Flexible EGaIn Liquid Metal Microstrip Patch Antenna Based Pressure Sensor

Abstract

This paper presents a dual-purpose flexible liquid metal microstrip patch antenna and pressure sensor that is able to sense physical deformation and also transmit data wirelessly. The antenna is built from polydimethylsiloxane (PDMS) with a top liquid metal electrode reservoir and a sealed bottom air cavity inside the PDMS structure. Eutectic Gallium Indium (EGaIn) liquid metal alloy in the electrode reservoir creates a stretchable, bendable, rollable, and twistable device, suitable for RF transmission and sensing environmental pressure variation. 3D printed molds are used for device fabrication. The realized antenna prototype is characterized and found to operate at a resonant frequency of 6.78 GHz, with a reflection coefficient and gain of -18.54 dB and 7.9 dBi, respectively. The pressure sensitivity of the antenna is measured as 47798 Hz/Pa, making it ideal for both pressure sensing and wireless data transmission applications.