A comparative study of a polyindole-based microelectrochemical transistor in aqueous and non-aqueous electrolytes

The behaviour of a polyindole-based microelectrochemical transistor in aque ous and non-aqueous electrolytes is described. The polyindole film was grow n onto two closely spaced (100 mu m) platinum microelectrodes by anodic oxi dation of indole (10 mM) from 0.1 M tetrabutylammonium perchlorate in dichl oromethane at 1.1 V vs. Ag/AgCl. The polymerization was carried out for a s ufficiently long time in order to connect both Pt microelectrodes, which op erated as a transistor when immersed in an electrolytic solution. In this t ransistor, one microelectrode was a "source" and the other a "drain"; the A g/AgCl wire reference electrode was used as a "gate". The drain current (cu rrent between source and drain) was modulated by varying the gate potential (potential between source and gate) at a fixed drain potential (potential between source and drain). The transconductances of the transistor were est imated as 0.98 mS/cm and 20.6 mS/cm of channel width (separation between tw o microelectrodes) in aqueous and non-aqueous solutions, respectively.