Microelectrodes pipette filling

The earliest type of ionophore-based potentiometric microelectrodes were prepared in the mid 1970s from micrometer-sized glass pipettes, filled at the end with the ionophore-doped hydrophobic phase (Figure 16). " For speciality applications, in particular, in biochemical and medical research, these microelectrodes continue to have a variety of applications. Particularly noteworthy are then-use to study intracellular ion concentrations, the release and uptake of ions into ceUs, and their recent use as... 

Whether metal or fluid-filled microelectrodes are used, the interface effect is still felt. In the case of metallic electrodes, the interface occurs at the active surface of the electrode. With fluid-filled micropipettes, the metal-electrolyte interface exists in the pipette stem where electrical connection is made to the recording or stimulating electronics. There is the additional complication of a two-electrolyte interface at the electrode tip, since the electrolyte filling the lumen is usually different from the external electrolyte. 

A specialized microelectrode-type electrode was developed by Florey and Kriebel (1966) for use in certain types of neurological recording. The structure is basically a suction pipette as shown in Figure 8.6a. The tip of the electrode is made slightly smaller in internal diameter than the diameter of the axon or nerve bundle being studied. The electrode assembly is filled with isotonic solution and suction applied to the nerve end until the desired... 

TABLE III. Data from intracellular measurements in frog heart muscle made with chloride microelectrodes and KCl filled micro-pipettes. Entries are mean values plus or minus the standard error of the mean. 

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