Electrical percolation network based on nano-cellulose template for flexible hydrogel bioelectrode.

Hydrogel based electrodes have been applied in the field of bioelectronics, which is of great significance for constructing a robust human-computer interface. However, achieving both reliable conductivity and tissue matching mechanical properties remains challenging. Here, we report a synergistic strategy for constructing a hydrogel electrode for bioelectronic interface with tissue modulus and high conductivity by bacterial cellulose (BC) template induced growth polypyrrole (PPy) electrical percolation network combining a polymethacryloyloxyethyl trimethyl ammonium chloride (PDMC) hydrophilic network. This strategy balances the modulus and conductivity of the bioelectrode, makes up for the adverse effect of the conductive filler on the mechanical properties of the hydrogel, and constructs an effective conductive pathway. The electrical percolation of the hydrogel can be achieved at a low permeability threshold, and the flexibility (E = 288 kPa) of the hydrogel electrode with high conductivity (135.75 S/m) can be obtained. Moreover, the hydrogel electrode has low interface impedance and superior charge storage and injection capability, which allows higher signal-to-noise ratio of recording epidermal electrophysiological signals than that of commercial electrodes. The conductive, flexible and biocompatible hydrogel prepared here provides a new way to construct reliable bioelectronic devices.