System for noninvasive determination of alcohol in tissue

Abstract

An apparatus and method for non-invasive determination of attributes of human tissue by quantitative infrared spectroscopy to clinically relevant levels of precision and accuracy. The system includes subsystems optimized to contend with the complexities of the tissue spectrum, high signal- to-noise ratio and photometric accuracy requirements, tissue sampling errors, calibration maintenance problems, and calibration transfer problems. The subsystems include an illumination/modulation subsystem, a tissue sampling subsystem, a calibration maintenance subsystem, an FTIR spectrometer subsystem, a data acquisition subsystem, and a computing subsystem.

We claim: 
     
         1 . An apparatus for determining an analyte property of a sample, comprising:
 a. An illumination subsystem comprising a semiconductor light source;   b. A sampling subsystem, mounted with the illumination subsystem such that light from the illumination subsystem is directed to a sample by the sampling subsystem;   c. A data acquisition subsystem, mounted with the sampling subsystem such that light from the sample is communicated from the sampling subsystem to the data acquisition subsystem;   d. A computing subsystem, mounted with the data acquisition subsystem such that the computing subsystem can determine the analyte property from information from the data acquisition subsystem.   
     
     
         2 . An apparatus as in  claim 1 , wherein the sampling subsystem comprises an interface to in vivo tissue. 
     
     
         3 . An apparatus as in  claim 2 , wherein the interface to in vivo tissue comprises an interface to tissue of a human hand. 
     
     
         4 . An apparatus as in  claim 3 , wherein the interface to tissue of a human hand comprises an interface to tissue on the top of one or more fingers between the first and second knuckles thereof. 
     
     
         5 . An apparatus as in  claim 1 , wherein the illumination subsystem comprises a plurality of semiconductor light sources. 
     
     
         6 . An apparatus as in  claim 5 , wherein the output of the plurality of semiconductor light sources is optically combined before communication to the sample. 
     
     
         7 . An apparatus as in  claim 5 , wherein the output of the plurality of semiconductor light sources is homogenized spatially, angularly, or both, before communication to the spectrometer. 
     
     
         8 . An apparatus as in  claim 5 , wherein each semiconductor light source is characterized by a center wavelength different from the center wavelengths of other of the plurality of semiconductor light sources. 
     
     
         9 . An apparatus as in  claim 8 , wherein each semiconductor light source is modulated at a modulation frequency different than the modulation frequency of other of the plurality of semiconductor light sources. 
     
     
         10 . An apparatus as in  claim 9 , wherein the modulation is according to one or more of Fourier, Hadamard, Fishers, z transform, sinusoidal, square, and triangular wave modulation. 
     
     
         11 . An apparatus as in  claim 9 , wherein the correspondence of semiconductor light source to modulation frequency is random. 
     
     
         12 . An apparatus as in  claim 9 , wherein the modulation is performed by one or more of controlling drive voltage of the semiconductor light source, controlling drive current of the semiconductor light source, controlling drive power of the semiconductor light source, controlling a mechanical mask mounted with the illumination subsystem, controlling an optical mask mounted with the illumination subsystem, controlling a filter wheel mounted with the illumination subsystem, controlling a chopper wheel mounted with the illumination subsystem, controlling an electrically controlled optical component mounted with the illumination subsystem, controlling a liquid crystal device mounted with the illumination subsystem, controlling a digital mirror device mounted with the illumination subsystem, controlling an acouto-optic tunable filter mounted with the illumination subsystem. 
     
     
         13 . An apparatus as in  claim 1 , wherein the semiconductor light source comprises at least one of VCSEL, diode laser, quantum cascade laser, quantum dot laser, LED, HCSEL, organic LED. 
     
     
         14 . An apparatus as in  claim 1 , wherein at least one of the drive current, drive voltage, drive power, and temperature of the semiconductor light source is stabilized. 
     
     
         15 . An apparatus as in  claim 1 , wherein at least one of the emission wavelength and emission profile of the semiconductor light source is tuned by controlling at least one of drive voltage, drive current, drive power, or temperature of the semiconductor light source. 
     
     
         16 . An apparatus as in  claim 7 , wherein the light is homogenized by at least one of a light pipe and a diffuser. 
     
     
         17 . An apparatus as in  claim 1 , wherein the analyte property is at least one of: concentration of one or more analytes, presence of one or more analytes, direction of change of concentration of one or more analytes, rate of change of concentration of one or more analytes, and presence of one or more interferents that tend to cause errors in the measurement of one or more other analyte properties. 
     
     
         18 . An apparatus as in  claim 2 , wherein the analyte property is at least one of: concentration of one or more analytes, presence of one or more analytes, direction of change of concentration of one or more analytes, rate of change of concentration of one or more analytes, presence of one or more interferents that tend to cause errors in the measurement of one or more other analyte properties, and a biometric property of the tissue. 
     
     
         19 . A method of determining an analyte property in a human, comprising
 a. Providing an apparatus as in  claim 2 ;   b. Using the apparatus to determine optical properties of tissue of the human;   c. Using the computing subsystem to determine the analyte property.   
     
     
         20 . A method as in  claim 19 , wherein the computing subsystem uses information from previous interactions with the apparatus in combination with information from the present interaction with the apparatus in the determination of the analyte property. 
     
     
         21 . A method as in  claim 19 , wherein the computing subsystem does not use information from previous interactions with the apparatus in combination with information from the present interaction with the apparatus in the determination of the analyte property. 
     
     
         22 . A method as in  claim 19 , wherein the analyte property is at least one of: concentration of one or more analytes, presence of one or more analytes, direction of change of concentration of one or more analytes, rate of change of concentration of one or more analytes, presence of one or more interferents that tend to cause errors in the measurement of one or more other analyte properties, and a biometric property of the tissue. 
     
     
         23 . A method as in  claim 22 , wherein the analyte property is at least two of:
 concentration of one or more analytes, presence of one or more analytes, direction of change of concentration of one or more analytes, rate of change of concentration of one or more analytes, presence of one or more interferents that tend to cause errors in the measurement of one or more other analyte properties, and a biometric property of the tissue.   
     
     
         24 . A method as in  claim 22 , wherein the analyte is at least one of: alcohol, alcohol byproducts, alcohol markers, and alcohol adducts. 
     
     
         25 . A method as in  claim 19 , wherein the analyte property comprises both determination of an analyte concentration and determination of a biometric property. 
     
     
         26 . (canceled) 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . An apparatus as in  claim 1 , wherein the sampling subsystem communicates light to the sample at a plurality of distinct regions of the sample. 
     
     
         31 . An apparatus as in  claim 1 , wherein the sampling subsystem collects light from a plurality of distinct regions of the sample.