# US 10,945,630 B2 · Use of Electrochemical Impedance Spectroscopy (EIS) in gross failure analysis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,945,630 B2 - Document ID: US10945630B2 - Status: Granted - Kind: B2 - Application number: 14/466,160 - Filed: 2014-08-22 - Published: 2015-06-18 - Granted: 2021-03-16 - Earliest claimed: 2013-12-16 - Assignees: Medtronic MiniMed, Inc. - Applicants: Medtronic Minimed, Inc. - Inventors: Andrea Varsavsky; Fei Yu; Ning Yang - Web page: https://patentgrep.com/patent/US10945630B2 ## CPC - A61B 5/0537: Measuring body composition by impedance, e.g. tissue hydration or fat content - A61B 5/0538: invasively, e.g. using a catheter - A61B 5/14532: {for measuring glucose, e.g. by tissue impedance measurement} - A61B 5/1468: using chemical or electrochemical methods, e.g. by polarographic means - A61B 5/1473: invasive, e.g. introduced into the body by a catheter - A61B 5/14865: {invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors} - A61B 5/1495: Calibrating or testing of in-vivo probes - A61B 5/7221: {Determining signal validity, reliability or quality (preventing, reducing or removing noise induced by motion artefacts A61B5/7207; noise originating from a therapeutic or surgical apparatus A61B5/7217)} - A61B 5/7246: {using correlation, e.g. template matching or determination of similarity} - A61M 5/1582: {Multi-lumen needles} - G01N 27/026: {Dielectric impedance spectroscopy (electrochemical impedance spectroscopy for measuring corrosion G01N17/02)} - A61B 5/6849: {in combination with a needle set} - A61M 5/14244: {adapted to be carried by the patient, e.g. portable on the body} - A61M 5/14276: {specially adapted for implantation} - A61M 2005/1726: {the body parameters being measured at, or proximate to, the infusion site} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract 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. ## Claims ### Claim 1 A method of performing diagnostics on a subcutaneous or implanted glucose sensor having at least one working electrode, comprising: defining a vector containing values associated with one or more electrochemical impedance spectroscopy (EIS)-based parameters and values associated with one or more non-EIS-based parameters; defining a combined threshold value for a combination of said EIS-based parameters and said non-EIS-based parameters; performing, by a microprocessor, a first EIS procedure to generate a first set of data for said values associated with the one or more EIS-based parameters; after a calculated time interval, performing, by said microprocessor, a second EIS procedure to generate a second set of data for said values associated with the one or more EIS-based parameters; updating, by said microprocessor, the vector with said first and second sets of data; and monitoring, by said microprocessor, vector values to determine whether the sensor has lost sensitivity based on a combined vector value of said combination of EIS-based and non-EIS-based parameters crossing said combined threshold value, wherein sensor glucose values are blinded to a user of the sensor by the microprocessor based on the determination that the sensor has lost sensitivity. ### Claim 2 (depends on 1) The method of claim 1, wherein said one or more EIS-based parameters include double layer capacitance (Cdl). ### Claim 3 (depends on 1) The method of claim 1, wherein said one or more non-EIS-based parameters include a period of time during which Isig is low. ### Claim 4 (depends on 1) The method of claim 1, further including periodically updating the vector values for each of said non-EIS-based parameters. ### Claim 5 (depends on 4) The method of claim 4, wherein said determination of sensitivity loss is made based on comparison of one of the vector values to a corresponding threshold value. ### Claim 6 (depends on 4) The method of claim 4, wherein the sensor is determined to have lost sensitivity when a plurality of the vector values have crossed their corresponding threshold values. ### Claim 7 (depends on 6) The method of claim 6, wherein said plurality of vector values include values for at least one EIS-based parameter and at least one non-EIS-based parameter. ### Claim 8 (depends on 1) The method of claim 1, wherein each of said threshold values is an absolute threshold value. ### Claim 9 (depends on 1) The method of claim 1, wherein each of said threshold values is a relative threshold value. ### Claim 10 (depends on 1) The method of claim 1, further including applying a weighting factor to each of the vector values to generate weighted vector values, and determining sensitivity loss based on said weighted vector values. ### Claim 11 (depends on 10) The method of claim 10, wherein said weighting factor is different for each of the EIS-based parameters and for each of the non-EIS-based parameters. ### Claim 12 (depends on 11) The method of claim 11, wherein, for each said EIS-based parameter and each said non-EIS-based parameter, a respective weighting factor is calculated based on each parameter's said respective threshold value. ### Claim 13 (depends on 1) The method of claim 1, wherein said combined threshold value is an absolute threshold value. ### Claim 14 (depends on 1) The method of claim 1, wherein said combined threshold value is a relative threshold value. ### Claim 15 (depends on 1) The method of claim 1, wherein said one or more EIS-based parameters include membrane resistance (Rmem). ### Claim 16 (depends on 1) The method of claim 1, wherein said one or more EIS-based parameters include membrane capacitance (Cmem). ### Claim 17 (depends on 1) The method of claim 1, wherein said one or more non-EIS-based parameters include variability in sensor current (Isig). ### Claim 18 (depends on 1) The method of claim 1, wherein said one or more non-EIS-based parameters include rate of change of Isig. ### Claim 19 A method of performing diagnostics on a subcutaneous or implanted glucose sensor having at least one working electrode, comprising: defining a vector containing values associated with one or more electrochemical impedance spectroscopy (EIS)-based parameters and values associated with one or more non-EIS-based parameters; defining a combined threshold value for a combination of said EIS-based parameters and said non-EIS-based parameters; performing, by a microprocessor, a first EIS procedure to generate a first set of data for said values associated with the one or more EIS-based parameters; after a calculated time interval, performing, by said microprocessor, a second EIS procedure to generate a second set of data for said values associated with the one or more EIS-based parameters; updating, by said microprocessor, the vector with said first and second sets of data; monitoring, by said microprocessor, vector values to determine whether the sensor has lost sensitivity based on a combined vector value of said combination of EIS-based and non-EIS-based parameters crossing said combined threshold value; and terminating said glucose sensor by the microprocessor based on the determination that the sensor has lost sensitivity.