Detection of contamination at sensor contacts

• US 9,936,903 B2
• Filed: 04/13/2012
• Issued: 04/10/2018
• Est. Priority Date: 04/14/2011
• Status: Active Grant

• Current Assignee: Konamite Limited
• Original Assignee: WaveForm Technologies, Inc. (AgaMatrix Holdings LLC d/b/a WaveForm Diabetes)
• Inventors: Gofman, Igor, Wu, Mu
• Primary Examiner(s): Le, Toan
• Assistant Examiner(s): SUN, XIUQIN
• Application Number:
  US13/447,152
• Publication Number:
  US 20130018597A1
• Time in Patent Office: 2,188 Days
• Field of Search: 702 23
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors

Abstract

Embodiments herein provide detection of contamination at one or more contacts of a sensor system. The sensor system includes a sensor assembly and an electronics assembly communicatively coupled together by one or more contacts. The sensor assembly passes a sensor signal to the electronics assembly for further processing. The electronics assembly includes a detection contact for detecting contamination on or near one or more contacts of the sensor assembly and/or the electronics assembly. A switch selectively couples the detection contact to a bias voltage during a measurement mode and to a reference voltage during a detection mode, the reference voltage being different from the bias voltage. A method of contamination detection includes switching the electronics assembly between the measurement mode and the detection mode, and monitoring for a change in the output signal received by the electronics assembly.

Claims

1. An electronics assembly comprising:

a hermetic housing;

a sensor contact disposed on an exterior surface of the housing, and configured to receive a sensor signal from a sensor assembly when the sensor assembly is coupled to the electronics assembly, the sensor signal being representative of a level of an analyte in a body;

a processor coupled to the sensor contact and configured to receive the sensor signal;

an open detection contact disposed on the exterior surface of the housing that is not couplable to any contact on the sensor assembly and is configured to detect a leakage current between the sensor contact and the open detection contact due to contamination at or near the sensor contact; and

a switch coupled to the detection contact, controlled by the processor, and configured to couple the detection contact to a bias voltage during a measurement mode and to couple the detection contact to a reference voltage during a detection mode, the reference voltage being different from the bias voltage,

wherein the processor is configured to periodically switch from the measurement mode to the detection mode and measure a first value of the sensor signal during the measurement mode and a second value of the sensor signal during the detection mode to detect a leakage current of the sensor signal, wherein if the difference between the first value and the second value is greater than a threshold amount, the processor identifies that there is a leakage current present.

2. The electronics assembly of claim 1, wherein the processor is configured to compare the first value to the second value to determine whether the leakage current is present.

3. The electronics assembly of claim 2, wherein the electronics assembly is further configured to take an action based on the comparison of the first value to the second value, the action including at least one of:

activating an alarm, generating an error code, transmitting the error code to an external device, logging an error, stopping collection of data from the sensor assembly, preventing the sensor data from being used in data processing, and/or taking the leakage current into account in data processing.

4. The electronics assembly of claim 2, wherein the processor is configured to take an action if a result of the comparison between the first value and the second value is above a threshold.

5. The electronics assembly of claim 1, wherein the processor is configured to transmit the first and second values to a monitoring unit, the monitoring unit configured to determine whether the leakage current is present based on the first and second values.

6. The electronics assembly of claim 1, further comprising:

a transimpedance amplifier configured to receive the sensor signal at an input terminal and to pass an amplified sensor signal to the processor, the amplified sensor signal having a voltage dependent on a current of the sensor signal at the input terminal;

wherein the transimpedance amplifier is biased with the bias voltage.

7. The electronics assembly of claim 1, further comprising a battery, wherein the detection contact is configured to be coupled with a battery charger to charge the battery during a charging mode of the electronics assembly.

8. The electronics assembly of claim 7, wherein the switch comprises a first switch and the electronics assembly further comprising:

a second switch configured to couple the detection contact to the battery during the charging mode and to couple the detection contact to the first switch during the measurement mode and the detection mode.

9. The electronics assembly of claim 8, further comprising an enable contact configured to receive a control signal from the battery charger to place the electronics assembly in the charging mode.

10. The electronics assembly of claim 1, further comprising a common return contact coupled to a ground potential and configured to be coupled with the sensor assembly.

11. The electronics assembly of claim 10, wherein the reference voltage is equal to the ground potential.

12. The electronics assembly of claim 10, wherein the sensor contact, detection contact, and the common return contact are disposed in a sealed portion between the electronics assembly and the sensor assembly when the electronics assembly is coupled with the sensor assembly.

13. The electronics assembly of claim 1, wherein the detection contact comprises a guard ring that surrounds the sensor contact.

14. The electronics assembly of claim 1, wherein the sensor assembly includes a continuous glucose monitor configured to produce the sensor signal.

15. An analyte sensor system, comprising:

a sensor assembly including;

a first sensor contact;

a first ground contact; and

an analyte sensor coupled to the first sensor contact and the first ground contact, the analyte sensor configured to produce a sensor signal at the first sensor contact that is representative of a level of an analyte in a body; and

an electronics assembly that reversibly couples to the sensor assembly, the electronics assembly including;

a hermetic housing

a second sensor contact disposed on an exterior surface of the housing and configured to be coupled with the first sensor contact to receive the sensor signal;

a second ground contact disposed on the exterior surface of the housing and coupled to the first ground contact and to a ground potential;

a processor coupled to the second sensor contact and configured to receive the sensor signal;

an open detection contact disposed on the exterior surface of the housing that is not couplable to any contact of the sensor assembly and is configured to detect a leakage current between the sensor contact and the open detection contact due to contamination at or near the sensor contact; and

a switch coupled to the detection contact and controlled by the processor, the switch configured to couple the detection contact to a bias voltage during a measurement mode and to couple the detection contact to a reference voltage during a detection mode, the reference voltage being different from the bias voltage, wherein the processor is configured to periodically switch from the measurement mode to the detection mode and measure a first value of the sensor signal during the measurement mode and a second value of the sensor signal during the detection mode to detect a leakage current of the sensor signal, wherein if the difference between the first value and the second value is greater than a threshold amount, the processor identifies that there is a leakage current present.

16. The system of claim 15, wherein the processor is configured to compare the first value to the second value to determine whether the leakage current is present, and to take an action if a result of the comparison is above a threshold.

17. The system of claim 15, wherein the electronics assembly further comprises a transimpedance amplifier configured to receive the sensor signal at an input terminal and to pass an amplified sensor signal to the processor, wherein the transimpedance amplifier is biased with the bias voltage.

18. The system of claim 15, wherein the electronics assembly further comprises a battery, and wherein the detection contact is configured to be coupled with a battery charger to charge the battery during a charging mode of the electronics assembly.

19. The system of claim 18, wherein the electronics assembly further comprises an enable contact configured to receive a control signal from the battery charger to place the electronics assembly in the charging mode.

20. The system of claim 18, wherein the reference voltage is equal to the ground potential.

21. The system of claim 15, wherein the first and second sensor contacts, first and second ground contacts, and the detection contact are disposed in a sealed portion between the electronics assembly housing and the sensor assembly when the electronics assembly and the sensor assembly are coupled.

22. The system of claim 15, wherein the detection contact comprises a guard ring that surrounds the second sensor contact.

23. The system of claim 15, wherein the analyte sensor includes a continuous glucose monitor.