IR-spectroscopy: New results due to fiber optic sensing in view of biomedical application

Optical fibers transparent in the mid-infrared (IR) enable absorption measurements in remote location. New techniques will enhance the possibility using IR fibers for measurements in ATR-mode. If the fiber is in contact with a sample that has characteristic absorption lines, the total transmission of the fiber and sample of these lines will decrease. In this way the absorption of a sample can be determined using a non-destructive method. This work has proven the suitability of flattened IR-Fiber as a tool for detection of organic substances. Initial investigations using bio-organic compounds, bio-liquids, tissue in the native and coagulated state, and micro-organisms have already been carried out with a view to bio-medical usage. An experimental set up was based on an FTIR-spectrometer, fiber optic cables and an external detector. A segment of 1.5 cm at the center of the fiber was flattened to approx. 150 micrometers. Transmission spectra of flattened fibers have been compared to those of the cylindrical fibers. Spectral differences were obtained indicating a possible use for the study of thermal damage in tissues.