Optical chemo- and biosensors for use in clinical applications

The development of pH-based fibre-optic biosensors for penicillin, urea, creatinin and glucose and their uses in clinical applications are described. A simple but very efficient way of constructing biosensors is to immobilize an enzyme layer directly on the tip of a pH optode. Biosensors based on pH probes depend on critical factors such as the pH value and buffer ion concentration in the sample media. Since biosensors cannot be sterilized due to the instability of the biological component, they are normally integrated into flow-injection-analysis (FIA) systems. The complex signal is transformed and analysed by a computer system. Characteristic features of the FIA peak give information about the buffer capacity in the solution. With the help of intelligent computing (neural networks), it is possible to recognize these features and relate them to the respective buffer capacity to obtain more accurate values.