Scanning electrochemical microscopy. 32. Gallium ultramicroelectrodes and their application in ion-selective probes.

Gallium ultramicroelectrodes for amperometric measurements in scanning electrochemical microscopy were fabricated by introduction of liquid Ga into drawn glass micropipets. Cyclic voltammetry of Ru(NH(3))(6)(3+) and the use of this species for SECM imaging is described. Double-barrel micropipet tips with a Ga amperometric electrode and an ion-selective (K(+)) potentiometric probe can also be constructed. This probe was used to image the K(+) activity near a 20-μm-diameter lumen of a glass capillary.