Liquid Metal Composite-Based Flexible Pressure Sensors with High Sensitivity

Abstract

In this study, we present a novel capacitive flexible pressure sensor incorporating a liquid metal composite-based micropillar dielectric structure. The micropillar array was fabricated using UV laser etching, a simplified and efficient alternative to conventional lithographic techniques, significantly reducing processing time and complexity. To enhance the effective dielectric constant variation under applied pressure, we incorporated a gallium-based liquid metal (EGaIn), which features a low melting point (T_m = 15.5 °C), high electrical conductivity (3.4 × 10⁶ S/m), and low toxicity. The sensitivity and pressure range of the sensor were systematically analyzed as a function of EGaIn content and micropillar aspect ratio (AR). The optimized sensor, with 15 vol % EGaIn and an AR of 1, demonstrated a high sensitivity of 2.07 kPa^-1 in the low-pressure regime (<135 Pa). These results highlight the potential of the proposed liquid metal composite-based capacitive pressure sensor for applications requiring high-performance pressure sensing, such as electronic skin, augmented/virtual reality systems, and health monitoring applications.