Noninvasive mid-infrared in vivo glucose sensor

Abstract

A noninvasive mid-infrared in vivo glucose sensor for use in connection with the skin of a test subject is disclosed. The sensor includes a mid-infrared light source configured to deliver a light beam to the skin of the test subject, a collector element configured to collect backscattered light from the skin and direct it to the detector, and a detector element configured to measure the collected backscattered light from the skin. The mid-infrared light source may be a quantum cascade laser. The sensor may include optical fibers configured to deliver the light beam to the skin of the test subject. The collector element may be an integrating sphere or a bundle of two or more optical fibers. The sensor may also include a probe containing or connecting to optical fibers coupled to the mid-infrared light source and configured to be placed on the skin to take glucose level readings.

What is claimed is: 
     
         1 . A method for noninvasively measuring in vivo blood glucose concentrations from the skin of a test subject, the method comprising:
 irradiating the skin with a mid-infrared light source;   collecting mid-infrared backscattered light from the skin with a collector element, the collected backscattered light comprising a plurality of wavelengths;   directing all of the collected backscattered light to a detector without passing through a filter; and   comparing the strength of the signal received in a defined region by the detector with a calibration curve for that defined region.   
     
     
         2 . The method according to  claim 1 , wherein the mid-infrared light source is tuned to between around 1000 cm −1  to around 1200 cm −1 . 
     
     
         3 . The method according to  claim 1 , wherein the mid-infrared light source is tuned to between around 1040 cm −1  to around 1180 cm −1 . 
     
     
         4 . The method according to  claim 1 , wherein the defined region comprises wavenumbers between around 1070 cm −1  to around 1090 cm −1 . 
     
     
         5 . The method according to  claim 1 , wherein a distance between the collection device and the skin is between 1 μm and 100 mm. 
     
     
         6 . The method according to  claim 1 , wherein a distance between the collection device and the skin is between 100 μm and 20 mm. 
     
     
         7 . The method according to  claim 1 , wherein a distance between the collection device and the skin is between 1 mm and 10 mm. 
     
     
         8 . The method according to  claim 1 , further comprising collecting the mid-infrared backscattered light from the skin with a probe containing or connecting to optical fibers coupled to the mid-infrared light source. 
     
     
         9 . The method according to  claim 8 , wherein the probe is configured to be placed on the skin of the test subject to take glucose level readings. 
     
     
         10 . The method according to  claim 8 , wherein the optical fibers are hollow core optical fibers. 
     
     
         11 . The method according to  claim 1 , wherein the mid-infrared light source is configured to provide a peak power greater than 100 milliwatts and an average power of less than 10 milliwatts. 
     
     
         12 . The method according to  claim 1 , wherein the mid-infrared light source is a quantum cascade laser. 
     
     
         13 . The method according to  claim 1 , wherein the collector element is an integrating sphere. 
     
     
         14 . The method according to  claim 1 , wherein the collector element is a bundle of two or more optical fibers.