An RF-telemetry system with shape memory alloy microelectrodes for neural recording of freely moving insects

A radio frequency (RF) telemetry system with a shape memory alloy (SMA) microelectrode was designed and fabricated. The total size and weight are respectively 15 mm/spl times/8 mm and 0.1 g, without a battery. Since the telemeter is small and light enough to be loaded on a small animal such as an insect with no restraint on motion, the system can be used for the neural recording of a freely moving insect. The SMA microelectrode, fabricated by using microelectromechanical systems (MEMS) technologies, can be easily attached to a nerve by electrically actuating the electrode structure, Moreover, it does not detach from the nerve during the insect's motion due to its clipping structure. The telemeter can transmit signals by frequency modulation (FM) transmission at 80/spl sim/90 MHz. The transmitted signals can be received up to about 16 m away from the telemeter with a high S/N ratio. The neural activity can be detected without attenuation by using an instrumentation amplifier with its input impedance set to 2 M/spl Omega/ at 1 kHz. The telemeter was loaded on a cockroach and the neural activity during a free-walk is measured through this telemetry system.