Development of chronic longitudinal intrafascicular electrodes

Longitudinal intrafascicular electrodes (LIFE) are fine electrodes threaded into the extracellular space between axons in peripheral nerves or spinal roots. The authors are developing these electrodes for application in FES. An area of concern is the possibility of EMG and other external noise sources masking the recorded neural signals. Prior experience with LIFEs have shown that external noise can be reduced by using differential bipolar recordings. In the present study the authors characterize this effect in acute animal experiments to determine an optimal electrode geometry for chronic implants. The authors find that the maximal signal-to-noise ratio is achieved with electrode spacings of between 1-2 mm