System and method for detecting a health condition using an optical sensor

Abstract

A biosensor includes an optical sensor circuit that emits light directed at skin tissue of a patient at a plurality of wavelengths. A first and second spectral response of light reflected from the tissue is obtained around a first wavelength in a UV range and a second wavelength in an IR range. A measurement of a substance in blood flow is then determined from the spectral responses. A risk of a health condition is obtained using the measurement. The health condition may include one or more of hyperglycemia, diabetes or hypoglycemia.

What is claimed: 
     
         1 . A biosensor for detecting a sepsis condition, comprising:
 a photoplethysmography (PPG) circuit configured to:
 obtain a first PPG signal from light reflected from or transmitted through skin tissue of a patient, wherein the light includes a first wavelength in an ultraviolet (UV) range; 
 obtain a second PPG signal from light reflected from or transmitted through the skin tissue of the patient, wherein the light includes a second wavelength; and 
   a processing circuit configured to determine a risk of sepsis using the first PPG signal and the second PPG signal.   
     
     
         2 . The biosensor of  claim 1 , wherein the processing circuit is configured to determine a risk of sepsis using the first PPG signal and the second PPG signal by:
 determining a concentration level of nitric oxide (NO) in blood flow using the first PPG signal and the second PPG signal; and   determining the risk of sepsis using the concentration level of NO in blood flow.   
     
     
         3 . The biosensor of  claim 2 , wherein the concentration level of NO in blood flow includes one or more of: a concentration level of NO in a gaseous form or a concentration level of NO attached to hemoglobin compounds. 
     
     
         4 . The biosensor of  claim 3 , wherein the processing circuit is configured to determine the risk of sepsis using the concentration level of NO in blood flow by:
 comparing the concentration level of NO to one or more predetermined thresholds; and   determining the risk of sepsis based on the comparison of the concentration level of NO to the one or more predetermined thresholds.   
     
     
         5 . The biosensor of  claim 4 , wherein the one or more predetermined thresholds includes a threshold of a concentration level of NO indicating an overproduction of NO that induces excessive vascular relaxation or a profound hypotension. 
     
     
         6 . The biosensor of  claim 4 , wherein the one or more predetermined thresholds includes a threshold of a concentration level of NO that exceeds a hemoglobin saturation level. 
     
     
         7 . The biosensor of  claim 4 , wherein the one or more predetermined thresholds includes a first threshold of a concentration level of NO indicating a risk of sepsis, wherein the first threshold of the concentration level of NO exceeds a baseline level of a normal NO measurement by at least 10%. 
     
     
         8 . The biosensor of  claim 4 , wherein the one or more predetermined thresholds includes a second threshold of a concentration level of NO indicating a high risk of sepsis, wherein the second threshold of the concentration level of NO exceeds a baseline level of a normal NO measurement by at least 30%. 
     
     
         9 . A biosensor for detecting a sepsis condition, comprising:
 one or more processing circuits and a memory device that stores instructions which when executed by the one or more processing circuits, causes the one or more processing circuits to:
 process a first PPG signal from light reflected from or transmitted through skin tissue of a patient around a first wavelength to determine a first AC component of the first PPG signal; 
 process a second PPG signal from light reflected from or transmitted through the skin tissue of the patient around a second wavelength to determine a second AC component of the second PPG signal; and 
 determine a risk of sepsis using the first AC component and the second AC component. 
   
     
     
         10 . The biosensor of  claim 9 , wherein the one or more processing circuits are further configured to:
 determine a ratio value using the first AC component and the second AC component; and   determine a risk of sepsis using the ratio value.   
     
     
         11 . The biosensor of  claim 10 , wherein the ratio value is an R value determined using the first AC component and the second AC component. 
     
     
         12 . The biosensor of  claim 9 , wherein the one or more processing circuits are configured to determine the first AC component by averaging the first AC component of the first PPG signal over at least one respiratory cycle; and
 wherein the processing circuit is configured to determine the second AC component by averaging the second AC component of the second PPG signal over at least one respiratory cycle.   
     
     
         13 . The biosensor of  claim 9 , wherein the first wavelength has a high absorption coefficient for NO in blood flow and is in a range of approximately 380 nm to 410 nm. 
     
     
         14 . The biosensor of  claim 9 , further comprising:
 a temperature sensor configured to measure a skin temperature; and   wherein the one or more processing circuits are further configured to:
 determine a risk of sepsis using the first AC component, the second AC component and the skin temperature. 
   
     
     
         15 . The biosensor of  claim 9 , wherein the biosensor is implemented on a disposable patch. 
     
     
         16 . The biosensor of  claim 9 , wherein the disposable patch comprises at least one of:
 a visible indicator of the risk of sepsis; or   an audible indicator for providing an audible indication of the risk of sepsis.   
     
     
         17 . A method for detecting a sepsis condition, comprising:
 obtaining a first PPG signal from light reflected from or transmitted through skin tissue of a patient at a first wavelength;   obtaining a second PPG signal from light reflected from or transmitted through the skin tissue of the patient at a second wavelength; and   determining a risk of sepsis using the first PPG signal and the second PPG signal.   
     
     
         18 . The method of  claim 17 , further comprising:
 determining a concentration level of nitric oxide (NO) in blood flow using the first PPG signal and the second PPG signal; and   determining the risk of sepsis using the concentration level of NO in blood flow.   
     
     
         19 . The method of  claim 18 , wherein the concentration level of NO in blood flow includes one or more of: a concentration level of NO in a gaseous form or a concentration level of NO attached to hemoglobin compounds. 
     
     
         20 . The method of  claim 19 , further comprising:
 comparing the concentration level of NO to one or more predetermined thresholds; and   determining the risk of sepsis based on the comparison of the concentration level of NO to the one or more predetermined thresholds.