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×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 80~90 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 MΩ at 1 kHz. The telemeter was loaded on a cockroach and the neural activity during a free-walk is measured through this telemetry system