Additively manufactured liquid metal–based piezoresistive device with dual functions of force sensing and mechanical energy absorption

Abstract

Although liquid metals are renowned for their exceptional stimulus-responsive properties, their potential for functionalization remains constrained when relying solely on simple deformations. Recent progress in additive manufacturing has enabled the simultaneous programming of both materials and structures, facilitating the development of various functional devices based on liquid metals. However, these devices typically exhibit only a single functionality. This work proposes an approach for the fabrication of multi-functional devices by uniformly coating GaIn liquid metal onto the surface of lattice structures produced via laser powder bed fusion. The resulting flexible piezoresistive device not only responds to pressure by altering its resistance but also exhibits significant mechanical energy absorption capabilities. Through comprehensive analysis of the device’s sensing performance and resistance variation during structural densification, we observed outstanding characteristics, including high sensitivity, a rapid response time of 58 ms, a maximum mechanical energy absorption capacity of 40.1 kJ·m⁻³, and a cycle life exceeding 12,000 cycles. Notably, a sudden change in resistance consistently occurs during the lattice structure’s densification process, making the device highly effective for protecting delicate components. This work extends beyond the intrinsic stimulus-responsive characteristics of liquid metals, presenting a strategy in the design and manufacturing of piezoresistive devices through material and structural innovation, with promising potential for a wide array of applications.