Microelectrochemical Multitransistor Devices Based on Electrostatic Binding of Electroactive Anionic Metal Complexes in Protonated Poly(4-vinylpyridine): Devices That Can Detect and Distinguish up to Three Species Simultaneously

Microelectrochemical multitransistor devices based on the reversible electrostatic incorporation of electroactive anionic metal complexes, such as IrCl₆²⁻, Mo(CN)₈⁴⁻, and Fe(CN)₆⁴⁻, into protonated poly(4-vinylpyridine) [(VPyH⁺)_n] can detect and differentiate between these species. Arrays of closely spaced, individually addressable, band microelectrodes are connected by (VPyH⁺)_n. Pairs of these microelectrodes are operated as independent microelectrochemical transistors. Each transistor shows high drain current only when its gate potential corresponds to the redox potential of a metal complex bound to the (VPyH⁺)_n, and this serves as the means of detecting and identifying the metal complex. Binding of anionic metal complexes in (VPyH⁺)_n is reversible, and therefore, the devices can be demonstrated to respond continuously to a flow of electrolyte in which the number and identity of the metal complexes is varied.