Functional liquid metal nanoparticles: synthesis and applications

Room temperature liquid metals are an emerging class of functional materials with applications in a variety of soft intelligent systems. In recent years, efforts have been made to integrate liquid metal alloys such as eutectic gallium-indium (EGaIn) and eutectic gallium-indium-tin (Galinstan) into wearable electronics, soft robotics, and biomedical devices. One main methodology is reducing the size of the liquid metal (LM) droplets to the micro and nanoscale level. In this review, we present an overview of the recent progress in synthesizing liquid nanoparticles with a focus on the role of processing parameters on their structure and surface properties. Next, the liquid metal nanoparticles are discussed as the functional units in polymer nanocomposites with enhanced electrical and thermal properties. Ultimately, the applications of LM nanoparticles and nanocomposites are presented, followed by a brief outlook on the challenges and future developments of advanced liquid metal material systems. Sonication and mechanical shearing are scalable processes for creating liquid metal nanoparticles. Optimizing the involved processing parameters is crucial for achieving the desirable structure, surface properties and applications of these nanoparticles.