Highly Sensitive and Omnidirectionally Stretchable Bioelectrode Arrays for In Vivo Neural Interfacing.

Flexible electrode array, a new-generation neural microelectrode, is a crucial tool for information exchange between living tissues and external electronics. Till date, advances in flexible neural microelectrodes have been limited because of their high impedance and poor mechanical consistency at tissue interfaces. Here we introduce a highly sensitive and omnidirectionally stretchable polymeric electrode array (PEA). Micropyramid-nanowire composite structures are constructed to increase the effective surface area of PEA, achieving an exponential reduction in impedance compared with gold (Au) and flat polypyrrole (PPy) electrodes. Moreover, for the first time, we design a suspended umbrella structure to enable PEA with omnidirectional stretchability of up to ∼20%. The PEA can withstand 1000 cycles of mechanical loads without decrease in performance. As a proof of concept, PEA are conformally attached to a rat heart and tibialis anterior muscle, and electrophysiological signals (electrocardiogram and electromyogram) of the rat are successfully recorded. Our strategy provides a new perspective toward highly sensitive and omnidirectionally stretchable PEA that can facilitate the practical application of neural electrodes. This article is protected by copyright. All rights reserved.