Advanced analyte sensor calibration and error detection

• US 10,624,568 B2
• Filed: 08/13/2019
• Issued: 04/21/2020
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Bohm, Sebastian, Rong, Daiting, Simpson, Peter C.
• Primary Examiner(s): Previl, Daniel
• Application Number:
  US16/539,945
• Publication Number:
  US 20190357817A1
• Time in Patent Office: 252 Days
• Field of Search: 340604, 340612, 34063611-63615, 3406916, 3405391, 3405721-5729
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 2560/04 Constructional details of apparatus
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14503 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors A61B5/1459, A61B5/1464, A61B5/1473, A61B5/1482, A61B5/14865 take precedence
• CPC Class Codes: A61B 5/1451 for interstitial fluid
• CPC Class Codes: A61B 5/14517 for sweat
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/14735 comprising an immobilised reagent
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150992 Blood sampling from a fluid line external to a patient, such as a catheter line, combined with an infusion line; blood sampling from indwelling needle sets, e.g. sealable ports, luer couplings, valves tubing connectors and couplings A61M39/00
• CPC Class Codes: A61B 5/155 : Devices specially adapted for continuous or multiple sampling, e.g. at predetermined intervals devices loaded with multiple lancets simultaneously A61B5/15146
• CPC Class Codes: A61B 5/157 : Devices characterised by integrated means for measuring characteristics of blood
• CPC Class Codes: A61B 5/412 : Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/4839 : combined with drug delivery
• CPC Class Codes: A61B 5/6848 : Needles
• CPC Class Codes: A61B 5/6849 : in combination with a needle set
• CPC Class Codes: A61B 5/6866 : Extracorporeal blood circuits, e.g. dialysis circuits
• CPC Class Codes: A61B 5/7257 : using Fourier transforms
• CPC Class Codes: A61B 5/7267 : involving training the classification device
• CPC Class Codes: A61B 5/7275 : Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/743 : Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: A61M 2005/14296 : Pharmacokinetic models
• CPC Class Codes: A61M 2230/201 : Glucose concentration
• CPC Class Codes: A61M 5/14 : Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
• CPC Class Codes: A61M 5/16804 : Flow controllers
• CPC Class Codes: A61M 5/1723 : using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: C12Q 1/001 : Enzyme electrodes
• CPC Class Codes: C12Q 1/006 : for glucose
• CPC Class Codes: G01D 18/00 : Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01N 27/026 : Dielectric impedance spectroscopy electrochemical impedance spectroscopy for measuring corrosion G01N17/02
• CPC Class Codes: G01N 27/3274 : Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: G01N 33/49 : Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80
• CPC Class Codes: G16H 10/40 : for data related to laboratory analysis, e.g. patient specimen analysis
• CPC Class Codes: G16H 20/17 : delivered via infusion or injection
• CPC Class Codes: G16H 40/40 : for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: G16H 40/63 : for local operation
• CPC Class Codes: H05K 999/00 : dummy group
• CPC Class Codes: H05K 999/99 : dummy group
• CPC Class Codes: Y02A 90/10 : Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

Systems and methods for processing sensor data and self-calibration are provided. In some embodiments, systems and methods are provided which are capable of calibrating a continuous analyte sensor based on an initial sensitivity, and then continuously performing self-calibration without using, or with reduced use of, reference measurements. In certain embodiments, a sensitivity of the analyte sensor is determined by applying an estimative algorithm that is a function of certain parameters. Also described herein are systems and methods for determining a property of an analyte sensor using a stimulus signal. The sensor property can be used to compensate sensor data for sensitivity drift, or determine another property associated with the sensor, such as temperature, sensor membrane damage, moisture ingress in sensor electronics, and scaling factors.

Claims

1. A method of making an analyte concentration measuring system for use by a host during a sensor session with a transcutaneous electrochemical analyte sensor, the method comprising:

applying a membrane located over at least a portion of an electrode of the transcutaneous electrochemical analyte sensor, wherein the transcutaneous electrochemical analyte sensor is configured to generate a signal indicative of an analyte concentration, wherein the transcutaneous electrochemical analyte sensor comprises;

an ex vivo portion configured to remain outside of a body of the host during the sensor session; and

an in vivo portion configured to be inserted into the body of the host and remain, during the sensor session, in the body of the host;

obtaining data associated with a plurality of sensor characteristics of the transcutaneous electrochemical analyte sensor prior to the sensor session, wherein obtaining the data comprises at least;

measuring a first sensor characteristic, wherein the first sensor characteristic is associated with an in vitro glucose sensitivity corresponding to a sample set of transcutaneous electrochemical analyte sensors;

measuring a second sensor characteristic, wherein the second sensor characteristic is associated with a thickness of the membrane of the transcutaneous electrochemical analyte sensor; and

assigning one or more calibration codes to the transcutaneous electrochemical analyte sensor, wherein the one or more calibration codes is based at least in part on the measured first sensor characteristic associated with the in vitro glucose sensitivity and the measured second sensor characteristic associated with the thickness of the membrane.

2. The method of claim 1, wherein the one or more calibration codes are part of a calibration encoded label.

3. The method of claim 1, wherein the transcutaneous electrochemical analyte sensor is formed as a wire.

4. The method of claim 1, further comprising measuring a length of time the transcutaneous electrochemical analyte sensor was dipped in a particular coating solution, and wherein the one or more calibration codes are further based at least in part on the measured dipping length of time.

5. The method of claim 1, wherein the transcutaneous electrochemical analyte sensor is planar.

6. The method of claim 1, wherein the sample set of transcutaneous electrochemical sensors comprises the transcutaneous electrochemical analyte sensor.

7. The method of claim 1, wherein the sample set of transcutaneous electrochemical sensors and the transcutaneous electrochemical analyte sensor are from a same sensor lot.

8. A method, comprising:

determining a sample sensitivity associated with a sample set, wherein the sample set comprises a plurality of transcutaneous electrochemical analyte sensors, wherein the sample set is part of a sensor lot, wherein each transcutaneous electrochemical analyte sensor of the plurality of transcutaneous electrochemical analyte sensors of the sample set, comprises;

an ex vivo portion configured to remain outside of a body of a host during a sensor session; and

an in vivo portion configured to be inserted into the body of the host and remain, during the sensor session, in the body of the host;

determining an adjustment factor for a first transcutaneous electrochemical analyte sensor, wherein the first transcutaneous electrochemical analyte sensor is from the sensor lot, wherein the adjustment factor is associated with a parameter that affects sensor sensitivity;

determining a sensor sensitivity for the first transcutaneous electrochemical analyte sensor based at least in part on the sample sensitivity and the adjustment factor; and

calibrating sensor data, generated by the first transcutaneous electrochemical analyte sensor, based at least in part on the determined sensor sensitivity.

9. The method of claim 8, wherein the parameter is associated with a membrane thickness of the first transcutaneous electrochemical analyte sensor.

10. The method of claim 8, wherein the first transcutaneous electrochemical analyte sensor is planar.

11. A method, comprising:

determining a sample sensitivity associated with a sample set, wherein the sample set comprises a plurality of transcutaneous electrochemical analyte sensors, wherein the sample set is part of a sensor lot, wherein each transcutaneous electrochemical analyte sensor of the plurality of transcutaneous electrochemical analyte sensors of the sample set, comprises;

an ex vivo portion configured to remain outside of a body of the host during a sensor session; and

an in vivo portion configured to be inserted into the body of the host and remain, during the sensor session, in the body of the host;

determining a first adjustment factor for a first transcutaneous electrochemical analyte sensor in the sensor lot, wherein the first adjustment factor is associated with a first parameter that affects sensor sensitivity;

determining a second adjustment factor for the first transcutaneous electrochemical analyte sensor in the sensor lot, wherein the second adjustment factor is associated with a second parameter that affects sensor sensitivity, wherein the second parameter is different from the first parameter;

determining a sensor sensitivity for the first transcutaneous electrochemical analyte sensor based at least in part on the sample sensitivity, the first adjustment factor, and the second adjustment factor; and

calibrating sensor data, generated by the first transcutaneous electrochemical analyte sensor, based at least in part on the determined sensor sensitivity.

12. The method of claim 11, wherein the first parameter and the second parameter are associated with at least one property of a membrane associated with the first transcutaneous electrochemical analyte sensor.

13. The method of claim 11, wherein the first parameter is associated with a membrane thickness of the first transcutaneous electrochemical analyte sensor.

14. The method of claim 13, wherein the second parameter is associated with an enzyme-related property of the membrane.

15. The method of claim 11, wherein the first transcutaneous electrochemical analyte sensor is planar.

16. An analyte sensor system comprising:

a transcutaneous electrochemical analyte sensor from a sensor lot, wherein the transcutaneous electrochemical analyte sensor comprises;

a first portion configured to be disposed ex vivo during a sensor session; and

a second portion configured to be disposed in vivo during the sensor session, wherein the second portion comprises;

an electrode configured to generate a signal associated with an analyte concentration; and

a membrane disposed over at least a portion of the electrode; and

sensor electronics operably connectable to the first portion of the transcutaneous electrochemical analyte sensor, wherein the sensor electronics comprise information associated with sensor calibration, wherein the information associated with sensor calibration is determined based at least in part on;

a sensor sensitivity associated with a sample set, wherein the sample set comprises a plurality of transcutaneous electrochemical analyte sensors, wherein the plurality of transcutaneous electrochemical analyte sensors are from the sensor lot; and

an adjustment factor for the transcutaneous electrochemical analyte sensor, wherein the adjustment factor is associated with a parameter that affects sensor sensitivity.

17. The analyte sensor system of claim 16, wherein the adjustment factor is associated with a thickness of the membrane of the transcutaneous electrochemical analyte sensor.

18. The analyte sensor system of claim 16, further comprising a receiver.

19. The analyte sensor system of claim 18, wherein the receiver is configured to:

receive, from the sensor electronics, the information associated with sensor calibration;

receive, from the sensor electronics, sensor data indicative of an analyte concentration; and

determine an estimated glucose value based at least in part on the sensor data and the information associated with sensor calibration.

20. The analyte sensor system of claim 16, wherein the information associated with sensor calibration is a calibration code.

21. The analyte sensor system of claim 16, wherein the transcutaneous electrochemical analyte sensor is planar.