2019-05-06

Strategy of Constructing Light-Weight and Highly Compressible Graphene-Based Aerogels with an Ordered Unique Confifiguration for Wearable Piezoresistive Sensors

ABSTRACT: Three-dimensional (3D) graphene aerogels (GAs) have attracted huge attention from researchers due to their great potential in vast applications. The hydrothermal reaction combined with freeze-drying using graphene oxide (GO) as a precursor has proven to be an effffective method for obtaining relatively well-structured pure GAs. However, insuffiffifficient mechanical strength and low compressibility of the materials still limit their practical applications. Here, we report the microstructure-induced strong mechanical anisotropy of these monolithic GAs in transverse direction (TD) and longitudinal direction (LD), which has never been considered to be related to structural vulnerability. To overcome this anisotropy and enhance the structure, we hereby introduce our self-made poly(vinyl alcohol)-co-polyethylene (PVA-co-PE)nanofifibers and low-molecular weight PVA as structural enhancers into the original 3D network to form a novelnanofifiber−graphene composite aerogel. Intriguingly, a unique confifiguration is formed in the GA, in which the highly aligned stacked reduced GO sheets serve as the framework (cellular walls) and the nanofifibers act as cross-linking columns anchored between the walls to support the structure along the TD, whereas the micro/nanosized PVA lamellae serve as binders. The resulting aerogel (referred to as graphene−PVA-co-PE nanofifibers−PVA aerogel (GNPA)) has excellent compressive resilience along the TD and exhibits an ultrahigh gauge factor (14387%) at a very subtle strain (0.23%) in piezoresistive properties. The GNPA-TD has also been assembled into a variety of wearable sensors and demonstrates great potential for wireless human pressure sensing. In short, this study offffers an extremely simple and effffective method for developing graphene aerogels with a strong mechanical structure and paves the way for the application of 3D graphene in wearable sensors.

He Xiaowei, et al.Strategy of Constructing Light-Weight and Highly Compressible Graphene-Based Aerogels with an Ordered Unique Configuration for Wearable PiezoresistiveSensors. ACS applied materials &interfaces, 2019, 11, 19350-19362.