ARRAYS OF GOLD MICROELECTRODES MADE FROM SPLIT INTEGRATED-CIRCUIT CHIPS

A simple and inexpensive way to fabricate arrays of gold microelectrod es is proposed. Integrated circuit chips are sawed through their middl e, normal to the longest axis, leading to destruction of the silicon c ircuit and rupture of the gold wires that interconnect it with the ext ernal terminals. Polishing the resulting rough surface converts the ti ps of the wires embedded in the chip halves into arrays of gold microd isks of about 25 mu m diameter. The number of active microelectrodes ( MEs), of an array depends on the number of pins in the chip, n, being typically (n/2)-4. These MEs can be used individually or externally in terconnected in any combination. X-ray images of the chips and microgr aphs of the resulting surface of the polished arrays have revealed var iable distances between neighbor MEs, which are, however, larger than 10 times the radius of the disks. This feature of the MEs prevents dif fusional cross-talk between electrodes. The use of these microdisk ele ctrodes for analytical purposes exhibits sigmoidal voltammograms, and chronoamperometric experiments confirm the nonlinear i vs. t(1/2) plot s, typical for processes where radial diffusion prevails. Satisfactory uniformity was observed for the response of each electrode of an arra y, indicating similarity of geometry and disk areas. The potentialitie s of these MEs were demonstrated by the determination of cadmium at pp b levels using square wave voltammetry with preconcentration. Due to t he relative ease with which these MEs can be manufactured and their go od performance in (chemical) analysis, wide applications in electroche mistry and electroanalysis is envisioned.