This Small Business Innovation Research Phase I project aims to develop compact and low cost instruments to measure tissue oxygenation based on near-infrared (NIR) spectroscopy. NIR light in the .7-1.1 Um range penetrates human tissue to a depth of several centimeters, and is attenuated during transmission by oxyhemoglobin, deoxyhemoglobin, melanin, water and cytochrome aa3, each with its own characteristic absorption spectrum. NIR absorption spectroscopy offers a number of advantages in comparison with other oxygen measurement modalities: it is non-invasive, uses non-ionizing radiation, offers high spatial and temporal resolution, and supplies new types of metabolic and functional information for low cost, rapid, bedside diagnostic procedures. The Phase I project will determine the most practical means to implement a hand-held NIR spectroscopic oxygenation monitor,k specify the components needed, define the measurement method and assess the practicality of the instrument for Phase II development.