Examples of the application of light-tissue interaction to biomedical engineering

The subject of this paper relates to the measurable effects of light behavior in biological materials. The problems considered include some current topics concerning the achievements and still ongoing development in the selected fields of light-tissue interaction to be used in biomedical measurements. Measurable effects of interaction between light and tissues may be utilized in biomedicine with emission, reflection or transmission modes, respectively. The latter is especially considered in this paper: transillumination as the method of examination by the passage of light through tissues or a body cavity is a diagnostic technique in the course of intensive development at the moment. Red light and near-infrared radiation emitted by high-efficient LEDs can be noninvasively transmitted through the blood-supplied tissues. Some representative examples of the medical applications of non-invasive effects of light-tissue interaction are discussed. Under the transillumination and illumination from underneath, it is possible to diagnose and monitor the parameters of tissues and organs examined. This paper includes discussion of selected issues related to the biophysical and optical phenomena used and examples of practical applications of tissue transillumination techniques. The authors briefly report the current state-in-the-art and also present their own results. Among other things, the presented examples include: optoelectronic techniques used in monitoring of living tissue vitality, and promising results obtained during preliminary experiments with transillumination scanning applied to fingers of the human hand.