Soft electronics on asymmetrical porous conducting membranes by molecular layer-by-layer assembly

Achieving biological softness and flexibility has been a critical challenge for bio-electronic materials in areas of implantable bionic interfaces and wearable devices. Unlike inherently rigid electronic materials, bioengineered interfaces or scaffolds require stretchable softness as well as functional porosity for selective ionic transports. Toward this goal of providing electrically conducting biomaterials, we report ultrathin single-walled carbon nanotube (SWNT) layer coating on biodegradable polycaprolactone (PCL) membranes via layer-by-layer (LBL) assembly technique. The resulting membranes have unique, hierarchically structured 3D network of conductive paths around asymmetric nano-/micro-pores, providing softness as well as stretchable, anisotropic electrical conductivity. The strain sensors embedded on the membrane also demonstrate bending directional sensitivity as well as piezoresistivity with tunable Gauge Factor (GF) in the ranges of 513 with stretchability of up to 100%. Furthermore, these composite membranes are biocompatible as evident by neuronal cell attachment tests with in vitro PC12 cell lines. As follows, this newly developed implantable multifunctional membrane has considerable potential for applications in bioengineered devices such as mechano-sensitive artificial interfaces and skins. (C) 2017 Elsevier B. V. All rights reserved.