Medical Carbon-Dioxide Isotopic Ratio Microsensor

A noninvasive medical diagnostic instrument for the measurement of 12CO2/13CO2 isotope ration in human breath is needed for quick screening of glucose utilization, pancreatic and liver functions and certain infections of the digestive tract. The instrument proposed here relies on a novel laser source which generates middle-infrared radiation as a result of nonlinear frequency conversion of near-infrared diode laser beams in a microstructured nonlinear material. An integrated-optics approach to building miniature, highly sensitive and inexpensive middle-infrared laser gas sensor is described. In Phase I, we will demonstrate frequency conversion into the middle infrared region of highest CO2 absorption and investigate the detection sensitivity. During Phase II, we will build an optimized light source, incorporate it into a prototype medical 12C02/13CO2 sensor, and deliver the working prototype to the Air Force for testing.| Benefits: We will develop a miniature, narrowband laser source operating at room temperature in the middle infrared region and use it in a chip-size trace gas sensor. The sensor will be several orders of magnitude more sensitive than near infrared diode laser gas sensors and will be commercially applicable in medical diagnostics, industrial process control and environmental monitoring.|