A three-dimensional shape memory alloy microelectrode with clipping structure for insect neural recording

A microelectrode, with clipping structure for neural recording from a free- moving insect, was designed and fabricated using a shape memory alloy (SMA) thin film. The SMA thin films (titanium nickel; Ti-48at, %Ni) are deposite d by RF magnetron sputtering and patterned by HF-HNO3 wet etching. The tran sformation temperatures of the SMA thin films were measured at 54 degrees C (A*) and 50 degrees C (M*). The SMA microelectrode consists of a degrees"h ook" structure (720 mu m x 480 mu m) and two "C"-shape probes (600 mu m x 7 0 mu m). The electrode impedance is about 5 k Ohm at 1 kHz, The desired thr ee-dimensional (3-D) shape is given to the electrode by a bonded wire, The clinging force of the electrode to the nerve is enhanced by the 3-D structu res. The SMA microelectrode can clip a nerve cord tightly. The damages of t he nerve by thermal actuation of the clip are not observed by physiological analysis, The neural activity from a living insect was successfully record ed with this SMA microelectrode. [423].