Use of electrochemical impedance spectroscopy (EIS) in gross failure analysis
Electrochemical Impedance Spectroscopy (EIS) is used in conjunction with continuous glucose monitors and continuous glucose monitoring (CGM) to enable in-vivo sensor calibration, gross (sensor) failure analysis, and intelligent sensor diagnostics and fault detection. An equivalent circuit model is defined, and circuit elements are used to characterize sensor behavior.
1. A system comprising:
a glucose sensor device for determining a concentration of glucose in a body of a user, the sensor device comprising:
a first electrochemical peroxide-based glucose sensor;
a first electrochemical oxygen-based sensor;
a second electrochemical oxygen-based sensor;
a processor; and
a memory storing instructions thereon which, when executed by the processor, cause the sensor device to:
receive a peroxide-based output signal from the first electrochemical peroxide-based glucose sensor, the peroxide-based output signal being indicative of a level of glucose in the body of the user;
receive a first oxygen-based output signal from the first electrochemical oxygen-based sensor and a second oxygen-based output signal from the second electrochemical oxygen-based sensor;
calculate a single oxygen-based signal based on the first and second oxygen-based output signals, wherein the single oxygen-based signal is indicative of the level of glucose in the body of the user;
fuse the peroxide-based output signal and the single oxygen-based signal to calculate a single, fused sensor glucose value for a blood glucose level in the body of the user; and
calculate, based on a membrane resistance of each sensor of the sensor device, a first weight for the peroxide-based output signal and a second weight for the single oxygen-based signal,
wherein the fused sensor glucose value is based on fusing the peroxide-based output signal and the single oxygen-based signal using the first weight and the second weight, respectively.
2. The system of claim 1 , wherein the sensor device is configured to be either implanted or subcutaneously disposed in the body of the user.
3. The system of claim 1 , further comprising a transmitter configured to transmit the fused sensor glucose value to an external device.
4. The system of claim 1 , wherein the peroxide-based output signal further indicates a level of oxygen consumed via a chemistry stack of the electrochemical peroxide-based glucose sensor.
5. The system of claim 1 , further comprising an insulin pump.
6. The system of claim 5 , wherein the system is a closed-loop system.
7. The system of claim 1 , wherein the first electrochemical oxygen-based sensor includes Glucose Oxidase (GOx) as a catalyst and is operated at a negative potential.
8. The system of claim 7 , wherein the second electrochemical oxygen-based sensor does not include GOx and is operated at a negative potential.
9. The system of claim 8 , wherein the instructions, when executed by the processor, further cause the system to calculate the single oxygen-based signal by computing a difference between the first oxygen-based output signal and the second oxygen-based output signal.
10. The system of claim 1 , further including a second electrochemical peroxide-based glucose sensor, wherein the first and second peroxide-based glucose sensors are redundant glucose sensors.
11. A computer-implemented method for determining a level of glucose in a body of a user, the computer implemented method comprising:
receiving a peroxide-based output signal from a first electrochemical peroxide-based glucose sensor of a glucose sensor device, the peroxide-based output signal being indicative of a level of glucose in the body of the user;
receiving a first oxygen-based output signal from a first electrochemical oxygen-based sensor of the glucose sensor device and a second oxygen-based output signal from a second electrochemical oxygen-based sensor of the glucose sensor device;
calculating a single oxygen-based signal based on the first and second oxygen-based output signals, wherein the single oxygen-based signal is indicative of the level of glucose in the body of the user;
fusing the peroxide-based output signal and the single oxygen-based signal to calculate a single, fused sensor glucose value for a blood glucose level in the body of the user; and
calculating, based on a membrane resistance of each sensor of the sensor device, a first weight for the peroxide-based output signal and a second weight for the single oxygen-based signal,
wherein the fused sensor glucose value is based on fusing the peroxide-based output signal and the single oxygen-based signal using the first weight and the second weight, respectively.
12. The computer-implemented method of claim 11 , wherein the glucose sensor device is configured to be either implanted or subcutaneously disposed in the body of the user.
13. The computer-implemented method of claim 12 , further comprising calculating the level of glucose in the body of the user by computing a difference between the output signal of the first electrochemical oxygen-based sensor and the output signal of the second electrochemical oxygen-based sensor.
14. The computer-implemented method of claim 11 , wherein the first electrochemical peroxide-based glucose sensor is carried on a first flex, and the first electrochemical oxygen-based sensor is carried on a second flex.
15. The computer-implemented method of claim 12 , further comprising transmitting the fused sensor glucose value by a transmitter to an external device.
16. The computer-implemented method of claim 12 , wherein the peroxide-based output signal further indicates a level of oxygen consumed via a chemistry stack of the electrochemical peroxide-based glucose sensor.
17. The computer-implemented method of claim 12 , wherein the first electrochemical oxygen-based sensor includes Glucose Oxidase (GOx) as a catalyst and is operated at a negative potential.
18. A non-transitory machine-readable medium comprising instructions which, when executed by one or more processors, cause operations comprising:
receiving a peroxide-based output signal from a first electrochemical peroxide-based glucose sensor of a glucose sensor device, the peroxide-based output signal being indicative of a level of glucose in a body of a user;
receiving a first oxygen-based output signal from a first electrochemical oxygen-based sensor of the glucose sensor device and a second oxygen-based output signal from a second electrochemical oxygen-based sensor of the glucose sensor device;
calculating a single oxygen-based signal based on the first and second oxygen-based output signals, wherein the single oxygen-based signal is indicative of the level of glucose in the body of the user;
fusing the peroxide-based output signal and the single oxygen-based signal to calculate a single, fused sensor glucose value for a blood glucose level in the body of the user; and
calculating, based on a membrane resistance of each sensor of the sensor device, a first weight for the peroxide-based output signal and a second weight for the single oxygen-based signal,
wherein the fused sensor glucose value is based on fusing the peroxide-based output signal and the single oxygen-based signal using the first weight and the second weight, respectively.