A FIBEROPTIC CHEMICAL SENSOR WITH DISCRETE SENSING SITES

A LONG-standing goal of clinical medicine has been the continuous, in situ measurement of solute concentrations (such as pH, pCO2 and pO2), particularly in blood. Blood monitoring is accomplished at present by analysing discrete samples at a centralized, remote clinical laboratory, causing delays between sampling and analysis. Most multi-analyte sensors developed for 'bedside' in situ monitoring 1 consist of several sensors fabricated into a sensor array or bundle 2,3. This approach is not ideal where sensor size is an important factor. Here we describe a technique that enables the development of a compact, multi-analyte fibre-optic chemical sensor. The technique is based on localized photopolymerization of appropriate dye indicators on the face of an imaging fibre. The sensing sites fluoresce to a degree controlled by analyte concentration, intensities being monitored simultaneously with an enhanced charge-coupled device (CCD) video camera. We present results from a sensor that contains three individual pH-sensitive areas, and indicate how multi-analyte sensitivity may be achieved.