# US 2019/0167170 A1 · Methods and systems for improving the reliability of orthogonally redundant sensors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0167170 A1 - Document ID: US20190167170A1 - Status: Published application - Kind: A1 - Application number: 16/266,385 - Filed: 2019-02-04 - Published: 2019-06-06 - Earliest claimed: 2013-12-16 - Assignees: Medtronic MiniMed, Inc. - Applicants: Medtronic Minimed, Inc. - Inventors: Andrea Varsavsky; Xiaolong Li; Mike C. Liu; Yuxiang Zhong; Ning Yang - Web page: https://patentgrep.com/patent/US20190167170A1 ## CPC - A61B 5/14532: {for measuring glucose, e.g. by tissue impedance measurement} - A61B 5/0004: {characterised by the type of physiological signal transmitted} - 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)} - A61B 5/1455: using optical sensors, e.g. spectral photometrical oximeters - A61B 5/14556: {by fluorescence (A61B5/14555 takes precedence)} - A61B 5/1459: invasive, e.g. introduced into the body by a catheter - 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 5/1495: Calibrating or testing of in-vivo probes - A61B 5/4839: {combined with drug delivery} - 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 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals} - A61M 5/142: Pressure infusion, e.g. using pumps - A61M 5/14244: {adapted to be carried by the patient, e.g. portable on the body} - A61M 5/1723: {using feedback of body parameters, e.g. blood sugar or pressure} - C12Q 1/006: {for glucose} - G01N 21/00: Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light (G01N3/00 - G01N19/00 take precedence) - G01N 21/59: Transmissivity (G01N21/25 takes precedence) - G01N 21/84: Systems specially adapted for particular applications - G01N 27/27: Association of two or more measuring systems or cells, each measuring a different parameter, where the measurement results may be either used independently, the systems or cells being physically associated, or combined to produce a value for a further parameter - G01N 27/3274: {Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration (coding of calibration information G01N33/48771)} - G01N 27/4163: {checking the operation of, or calibrating, the measuring apparatus (G01N27/3274, G01N27/4175 and G01N33/0006 take precedence)} - G01N 33/49: Blood {(chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80)} - G01N 33/66: involving blood sugars, e.g. galactose - A61B 2560/0223: of calibration, e.g. protocols for calibrating sensors - A61B 2560/0238: Means for recording calibration data - A61B 2562/06: Arrangements of multiple sensors of different types - A61M 2005/1726: {the body parameters being measured at, or proximate to, the infusion site} - A61M 2205/3306: Optical measuring means - A61M 2205/3584: using modem, internet or Bluetooth® - A61M 2205/3592: using telemetric means, e.g. radio or optical transmission - A61M 2205/50: with microprocessors or computers - A61M 2205/505: Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches - A61M 2205/52: with memories providing a history of measured variating parameters of apparatus or patient - A61M 2230/005: Parameter used as control input for the apparatus - A61M 2230/201: Glucose concentration - G01N 2201/127: Calibration; base line adjustment; drift compensation - 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)} - C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES - 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 Methods and systems for sensor calibration and sensor glucose (SG) fusion are used advantageously to improve the accuracy and reliability of orthogonally redundant glucose sensor devices, which may include optical and electrochemical glucose sensors. Calibration for both sensors may be achieved via fixed-offset and/or dynamic regression methodologies, depending, e.g., on sensor stability and Isig-Ratio pair correlation. For SG fusion, respective integrity checks may be performed for SG values from the optical and electrochemical sensors, and the SG values calibrated if the integrity checks are passed. Integrity checks may include checking for sensitivity loss, noise, and drift. If the integrity checks are failed, in-line sensor mapping between the electrochemical and optical sensors may be performed prior to calibration. The electrochemical and optical SG values may be weighted (as a function of the respective sensor's overall reliability index (RI)) and the weighted SGs combined to obtain a single, fused SG value. ## Claims ### Claim 1 A continuous glucose monitoring system comprising: an orthogonally redundant glucose sensor device comprising an optical glucose sensor and an electrochemical glucose sensor; and a transmitter operatively coupled to said electrochemical and optical glucose sensors and having a housing, wherein the transmitter includes sensor electronics in said housing, said sensor electronics including at least one physical microprocessor that is configured to: perform a status check on each of the electrochemical glucose sensor and the optical glucose sensor; calculate a first reliability index for an output signal of the electrochemical sensor based on a reliability index for each of sensor dip, sensor noise, sensor sensitivity loss, sensor cal ratio, and sensor accuracy for the electrochemical glucose sensor; calculate a second reliability index for an output signal of the optical sensor based on said status check for the optical sensor; calibrate the output signal of the electrochemical sensor to obtain an electrochemical sensor glucose value (echem SG); calibrate the output signal of the optical sensor to obtain an optical sensor glucose value (optical SG); calculate a first weight based on said first reliability index and calculate a weighted echem SG based on said first weight; calculate a second weight based on said second reliability index and calculate a weighted optical SG based on said second weight; and calculate a single, fused sensor glucose value based on said weighted echem SG and weighted optical SG. ### Claim 2 (depends on 1) The system of claim 1, wherein said status check on the optical glucose sensor is based on a value of said output signal of the optical glucose sensor. ### Claim 3 (depends on 1) The system of claim 1, wherein said status check on the optical glucose sensor is based on at least one of a previous cal ratio, a previous sensor accuracy, a sensitivity loss flag, and a dip flag for the optical glucose sensor. ### Claim 4 (depends on 3) The system of claim 3, wherein said cal ratio for the optical glucose sensor is defined as a meter glucose value divided by the optical glucose sensor's output signal. ### Claim 5 (depends on 1) The system of claim 1, wherein said first weight is a linear function of said first reliability index, said second weight is a linear function of said second reliability index, or both. ### Claim 6 (depends on 1) The system of claim 1, wherein said first weight is a non-linear function of said first reliability index, said second weight is a non-linear function of said second reliability index, or both. ### Claim 7 (depends on 1) The system of claim 1, wherein said single, fused sensor glucose value is calculated by adding said weighted echem SG to said weighted optical SG. ### Claim 8 (depends on 1) The system of claim 1, wherein the optical glucose sensor includes an assay fluorophore and a reference fluorophore, wherein the assay fluorophore generates an assay fluorescence signal and the reference fluorophore generates a reference fluorescence signal, and wherein said output signal of the optical glucose sensor is a ratio of the assay fluorescence signal to the reference fluorescence signal. ### Claim 9 (depends on 1) The system of claim 1, wherein the transmitter is configured to be worn on a body of a user. ### Claim 10 (depends on 1) The system of claim 1, further including a handheld monitor. ### Claim 11 (depends on 10) The system of claim 10, wherein the handheld monitor includes an integrated blood glucose meter. ### Claim 12 (depends on 11) The system of claim 11, wherein the transmitter wirelessly transmits said single, fused sensor glucose value to the hand-held monitor. ### Claim 13 (depends on 1) The system of claim 1, further including an insulin pump, wherein the transmitter wirelessly transmits said single, fused sensor glucose value to the insulin pump. ### Claim 14 (depends on 13) The system of claim 13, wherein said glucose monitoring system is a closed-loop system. ### Claim 15 (depends on 1) The system of claim 1, wherein each of the electrochemical and optical sensors has a distal portion and a proximal portion, and wherein respective distal portions of the optical sensor and the electrochemical sensor are configured to be co-located within a user's body. ### Claim 16 A continuous glucose monitoring system comprising: an orthogonally redundant glucose sensor device comprising an optical glucose sensor and an electrochemical glucose sensor; and a transmitter operatively coupled to said electrochemical and optical glucose sensors and having a housing, wherein the transmitter includes sensor electronics in said housing, said sensor electronics including at least one physical microprocessor that is configured to: perform a status check on each of the electrochemical glucose sensor and the optical glucose sensor; calculate a first reliability index for an output signal of the electrochemical sensor based on said status check for the electrochemical sensor; calculate a second reliability index for an output signal of the optical sensor based on a reliability index for each of sensor dip, sensor noise, sensor sensitivity loss, sensor cal ratio, and sensor accuracy for the optical glucose sensor; calibrate the output signal of the electrochemical sensor to obtain an electrochemical sensor glucose value (echem SG); calibrate the output signal of the optical sensor to obtain an optical sensor glucose value (optical SG); calculate a first weight based on said first reliability index and calculate a weighted echem SG based on said first weight; calculate a second weight based on said second reliability index and calculate a weighted optical SG based on said second weight; and calculate a single, fused sensor glucose value based on said weighted echem SG and weighted optical SG. ### Claim 17 (depends on 16) The system of claim 16, wherein said status check on the electrochemical glucose sensor is based on a value of said output signal of the electrochemical glucose sensor. ### Claim 18 (depends on 16) The system of claim 16, wherein said first weight is a linear function of said first reliability index, said second weight is a linear function of said second reliability index, or both. ### Claim 19 (depends on 16) The system of claim 16, wherein said first weight is a non-linear function of said first reliability index, said second weight is a non-linear function of said second reliability index, or both. ### Claim 20 (depends on 16) The system of claim 16, wherein said single, fused sensor glucose value is calculated by adding said weighted echem SG to said weighted optical SG. ### Claim 21 (depends on 16) The system of claim 16, wherein the optical glucose sensor includes an assay fluorophore and a reference fluorophore, wherein the assay fluorophore generates an assay fluorescence signal and the reference fluorophore generates a reference fluorescence signal, and wherein said output signal of the optical glucose sensor is a ratio of the assay fluorescence signal to the reference fluorescence signal. ### Claim 22 (depends on 16) The system of claim 16, wherein the transmitter is configured to be worn on a body of a user. ### Claim 23 (depends on 16) The system of claim 16, further including a handheld monitor. ### Claim 24 (depends on 23) The system of claim 23, wherein the handheld monitor includes an integrated blood glucose meter. ### Claim 25 (depends on 24) The system of claim 24, wherein the transmitter wirelessly transmits said single, fused sensor glucose value to the hand-held monitor. ### Claim 26 (depends on 16) The system of claim 16, further including an insulin pump, wherein the transmitter wirelessly transmits said single, fused sensor glucose value to the insulin pump. ### Claim 27 (depends on 26) The system of claim 26, wherein said glucose monitoring system is a closed-loop system. ### Claim 28 (depends on 16) The system of claim 16, wherein each of the electrochemical and optical sensors has a distal portion and a proximal portion, and wherein respective distal portions of the optical sensor and the electrochemical sensor are configured to be co-located within a user's body.