Towards high aspect ratio tungsten Micro Electrode Array for neural recording and stimulation applications

The design and fabrication of high aspect ratio microelectrode array is described. 10 × 10 array of electrically isolated square columns was fabricated using μ-wire Electrical Discharge Machining (EDM) from pure tungsten block. The square columns were machined to be of length 5 mm and width 200 μm with pitch 400 μm. The Utah Electrode Array [1] design was adapted in building this array. The array of square columns was later etched electrochemically to form an array of tapered/needle-shaped electrodes. Epoxy resin, EPOTEK 354, was used to isolate the individual electrodes at the base of the electrodes. Accelerated leakage current across this epoxy in simulated physiological environment was measured to test its long term stability. Variations of this array design can be built using the developed techniques for use of such arrays in intracortical and peripheral nerve recording and stimulating applications.