Flexible Graphene-Assembled Film-Based Antenna for Wireless Wearable Sensor with Miniaturized Size and High Sensitivity

The flexible radio frequency (RF) wireless antennas used as sensors, which can detect signal variation resulting from the deformation of the antenna, have attracted increasing attention with the development of wearable electronic devices and the Internet of Things (IoT). However, miniaturization and sensitivity issues restrict the development of flexible RF sensors. In this work, we demonstrate the application of a flexible and highly conductive grapheneassembled film (GAF) for antenna design. The GAF with a high conductivity of 106 S/m has the advantages of light weight, high flexibility, and superb mechanical stability. As a result, a small-size (50 mm x 50 mm) and flexible GAF-based antenna operating at 3.13-4.42 GHz is achieved, and this GAF antenna-based wireless wearable sensor shows high strain sensitivities of 34.9 for tensile bending and 35.6 for compressive bending. Furthermore, this sensor exhibits good mechanical flexibility and structural stability after a 100-cycle bending test when attached to the back of the hand and the wrist, which demonstrates broad application prospects in health-monitoring devices, electronic skins, and smart robotics.