Flexible parylene-based microelectrode arrays for high resolution EMG recordings in freely moving small animals.

We present the development, fabrication and in vivo testing of a minimally invasive microelectrode array intended for high resolution multichannel recordings of electromyographic (EMG) signals. Parylene C was chosen as the structural substrate for its mechanical, electrical and physical properties. In particular, the device is extremely flexible. This provides a highly conformal coverage of the muscle surface and, at the same time, some degree of strain relief against the forces of micro-motion between the electrode and the surrounding tissues. By flexing and shaping itself to the muscles, the array is capable of maintaining a more stable electrical contact resulting in a significantly improved signal to noise ratio (SNR). To yield high signal selectivity, the design of the microelectrode array has been custom tailored to match the muscle anatomy of a particular animal system, the tobacco hornworm Manduca sexta. However, using the same fabrication protocol but different design parameters, the microdevice presented here can be easily implemented to study motor control and motor coordination in a vast range of small animals.