Non-invasive system and method for measuring an analyte in the body

Abstract

A system for determining an analyte concentration in a fluid sample (e.g., glucose) comprises a light source, a detector, and a central processing unit. The detector is adapted to receive spectral information corresponding to light returned from the fluid sample being analyzed and to convert the received spectral information into an electrical signal indicative of the received spectral information. The central processing unit is adapted to compare the electrical signal to an algorithm built upon correlation with the analyte in body fluid. The algorithm is adapted to convert the received spectral information into the analyte concentration in body fluid. Spectral information is delivered from the central processing unit to the light source and used to vary the intensity and timing of the light to improve the accuracy of conversion into analyte concentration.

1 . A system for determining the concentration of an analyte in a fluid sample, the system comprising:
 a light source delivering light within a predetermined wavelength range;   a detector adapted to receive spectral information corresponding to light returned from said fluid sample and to convert the received spectral information into an electrical signal indicative of the received spectral information; and   a central processing unit adapted to compare the electrical signal to an algorithm built upon correlation with the analyte in the body fluid, the algorithm adapted to convert the received spectral information into the concentration of said analyte in said fluid sample, the central processing unit controlling the light source and varying the intensity and timing of the delivery of said light within said predetermined wavelength range to improve the accuracy of conversion of the received spectral information into concentration of said analyte in said fluid sample.   
     
     
         2 . The system of  claim 1 , wherein said light source is a series of beams of monochromatic light that scan across the predetermined wavelength range. 
     
     
         3 . The system of  claim 2 , further comprising a reference detector adapted to receive a portion of said series of beams of monochromatic light and to convert the received light into a reference electrical signal. 
     
     
         4 .- 12 . (canceled) 
     
     
         13 . The system of  claim 1 , wherein said light source delivers to said sample predetermined wavelengths of light at predetermined intensities and said spectral information returned from said sample is processed to provide spectral information at wavelengths where said analyte is more readily distinguished from interfering substances. 
     
     
         14 . The system of  claim 1 , wherein said light source contains information that is used to correct for the effect on the light spectra of the sample, light delivery and collection systems, and detector. 
     
     
         15 . The system of  claim 1 , wherein said light source contains information that corrects for changes in the analyte-related spectrum by the sample, light delivery and collection methods, and detector distortions. 
     
     
         16 . The system of  claim 1 , wherein said light source contains concentration-related spectra that correct for non-linear responses of the analyte. 
     
     
         17 . A method for determining the concentration of an analyte in a fluid sample, the method comprising the acts of:
 delivering light within a predetermined wavelength range from a light source;   receiving spectral information corresponding to light returned from said fluid sample;   converting the received spectral information into an electrical signal indicative of the received spectral information;   comparing the electrical signal to an algorithm built upon correlation with the analyte in the fluid sample; and   converting the received spectral information into the concentration of said analyte in said fluid sample via a central processing unit, the central processing unit controlling the light source and varying the intensity and timing of the delivery of said light within said predetermined wavelength range to improve the accuracy of conversion of the received spectral information into concentration of said analyte in said fluid sample.   
     
     
         18 - 50 . (canceled) 
     
     
         51 . A method for determining the concentration of an analyte in body fluid, the method comprising the acts of:
 delivering substantially monochromatic light using an infrared light source sequentially across a predetermined wavelength range;   contacting body tissue using a body tissue interface;   delivering light from said infrared light source to the contacted body tissue;   receiving light reflected from the body fluid;   converting the received reflected light into an electrical signal indicative of the received reflected light;   comparing the electrical signal to an algorithm built upon correlation with the analyte in the body fluid via a central processing unit; and   converting the received spectral information into the concentration of the analyte in said body fluid,   wherein the central processing unit controls said infrared light source and varies the intensity and timing of the delivery of said monochromatic light with the predetermined wavelength range to improve the accuracy of conversion of the received spectral information into concentration of said analyte in said fluid.   
     
     
         52 . The method of  claim 51  further including disposing an index matching medium disposed between the body tissue interface and the received body tissue, wherein the infrared light delivered to the body tissue and reflected by the body tissue passes through the index matching medium. 
     
     
         53 . The method of  claim 51 , wherein the infrared light has a wavelength ranging between approximately 1400 nanometers and approximately 2500 nanometers. 
     
     
         54 . The method of  claim 51 , wherein the intensity of said monochromatic light is uniform over said predetermined wavelength range. 
     
     
         55 . The method of  claim 51 , wherein the intensity of said monochromatic light is varied across said predetermined wavelength range to provide spectral information received from said sample having uniform intensity across said predetermined wavelength range. 
     
     
         56 . The method of  claim 51 , wherein said monochromatic light contains information that is used to correct for the effect on the light spectra of the sample, light delivery and collections systems and detector distortions. 
     
     
         57 . The method of  claim 51 , wherein said light source contains concentration-related spectra that correct for non-linear responses of the analyte.