Two-Terminal Microelectrochemical Diode with Contact Spacing of about One Micron. A Device Based on One Solution Redox Couple and One Electrode-Confined Redox Couple

摘要

A microelectrochemical diode can be fabricated by functionalizing one of two identical, adjacent platinized Au microelectrodes of an eight electrode microelectrode array with a redox polymer, (BPQ(2+)/(+)n), derived from an N,N'-dibenzyl-4,4'-bipyridinium monomer. The microelectrode array consists of eight Au microelectrodes each about 50 microns long, 2.3 microns wide, and 0.1 microns thick and separated from each other by about 1.3 micron. The array is fabricated on a Si3N4 surface chemically deposited on a Si/SiO2 substrate using conventional microfabrication procedures. Diode behavior is found in aqueous electrolyte solution containing the Ru(NH3)6(3+)/(2+) redox couple which responds reversibly at a platinized Au electrode. Rectifying behavior is obtained, because a micro electrode modified with greater than approx. 0000000001 mol/sq cm of the ((BPQ(2+)(+))n) polymer is capable of reducing the oxidized form of the redox couple (Ru(NH3)6(3+)) but is incapable of oxidizing the reduced form of the redox couple (Ru(NH3)6(2+)). When the negative lead of a power supply is attached to a (BPQ(2+)/(+)n)-derivatized microelectrode and positive lead is attched to an adjacent, naked microelectrode current flows when the applied potential approaches the difference in the formal redox potentials of the Ru(NH3)6(3+)/(2+) and (BPQ(2+9/(+)n redox couples, about 0.4 V. When the potential is applied in the opposite sense, no current flows.