MICRO ION-SELECTIVE ELECTRODES BASED ON ACTIVATED CARBON FIBERS

Abstract

Conventional potentiometric microelectrodes which are used as reference and/or ion-selective electrodes for biomedical and physiological applications are usually based on glass capillary supports. They can be made with a tip diameter of approximately 1 pa by using a special glass capillary-pulling equipment. The resulting resistance of the glass capillary tip is >100° \m and the relatively high distributed capacitance across the glass capillary wall which separates the interior solution from the outside solution causes the long time constant and a low signal/noise ratio of these microelectrodes. This can cause problens if fast changes in ion concentration have to be measured, as for example during the electrostimulation of cells.