Noninvasive Sensor for Measuring the Partial Pressure of Oxygen in Humans

The air of this proposal is to develop a noninvasive probe that may be placed near, but not on, the patient or the patient's wound, to measure the partial pressure of dissolved oxygen in the interstitial body fluids. The sensor is capable of assessing gas pressure levels in a graduated fashion from superficial to deep, in both healthy and compromised tissues. The sensitivity is sufficient to monitor wound healing in patients receiving hyperbaric oxygen therapy. The sensor is a laser diode transillumination spectrometer tuned to the near infrared 762 nm wavelength, the resonance wavelength of molecular oxygen. A vertical cavity surface emitting laser (VCSEL) is utilized as the 762 nm light source because they are tunable, stable, small, low cost and will operate off a single 9V battery. The sensor is expandable to measure carbon monoxide (CO) and carbon dioxide (CO2) with the addition of 1567 nm (CO) and 1573 nm (CO2) laser diodes. The Phase I project will determine the most practical means to implement a hand-held NIR spectroscopic oxygenation monitor, specify the components needed, define the measurement method and assess the practicality of the instrument for Phase II development.