Experimental Study of Microelectrode Array and Micro-Hole Array Fabricated by Ultrasonic Enhanced Micro-EDM

Abstract

Micro electrical discharge machining (EDM), enhanced with ultrasonic vibration, is explored and assessed as a method 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. In the process of reverse copying, the thicker rod electrode can not rotate, resulting in electric arc and short-circuit occurring easily, so it is necessary to add ultrasonic vibration on the plane plate electrode, in order to exclude debris as soon as possible and stabilize machining process. In the process of machining, four parameters, such as working voltage, working capacity, ultrasonic amplitude and holes spacing, are important to machining efficiency, each parameter has four typical values. In order to reduce experiment times, a scheme of orthogonal experiment was designed with different parameters combination. With result of experiments, the ratio of mean square deviation to error mean square deviation of each parameter was calculated and significance of each parameter was obtained, and the best parameters combination was asserted through theoretical calculation. Also, experimental study of using microelectrode array to machine micro-hole array by Micro- EDM was made and influence curve of each parameter was drawn. Finally, 5×5 arrays of microelectrode were obtained, the diameter of single electrode is less than about 30.m and heightto- width aspect ratios is more than 8, moreover, these microelectrode arrays have good coaxiality and surface quality.

Modeling Debris Motion in Vibration Assisted Reverse Micro Electrical Discharge Machining Process (R-MEDM)

“…To flush the debris from inter-electrode gap, techniques such as ultrasonic vibration assisted electrode [11], [12], jet flushing [13], magnetic field assistance [14], rotating electrodes and geometrically modified electrodes are used. Imparting ultrasonic vibration to electrode is considered to be the most efficient technique for dispelling the debris in micro EDM because other techniques are not as effective in flushing the debris due to smaller inter-electrode gaps.…”

Numerical Analysis and Experimental Study on Fabrication of High Aspect Ratio Tapered Ultrafine Holes by Over-Growth Electroforming Process

“…Up to now, several techniques have been exploited to fabricate these specially shaped holes: jet electrochemical machining [1], chemical or electrochemical etching [2,3], electro discharge machining [4], laser beam machining [5], and electroforming [6]. Although each of these techniques has its own unique advantages to shape them, comparatively, the electroforming technique is thought to be the most competitive one due to its diverse superi-orities, including ultrahigh dimensional accuracy, almost no cracks and burrs, smooth surface morphologies, accommodation to mass production, very small thermal stress, etc.…”

Experimental characterization of the reverse micro-electrodischarge machining process for fabrication of high-aspect-ratio micro-rod arrays

“…Arrayed micro-holes have been used in nozzle outlets to cool various electronic devices [15]. In the biomedical field, arrayed micro-holes have been used for single cell embryo manipulation [16] and to capture neural signals from a number of recording sites with a pre selected spatial distribution [17].…”

“…Typically, the process can generate intricate features or an array of micro-electrodes with high aspect ratios. These arrays can then be used as a tool for machining a micro-hole array using other process such as micro-ECM (electro-chemical machining) [17].…”