System and method for health monitoring using a non-invasive, multi-band biosensor
View Patent ↗A biosensor includes a PPG circuit that emits light directed at skin tissue at a plurality of wavelengths. A first and second spectral response of light reflected from the tissue is obtained around a first wavelength and a second wavelength. Using absorption coefficients for substances at the plurality of wavelengths, concentration levels of a plurality of substances may then be determined from the spectral responses. The biosensor may thus be used to determine concentrations of a plurality of substances in arterial blood flow using the spectral response.
1. A biosensor, comprising:
a PPG circuit configured to:
emit light having at least a first wavelength and a second wavelength directed at skin tissue of a patient;
generate a first spectral response using light around the first wavelength reflected from the skin tissue of the patient;
generate a second spectral response using light around the second wavelength reflected from the skin tissue of the patient;
a processing circuit configured to:
isolate a systolic point and a diastolic point in the first spectral response and obtain a value L λ1 using a ratio of the systolic point and the diastolic point in the first spectral response;
isolate a systolic point and a diastolic point in the second spectral response and obtain a value L λ2 using a ratio of the systolic point and diastolic point in the second spectral response;
obtain a value R λ1, λ2 from a ratio of the value L λ1 and the value L λ2 , wherein the value R λ1, λ2 is an indicator of one or more liver enzymes;
obtain a blood alcohol level using a calibration table and the value R λ1, λ2 ; and
transmit the blood alcohol level for display.
2. The biosensor of claim 1 , wherein the first spectral response generated for light detected around the first wavelength is responsive to a liver enzyme cytochrome oxidase (P450) released in response to alcohol in pulsating arterial blood flow.
3. The biosensor of claim 2 , wherein the value R λ1, λ2 obtained from the ratio of the value L λ1 and the value L λ2 correlates to an indicator of the P450 liver enzyme.
4. The biosensor of claim 3 , wherein the processing circuit is further configured to output the indicator of the P450 liver enzyme.
5. The biosensor of claim 4 , wherein the first frequency has a high absorption coefficient for the P450 liver enzyme.
6. The biosensor of claim 5 , wherein the first frequency is at approximately 468 nm.
7. The biosensor of claim 5 , wherein the second frequency has a low absorption coefficient for the P450 liver enzyme.
8. The biosensor of claim 5 , wherein the PPG circuit is configured to generate the first spectral response for light detected at the wavelength of 468 nm and for wavelengths in a range of 1 nm to 50 nm around 468 nm.
9. The biosensor of claim 8 , wherein the calibration table includes a range of R λ1, λ2 values and correlated blood alcohol levels, wherein the calibration table is generated using blood alcohol level measurements obtained from a sample population during a same measurement period as the range of R λ1, λ2 values is obtained by the biosensor for the sample population.
10. A biosensor, comprising:
a PPG circuit configured to:
generate at least a first spectral response for light reflected around a first wavelength from skin tissue of the patient;
generate at least a second spectral response for light reflected around a second wavelength from the skin tissue of the patient;
a processing circuit configured to:
obtain a value L λ1 using the first spectral response, wherein the value L λ1 isolates the first spectral response due to pulsating arterial blood flow;
obtain a value L λ2 using the second spectral response, wherein the value L λ2 isolates the second spectral response due to pulsating arterial blood flow;
obtain a value R λ1, λ2 from a ratio of the value L λ1 and the value L λ2 ;
obtain a liver enzyme indicator based on the value R λ1, λ2 that indicates a liver enzyme concentration level in the pulsating arterial blood flow; and
obtain a blood alcohol level using a calibration table and the value R λ1, λ2 .
11. The biosensor of claim 10 , further comprising:
a wireless transceiver configured to transmit the blood alcohol level to a remote device.
12. The biosensor of claim 10 , wherein the first spectral response generated for light detected around the first wavelength is responsive to a liver enzyme, wherein a concentration level of the liver enzyme increases in the pulsating arterial blood flow in response to alcohol intake by the patient.
13. The biosensor of claim 12 , wherein the liver enzyme includes cytochrome oxidase (P450).
14. The biosensor of claim 13 , wherein the first frequency has a high absorption coefficient for P450 and the second frequency has a low absorption coefficient for P450.
15. The biosensor of claim 14 , wherein the first frequency is approximately 468 nm and the second frequency is approximately 940 nm.
16. The biosensor of claim 13 , wherein the PPG circuit is configured to generate the first spectral response for light detected at the wavelength of 468 nm and for wavelengths in a range of 1 nm to 50 nm around 468 nm.
17. The biosensor of claim 16 , wherein the calibration table includes a range of R λ1, λ2 values and correlated blood alcohol levels, wherein the calibration table is generated using blood alcohol level measurements obtained from a sample population during a same measurement period as the range of R λ1, λ2 values is obtained by the biosensor of the sample population.
18. A method for measuring blood alcohol levels, comprising:
generating at least a first spectral response for light reflected around a first wavelength from skin tissue of the patient;
generating at least a second spectral response for light detected around a second wavelength reflected from the skin tissue of the patient;
obtaining a value L λ1 using the first spectral response, wherein the value L λ1 isolates the first spectral response due to pulsating arterial blood flow;
obtaining a value L λ2 using the second spectral response, wherein the value L λ2 isolates the second spectral response due to pulsating arterial blood flow;
obtaining a value R λ1, λ2 from a ratio of the value L λ1 and the value L λ2 , wherein the value R λ1, λ2 is the indicator of a concentration level of a liver enzyme of the patient;
obtaining a blood alcohol concentration level of the patient from a calibration table and the value R λ1, λ2 , wherein the calibration table includes a range of R λ1, λ2 values and correlated blood alcohol concentration levels; and
transmitting the blood alcohol concentration level of the patient for display.
19. The method of claim 18 , wherein the first spectral response for light reflected around a first wavelength from skin tissue of the patient is responsive to a liver enzyme cytochrome oxidase (P450) released in response to alcohol in pulsating arterial blood flow.
20. The biosensor of claim 19 , wherein the calibration table includes a range of R λ1, λ2 values and correlated blood alcohol levels, wherein the calibration table is generated using blood alcohol level measurements obtained from a sample population during a same measurement period as the range of R λ1, λ2 values is obtained by the biosensor of the sample population.