshold (steps 520, 525), and, thereafter, calculating a rate of change and comparing the rate of change to a predetermined rate of change threshold (steps 510, 515).

[0074] In other embodiments, the analyte level and the rate of change sum may be calculated simultaneously or in a nearly simultaneous manner and compared to respective thresholds. One skilled in the art will appreciate that an indication of sensor failure is generated at step 530 if both thresholds are exceeded.

[0075] According to another embodiment, the rate-based check in step 515 can be performed at time k1, while the sum-based check in step 525 can be performed at time k2. If both conditions are met, the time difference between k1 and k2 is calculated. If the calculated time difference is within a predetermined time difference threshold, an indication of a sensor failure is generated in step 530.

[0076] According to another embodiment of the method 500, the rate-based check at step 515 can be evaluated from any combination of all possible rates of change within the time window around the evaluation instance k1. For example, given points k1, k1-T1, and k1-T3, the absolute rate of change can be calculated based on the pairs (k1, k1-T1), (k1-T1, k1-T2), (k1-T2, k1-T3). In some embodiments, the absolute rate of change can also be calculated based on any non-adjacent combination (e.g., (k1, k1-T2)). Those skilled in the art will appreciate that the rates of change from other time instances can be compared with the predetermined rate of change threshold, and are fully within the scope of the present disclosure.

[0077] Still reference Figure 5 According to another embodiment of method 500, rather than comparing the highest absolute rate of change to a predetermined rate of change threshold, a central tendency (e.g., mean, median, or mode) of a plurality of rates of change may be compared to a predetermined rate of change threshold at step 515. In some embodiments, the central tendency value may be based on an absolute rate of change of the sensor data received from the analyte sensor.

[0078] For each embodiment of the method disclosed herein, the system and device capable of executing each of those embodiments are covered within the scope of the present disclosure. For example, embodiments of sensor control devices are disclosed, and these devices may have one or more analyte sensors, analyte monitoring circuits (e.g., analog circuits), memories (e.g., for storing instructions), power supplies, communication circuits, transmitters, receivers, clocks, counters, time, temperature sensors, processors (e.g., for executing instructions), which may perform any and all method steps, or help to perform any and all method steps. These sensor control device embodiments can be used and can be used to implement those steps performed by the sensor control device according to any method and all methods described herein. Similarly, embodiments of reader devices are disclosed, and these devices may have one or more memories (e.g., for storing instructions), power supplies, communication circuits, transmitters, receivers, clocks, counters, time, processors (e.g., for executing instructions), which may perform any and all method steps, or help to perform any and all method steps. These reader device embodiments can be used and can be used to implement those steps performed by the reader device according to any method and all methods described herein. Computer device and server embodiments are disclosed, and these devices may have one or more memories (e.g., for storing instructions), power supplies, communication circuits, transmitters, receivers, clocks, counters, times, and processors (e.g., for executing instructions), which may perform any and all method steps, or facilitate the performance of any and all method steps. These reader device embodiments may be used and can be used to implement those steps performed by the reader device according to any and all methods described herein.

[0079] The computer program instructions for operating according to the described subject matter can be written in any combination of one or more programming languages, including object-oriented programming languages, such as Java, JavaScript, Smalltalk, C++, C#, Transact-SQL, XML, PHP, etc. and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program instructions can be executed entirely on the user's computing device, partially on the user's computing device as a stand-alone software package, partially on the user's computing device, partially on a remote computing device, or entirely on a remote computing device or server. In the latter case, the remote computing device can be connected to the user's computing device through any type of network including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0080] It should be noted that all features, elements, components, functions and steps described with respect to any embodiment provided herein are intended to be freely combined and substituted with any other embodiment. If a feature, element, component, function or step is described only with respect to one embodiment, it should be understood that unless explicitly stated otherwise, the feature, element, component, function or step can be used with each other embodiment described herein. Therefore, this paragraph can be used as a prerequisite basis and written support for the introduction of claims at any time, which combines the features, elements, components, functions and steps in different embodiments together, or replaces the features, elements, components, functions and steps in the embodiment with those in another embodiment, even if the above description does not explicitly indicate that such a combination or substitution is possible in certain circumstances. It is explicitly acknowledged that the explicit description of each possible combination and substitution is very cumbersome, especially considering that the permissibility of each such combination and substitution will be easily recognized by a person of ordinary skill in the art.

[0081] To the extent that the embodiments disclosed herein include or operate in association with memory, storage, and / or computer-readable media, the memory, storage, and / or computer-readable media are non-transitory. Thus, to the extent that memory, storage, and / or computer-readable media are covered by one or more claims, the memory, storage, and / or computer-readable media are only non-transitory.

[0082] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0083] Although the embodiments are susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and described in detail herein. However, it should be understood that these embodiments are not limited to the specific forms disclosed, but rather, these embodiments will cover all modifications, equivalents, and alternative forms that fall within the spirit of the present disclosure. In addition, any features, functions, steps, or elements of the embodiments may be stated in or added to the claims, and negative limitations on the scope of the invention of the claims may be limited by features, functions, steps, or elements that are not within the scope of the claims.

Claims

1. An analyte monitoring system comprising: a sensor control device comprising an analyte sensor at least partially inserted into a user's body, a first processing circuit, and a first non-transitory memory, wherein the sensor control device is configured to collect sensor data indicative of an analyte level from the analyte sensor; and a reader device comprising a second processing circuit and a second non-transitory memory, Wherein at least one of the first non-transitory memory or the second non-transitory memory comprises instructions, which when executed cause at least one of the first processing circuit or the second processing circuit to: calculating a rate of change metric based on the collected sensor data; calculating a summed analyte level metric based on the collected sensor data; comparing the rate of change metric to a first threshold and comparing the sum of analyte levels metric to a second threshold; and generating an indication of a sensor fault in response to a determination that the rate of change metric exceeds the first threshold, the analyte level sum metric exceeds the second threshold, and a difference between a first time for calculating the rate of change metric and a second time for calculating the analyte level sum metric is less than a predetermined time difference threshold, wherein the rate of change metric is based on sensor data collected within a predetermined time window, and Wherein the summed analyte level metric comprises a sum of analyte level measurements within a second predetermined time window.

2. The analyte monitoring system of claim 1, wherein: The rate of change metric is a function of a plurality of rate of change values, wherein the analyte sensor is a glucose sensor.

3. The analyte monitoring system of claim 2, wherein: The rate of change metric is a central tendency of the plurality of rate of change values.

4. The analyte monitoring system of claim 1, wherein: The rate of change metric is based on two consecutive analyte data points of sensor data collected within the predetermined time window.

5. The analyte monitoring system of claim 1, wherein: The rate of change metric is based on two non-consecutive analyte data points of sensor data collected within the predetermined time window.

6. The analyte monitoring system of claim 1, wherein: The instructions to compare the rate-of-change metric to the first threshold include instructions to compare an absolute value of the rate-of-change metric to the first threshold.

7. The analyte monitoring system of claim 1, wherein: The instructions, when executed, further cause at least one of the first processing circuit or the second processing circuit to output a notification to a display of the reader device.

8. The analyte monitoring system of claim 7, wherein: The notification includes a visual or audible indication that a sensor failure has been detected.

9. The analyte monitoring system of claim 1, wherein: The instructions, when executed, further cause at least one of the first processing circuit or the second processing circuit to disable the analyte sensor.

10. A computer-implemented method for detecting a sensor failure, the method comprising: collecting sensor data indicative of an analyte level by a sensor control device, the sensor control device including an analyte sensor at least partially inserted into a user's body; calculating a rate of change metric based on the collected sensor data; calculating a summed analyte level metric based on the collected sensor data; comparing the rate of change metric to a first threshold and comparing the sum of analyte levels metric to a second threshold; as well as generating an indication of a sensor fault in response to a determination that the rate of change metric exceeds the first threshold, the analyte level sum metric exceeds the second threshold, and a difference between a first time for calculating the rate of change metric and a second time for calculating the analyte level sum metric is less than a predetermined time difference threshold, wherein the rate of change metric is based on sensor data collected within a predetermined time window, and Wherein the summed analyte level metric comprises a sum of analyte level measurements within a second predetermined time window.

11. The method according to claim 10, wherein: The rate of change measure is the central tendency of a plurality of rate of change values.

12. The method of claim 10, further comprising transmitting the collected sensor data to a reader device via wireless communication circuitry of the sensor control device.

13. The method of claim 12, further comprising outputting a notification to a display of the reader device. The method of claim 10 , further comprising disabling the analyte sensor.

Images