A Soft and Conformal Cuff Electrode for Selective Stimulation of the Sciatic Nerve in Pigs

Electrical stimulation of the peripheral nervous system (PNS) in humans shows beneficial results in treating various diseases and disorders. These treatments could be improved by stimulation of individual fascicles within the nerve with selective multi-electrode neural cuffs.<br/><br/>The four main challenges with cuff electrodes for selective PNS stimulation are (i) reducing device dimensions (increasing the number of electrodes), (ii) improving biocompatibility, (iii) reducing mechanical mismatch to tissue (and thus the foreign body reaction) and (iv) preventing leaking current (through the gap between electrode and nerve).<br/><br/>To address these challenges, we have developed a stretchable multi-electrode cuff that can be wrapped around peripheral nerves in large animals. The cuff shows close conformability to the nerve, thereby reducing leaking current and increasing specificity. The superior conformability stems from the cuffs low Young’s modulus of 800 kPa and small device thickness of 50 µm. The cuff electrode consists of a patterned gold nanowire composite in an encapsulating matrix of biocompatible and stretchable silicone (poly(dimethylsiloxane)). The eight stimulation electrodes incorporate a high surface-area platinum coating, ensuring optimal charge transfer to the nerve.<br/><br/>Our stretchable multi-electrode cuff was successfully used in a pig sciatic nerve model, where it was able to selectively activate four separate leg muscles in the pig.<br/><br/>Our stretchable multi-electrode cuff clearly shows the benefit of small device dimension and conformability for selective PNS stimulation. Furthermore, the cuffs inherently soft and biocompatible components have the potential to prevail in the chronic applications needed for selective PNS stimulation treatments in humans.