On the Actuation of Thin Film Longitudinal Intrafascicular Electrodes

An important challenge for neural prosthetic research is to develop intimate and selective neural interfaces able to record and stimulate over long periods of time. To satisfy these requirements, recent studies have been investigating new approaches to develop advanced neural electrodes. In particular longitudinal intrafascicular electrodes (LIFEs) seem to be a suitable solution to contact the peripheral nervous system. However, they present some drawbacks in terms of robustness during chronic experiments. In this work we combined together two different approaches in order to address these issues: a new version of the LIFEs characterized by a flexible and light-weighted structure (named tf-LIFE) were integrated together with micro-actuators in order to obtain movable contacts. In particular, shape memory alloys (SMA) have been applied as smart actuators to move the contact points of the tf-LIFEs modifying their shape in a selective way. A "serpentine" like shape has been memorized into SMA thin films which have been covered by polyimide thin films to simulate the tf-LIFE structure. In parallel, SMA has also been glued directly to the electrode. The results of the characterization showed that flexible intrafascicular electrodes actuation by SMA could be a new promising technique to control the position of the active sites of the tf-LIFE inside the nerve, thus improving their performance for long-term applications