Double-microcrack coupling stretchable neural electrode for electrophysiological communication

Abstract

Developing neural electrodes with high stretchability and stable conductivity is a promising method to explore applications of them in biological medicine and electronic skin. However, considering the poor mechanical stretchability of typical conductive materials, maintaining the connection of electrode conductive paths under high stretching is still a challenge. Herein, for the first time, a double-microcrack coupling strategy for highly stretchable neural electrodes is proposed. Compared with single-layer stretchable microcrack electrodes, the design utilizes the complement between two gold microcrack films to contribute more conductive paths. It shows that the resistance change (R/R0) of the electrode under 100% strain is about 5.6 times, which is much lower than other electrodes and exhibits a high stretchability of ≈200%. Simultaneously, this design is an encapsulation-free design which avoids the electrode performance degradation caused by encapsulation. Furthermore, it is found that the adhesion strength between metal electrode and substrate is critical to the stretchability and stability of electrodes, so polydimethylsiloxane0.9-isophorone diisocyanate elastomer (PDMS0.9-IPDI), whose adhesion to gold electrode is 4.5 times higher than that of the commercial polydimethylsiloxane (PDMS), is synthesized. Finally, the electrophysiological communication between different organisms by electrodes is successfully demonstrated.