Double-barrell ion-sensitive microelectrodes with extra thin tip diameters for intracellular measurements.

A method has been described by which double-barrel ion-sensitive microelectrodes for intracellular measurements can be produced with a mean tip diameter of 0.1 micron. Potassium, calcium and chloride activity could be measured with these electrodes by means of ion exchangers and neutral ion carriers. The mean steepness for the potassium electrode is 50.16 mV, for the calcium electrode 24.7 mV and for the chloride electrode 39 mV. the drift of the electrodes varies between 2-4%/h. The mean response time amounts for the potassium electrode to 170 ms, for the calcium electrode to 350 ms and for the chloride electrode to 250 ms. With these electrodes it is possible to measure intracellularly cell membrane potential and ion activity simultaneously.