Patent ID: 7004909
Filing Date: 2006-02-28
Classification: A61B,G01N

Abstract:
1. A diagnostic method for high sensitivity detection of component concentrations in human gas emissions comprising: (a) collecting a gas sample in a gas cell, wherein the gas sample may contain a specified component being associated with a plurality of fundamental absorption peak frequencies, and placing the gas cell in an optical cavity; (b) passing, at distinct and different times, a tunable optical radiation beam at a first frequency and at a second frequency through the gas cell when the gas cell (1) contains a reference sample having a known concentration of the specified component, (2) does not contain the specified component, and (3) contains the gas sample, wherein the first frequency corresponds to one of the fundamental absorption peak frequencies and the second frequency does not correspond to one of the fundamental absorption peak frequencies; (c) measuring, after the tunable optical radiation beam passes through the gas cell, as first signal outputs a power of the tunable optical radiation beam at the first frequency when the gas cell contains the reference sample, as second signal outputs the power of the tunable optical radiation beam at the second frequency when the gas cell contains the reference sample, as third signal outputs the power of the tunable optical radiation beam at the first frequency when the gas cell does not contain the specified component, as fourth signal outputs the power of the tunable optical radiation beam at the second frequency when the gas cell does not contain the specified component, as fifth signal outputs the power of the tunable optical radiation beam at the first frequency when the gas cell contains the gas sample, and as sixth signal outputs the power of the tunable optical radiation beam at the second frequency when the gas cell contains the gas sample; and (d) determining a concentration of the specified component in the gas sample using the following equation: where C corresponds to the concentration of the specified component, S 1 (0) corresponds to the third signal outputs, S 2 (0) corresponds to the fourth signal outputs, S 1 (SC) corresponds to the fifth signal outputs, S 2 (SC) corresponds to the sixth signal outputs, and constant 1 is determined by solving the equation for constant 1 and substituting the first signal outputs for S 1 (SC), the second signal outputs for S 2 (SC), and the known concentration of the reference sample for C.