# US 2021/0330223 A1 · Sensor verification through forward voltage measurements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0330223 A1 - Document ID: US20210330223A1 - Status: Published application - Kind: A1 - Application number: 17/082,944 - Filed: 2020-10-28 - Published: 2021-10-28 - Earliest claimed: 2020-04-24 - Assignees: Covidien LP - Applicants: Covidien LP - Inventors: Christopher J. Meehan; Jacob D. Dove - Web page: https://patentgrep.com/patent/US20210330223A1 ## CPC - A61B 5/14552: {Details of sensors specially adapted therefor} - A61B 5/1455: using optical sensors, e.g. spectral photometrical oximeters - A61B 5/1495: Calibrating or testing of in-vivo probes - G01R 19/0084: {Measuring voltage only} - A61B 2560/0266: for monitoring or limiting apparatus function - A61B 2562/0238: Optical sensor arrangements for performing transmission measurements on body tissue - G01R 31/2635: {Testing light-emitting diodes, laser diodes or photodiodes} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A device for measuring oxygen saturation includes circuitry configured to determine a measured difference of forward voltage based on a first forward voltage at a first light emitting diode and a second forward voltage a second light emitting diode and determine that the first and second light emitting diodes are valid based on a calibrated difference of forward voltage and the measured difference of forward voltage. In response to the determination that the first and second light emitting diodes are valid, the circuitry is configured to determine an oxygen saturation level. ## Claims ### Claim 1 A device for measuring oxygen saturation, the device comprising: a memory configured to store a calibrated difference of forward voltage; and circuitry configured to: determine a measured difference of forward voltage based on a first forward voltage at a first light emitting diode and a second forward voltage at a second light emitting diode; determine that the first light emitting diode and the second light emitting diode are valid based on the calibrated difference of forward voltage and the measured difference of forward voltage; and in response to the determination that the first light emitting diode and the second light emitting diode are valid, determine an oxygen saturation level using the first light emitting diode and the second light emitting diode and output an indication of the oxygen saturation level. ### Claim 2 (depends on 1) The device of claim 1, wherein the circuitry is configured to: apply a first current at a magnitude of current with a positive polarity such that the first current flows from an anode of the first light emitting diode to a cathode of the first light emitting diode; measure, while the circuitry applies the first current, the first forward voltage across the anode of the first light emitting diode and the cathode of the first light emitting diode; apply a second current at the magnitude of current with a negative polarity such that the second current flows from an anode of the second light emitting diode to a cathode of the second light emitting diode; and measure, while the circuitry applies the second current, the second forward voltage across the anode of the second light emitting diode and the cathode of the second light emitting diode. ### Claim 3 (depends on 1) The device of claim 1, wherein, to determine that the first light emitting diode and the second light emitting diode are valid, the circuitry is configured to determine that a difference between the calibrated difference of forward voltage and the measured difference of forward voltage is less than a threshold value. ### Claim 4 (depends on 1) The device of claim 1, wherein an anode of the second light emitting diode is coupled to a cathode of the first light emitting diode and a cathode of the second light emitting diode is coupled to an anode of the first light emitting diode. ### Claim 5 (depends on 1) The device of claim 1, wherein the circuitry is configured to: apply a first current from a first terminal through a first cable to an anode of the first light emitting diode, from the anode of the first light emitting diode to a cathode of the first light emitting diode, and from the cathode of the first light emitting diode through a second cable to a second terminal; and measure the first forward voltage, wherein, to measure the first forward voltage, the circuitry is configured to measure a voltage across the first terminal and the second terminal while the circuitry applies the first current. ### Claim 6 (depends on 5) The device of claim 5, wherein the circuitry is configured to: apply a second current from the second terminal through the second cable to an anode of the second light emitting diode, from the anode of the second light emitting diode to a cathode of the second light emitting diode, and from the cathode of the second light emitting diode through the first cable to the first terminal; and measure the second forward voltage, wherein, to measure the second forward voltage, the circuitry is configured to measure a voltage across the first terminal and the second terminal while the circuitry applies the second current. ### Claim 7 (depends on 1) The device of claim 1, wherein, to determine the oxygen saturation level, the circuitry is configured to: determine a first intensity of a first received photonic signal corresponding to a first output photonic signal output using the first light emitting diode; determine a second intensity of a second received photonic signal corresponding to a second output photonic signal output using the second light emitting diode; and determine the oxygen saturation level based on the first intensity of the first received photonic signal and the second intensity of the second received photonic signal. ### Claim 8 (depends on 7) The device of claim 7, wherein, to determine the first intensity of the first received photonic signal, the circuitry is configured to drive the first light emitting diode to output the first output photonic signal towards a subject's tissue and receive, from a first detector, the first received photonic signal after the first output photonic signal transmits through the subject's tissue; and wherein, to determine the second intensity of the second received photonic signal, the circuitry is configured to drive the second light emitting diode to output the second output photonic signal towards the subject's tissue and receive, from a second detector, the second received photonic signal after the second output photonic signal transmits through the subject's tissue. ### Claim 9 (depends on 7) The device of claim 7, wherein the memory is further configured to store calibration information, and wherein, to determine the oxygen saturation level, the circuitry is configured to determine the oxygen saturation level based on the first intensity of the first received photonic signal and the second intensity of the second received photonic signal and further based on the calibration information. ### Claim 10 (depends on 9) The device of claim 9, wherein, to determine the oxygen saturation level, the circuitry is configured to: estimate a first wavelength for the first output photonic signal based on the calibration information; estimate a second wavelength for the second output photonic signal output based on the calibration information; and wherein, to determine the oxygen saturation level, the circuitry is configured to determine the oxygen saturation level based on the first intensity of the first received photonic signal and the second intensity of the second received photonic signal and further based on the first wavelength for the first output photonic signal and the second wavelength for the second output photonic signal. ### Claim 11 (depends on 9) The device of claim 9, wherein the circuitry is configured to decrypt the calibration information based on the measured difference of forward voltage. ### Claim 12 (depends on 1) The device of claim 1, wherein the first light emitting diode is configured to emit red light; and wherein the second light emitting diode is configured to emit infrared light. ### Claim 13 (depends on 1) The device of claim 1, wherein the circuitry is configured to estimate a temperature at one or more of the first light emitting diode or the second light emitting diode based on the measured difference of forward voltage. ### Claim 14 A method for measuring oxygen saturation, the method comprising: determining, by circuitry, a measured difference of forward voltage based on a first forward voltage at a first light emitting diode and a second forward voltage at a second light emitting diode; determining, by the circuitry, that the first light emitting diode and the second light emitting diode are valid based on a calibrated difference of forward voltage and the measured difference of forward voltage; and in response to determining that the first light emitting diode and the second light emitting diode are valid, determining, by the circuitry, an oxygen saturation level using the first light emitting diode and the second light emitting diode and outputting, by the circuitry, an indication of the oxygen saturation level. ### Claim 15 (depends on 14) The method of claim 14, further comprising: applying, by the circuitry, a first current at a magnitude of current with a positive polarity such that the first current flows from an anode of the first light emitting diode to a cathode of the first light emitting diode; measuring, by the circuitry, while applying the first current, the first forward voltage across the anode of the first light emitting diode and the cathode of the first light emitting diode; applying, by the circuitry, a second current at the magnitude of current with a negative polarity such that the second current flows from an anode of the second light emitting diode to a cathode of the second light emitting diode; and measuring, by the circuitry, while applying the second current, the second forward voltage across the anode of the second light emitting diode and the cathode of the second light emitting diode. ### Claim 16 (depends on 14) The method of claim 14, wherein determining that the first light emitting diode and the second light emitting diode are valid comprises determining that a difference between the calibrated difference of forward voltage and the measured difference of forward voltage is less than a threshold value. ### Claim 17 (depends on 14) The method of claim 14, wherein an anode of the second light emitting diode is coupled to a cathode of the first light emitting diode and a cathode of the second light emitting diode is coupled to an anode of the first light emitting diode. ### Claim 18 (depends on 14) The method of claim 14, applying, by the circuitry, a first current from a first terminal through a first cable to an anode of the first light emitting diode, from the anode of the first light emitting diode to a cathode of the first light emitting diode, and from the cathode of the first light emitting diode through a second cable to a second terminal; and measuring, by the circuitry, the first forward voltage, wherein measuring the first forward voltage comprises measuring a voltage across the first terminal and the second terminal while applying the first current. ### Claim 19 (depends on 18) The method of claim 18, applying, by the circuitry, a second current from the second terminal through the second cable to an anode of the second light emitting diode, from the anode of the second light emitting diode to a cathode of the second light emitting diode, and from the cathode of the second light emitting diode through the first cable to the first terminal; and measuring, by the circuitry, the second forward voltage, wherein measuring the second forward voltage comprises measuring a voltage across the first terminal and the second terminal while applying the second current. ### Claim 20 A system for measuring oxygen saturation, the system comprising: a sensor device comprising a first light emitting diode and a second light emitting diode; and an oximetry device comprising: a memory configured to store a calibrated difference of forward voltage; and circuitry configured to: determine a measured difference of forward voltage based on a first forward voltage at the first light emitting diode and a second forward voltage at the second light emitting diode; determine that the first light emitting diode and the second light emitting diode are valid based on the calibrated difference of forward voltage and the measured difference of forward voltage; and in response to the determination that the first light emitting diode and the second light emitting diode are valid, determine an oxygen saturation level using the first light emitting diode and the second light emitting diode and output an indication of the oxygen saturation level.