Sensor systems, devices, and methods for continuous glucose monitoring

Abstract

Electrochemical impedance spectroscopy (EIS) may be used in conjunction with continuous glucose monitoring (CGM) to enable identification of valid and reliable sensor data, as well implementation of Smart Calibration algorithms.

1 - 21 . (canceled) 
     
     
         22 . A continuous glucose monitoring system, comprising:
 a glucose sensor configured for subcutaneous placement in a user and having a sensor electrode configured to be exposed to body fluid of the user for determining a blood glucose value; and   a monitor in communication with the glucose sensor and configured to receive the blood glucose value from the glucose sensor, the monitor including a power source, a processor, and a memory storing instructions which, when executed by the processor, cause the processor to:
 determine an electrode current of the sensor electrode based on a voltage applied to the sensor electrode by the power source of the monitor; 
 perform an electrochemical impedance spectroscopy procedure for the sensor electrode to obtain an impedance value of the sensor electrode; 
 calculate a calibrated sensor glucose value associated with the electrode current; 
 calculate an amount of insulin for delivery to the user based on the calibrated sensor glucose value; and 
 communicate the calculated amount of insulin to an external device for facilitating delivery of the calculated amount of insulin to the user. 
   
     
     
         23 . The continuous glucose monitoring system according to  claim 22 , wherein the instructions, when executed by the processor, further cause the processor to determine an expected calibration error based on the impedance value of the sensor electrode. 
     
     
         24 . The continuous glucose monitoring system according to  claim 23 , wherein the instructions, when executed by the processor, further cause the processor to provide a variable calibration error threshold based on the expected calibration error. 
     
     
         25 . The continuous glucose monitoring system according to  claim 24 , wherein the instructions, when executed by the processor, further cause the processor to update a calibration factor with an accepted blood glucose value based on the variable calibration error threshold. 
     
     
         26 . The continuous glucose monitoring system according to  claim 25 , wherein the calibrated sensor glucose value is calculated based on the updated calibration factor and the accepted blood glucose value. 
     
     
         27 . The continuous glucose monitoring system according to  claim 25 , wherein the instructions, when executed by the processor, further cause the processor to:
 calculate an expected calibration factor value based on an age of the glucose sensor; and   weight the updated calibration factor value using the expected calibration factor value, wherein the calibrated sensor glucose value associated with the electrode current is calculated based on the weighted updated calibration factor and the accepted blood glucose value.   
     
     
         28 . The continuous glucose monitoring system according to  claim 27 , wherein the instructions, when executed by the processor, further cause the processor to increase the expected calibration factor over time. 
     
     
         29 . The continuous glucose monitoring system according to  claim 22 , wherein the external device includes at least one of an insulin infusion pump or a mobile computing device. 
     
     
         30 . A continuous glucose monitoring system, comprising:
 a glucose sensor configured for subcutaneous placement in a user and having a sensor electrode configured to be exposed to body fluid of the user for determining a blood glucose value; and   a monitor in communication with the glucose sensor and configured to receive the blood glucose value from the glucose sensor, the monitor including a power source, a processor, and a memory storing instructions which, when executed by the processor, cause the processor to:
 determine an electrode current of the sensor electrode based on a voltage applied to the sensor electrode by the power source of the monitor; 
 determine an expected calibration error based on an impedance value of the sensor electrode; 
 determine a variable calibration error threshold based on the expected calibration error; 
 update a calibration factor based on the variable calibration error threshold; 
 calculate a calibrated sensor glucose value associated with the electrode current based on the updated calibration factor; and 
 calculate an amount of insulin for delivery to the user based on the calibrated sensor glucose value. 
   
     
     
         31 . The continuous glucose monitoring system according to  claim 30 , wherein the instructions, when executed by the processor, further cause the processor to communicate the calculated amount of insulin to an external device for facilitating delivery of the calculated amount of insulin to the user. 
     
     
         32 . The continuous glucose monitoring system according to  claim 30 , wherein the instructions, when executed by the processor, further cause the processor to update the calibration factor with an accepted blood glucose value. 
     
     
         33 . The continuous glucose monitoring system according to  claim 32 , wherein the calibrated sensor glucose value is calculated based on the updated calibration factor and the accepted blood glucose value. 
     
     
         34 . The continuous glucose monitoring system according to  claim 30 , wherein the instructions, when executed by the processor, further cause the processor to perform an electrochemical impedance spectroscopy procedure for the sensor electrode to obtain the impedance value of the sensor electrode. 
     
     
         35 . The continuous glucose monitoring system according to  claim 30 , wherein the instructions, when executed by the processor, further cause the processor to communicate the calculated amount of insulin to an external device for facilitating delivery of the calculated amount of insulin to the user. 
     
     
         36 . The continuous glucose monitoring system according to  claim 30 , wherein the external device includes at least one of an insulin infusion pump or a mobile computing device. 
     
     
         37 . A continuous glucose monitoring system, comprising:
 a glucose sensor configured for subcutaneous placement in a user and having a sensor electrode configured to be exposed to body fluid of the user for determining a blood glucose value; and   a monitor in communication with the glucose sensor and configured to receive the blood glucose value from the glucose sensor, the monitor including a power source, a processor, and a memory storing instructions which, when executed by the processor, cause the processor to:
 determine an electrode current of the sensor electrode based on a voltage applied to the sensor electrode by the power source of the monitor; 
 determine a calibration error threshold based on an expected calibration error; 
 update a calibration factor based on the calibration error threshold; 
 calculate a calibrated sensor glucose value based on the updated calibration factor; 
 calculate an amount of insulin for delivery to the user based on the calibrated sensor glucose value; and 
 communicate the calculated amount of insulin to an external device for facilitating delivery of the calculated amount of insulin to the user. 
   
     
     
         38 . The continuous glucose monitoring system according to  claim 37 , wherein the instructions, when executed by the processor, further cause the processor to perform an electrochemical impedance spectroscopy procedure for the sensor electrode to obtain an impedance value of the sensor electrode. 
     
     
         39 . The continuous glucose monitoring system according to  claim 38 , wherein the expected calibration error is determined based on the impedance value of the sensor electrode. 
     
     
         40 . The continuous glucose monitoring system according to  claim 37 , wherein the calibration error threshold is a variable calibration error threshold. 
     
     
         41 . The continuous glucose monitoring system according to  claim 37 , wherein the external device includes at least one of an insulin infusion pump or a mobile computing device.