IR-biosensor: flat silver halide fiber for bio-medical sensing?

Cylindrical optical fibers, made of Various materials, have been used for d ecades for chemical and biological sensing. Optical fibers transparent in t he mid-infrared (IR) enable absorption measurements in remote locations. Ne w techniques will enable the use of IR fibers for measurements in ATR-mode. If the fiber is in contact with a sample that has characteristic absorptio n 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 proves that flattened silver halide fibe rs could be useful as sensing elements in analytical systems. First measure ments using flattened IR-fibers have been carried out on biological targets . The experimental set-up used was made up of an FTIR-spectrometer, fiber o ptic cables and an external detector. A segment of 1.9 cm at the center of the fiber was flattened to approximately 100-150 mum. Transmission spectra of flattened fibers have been compared to those of the cylindrical fibers. IR-spectra were recorded for biochemical compounds such as glucose, bovine serum albumin (BSA), gelatin and bio-fluids, and native tissue was compared to coagulated tissue. Spectral differences were obtained indicating a poss ible use for the study of thermal damage in tissues. (C) 2001 Elsevier Scie nce B.V. All rights reserved.