New micro-EDM reverse copying technology for microelectrode array fabrication

Micro electrical discharge machining (EDM), enhanced with ultrasonic vibration, is explored and assessed as a new technology for developing microelectrode array, for microelectrode array fabricated by LIGA has shortcomings such as complex technology and high price. Based on the mechanism of micro-EDM, micro-hole array discharges to fabricate microelectrode array by reverse copying. First, process for the Micro-EDM technology of reverse copying is planned. In the process of reverse copying, the thicker rod electrode can’t rotate, resulting in electric arc and short-circuit easily, so it is necessary to add ultrasonic vibration on the plane plate electrode. Then, influence of ultrasonic vibration is analysed from the way of vibration mechanics through theoretical analysis and experimental observation. Compared with machining without ultrasonic vibration, single discharging energy decreases 1/2, discharge frequency improves four times, machining efficiency increases two times and better surface quality is achieved. Finally, 3 × 3 arrays of microelectrode and micro-hole made by these microelectrode arrays are got, the diameter of single electrode is less than 30 μm and height-to-width aspect ratio is more than 10, moreover these arrays of microelectrode and micro-hole have very good surface quality.