Solvent-Free Dry Friction-Enabled Self-Stabilized Liquid Metal Micro/Nanoparticles Toward Stretchable Electronics

Liquid metal (LM) combines high electrical conductivity with fluidic deformability, making them promising for conductive inks, stretchable networks, and composite sensing materials. In practice, bulk LM is transformed into micro/nano-particles (LMPs) to improve stability and processability for composites. LMPs are typically prepared via shear, ultrasonication, or microfluidics in liquid media, requiring subsequent processing to obtain dry particles. Herein, inspired by friction-induced aggregation during cream application, a dry-state friction strategy is developed for solvent-free fabrication of LMPs. During friction, bulk LM is continuously fragmented, while freshly exposed surfaces rapidly oxidize in air to form robust shells. Unlike conventional liquids, which rapidly coalesce after shear, this structure prevents re-coalescence, yielding stable core-shell LMPs. Particle size can be tuned by adjusting friction parameters, including pressure, speed, and duration, and alkaline surface modification enables control over morphology and oxide shell thickness. The as-prepared LMPs exhibit excellent stability in air and liquid, with no corrosion of metal substrates. Incorporation into a polyvinylpyrrolidone (PVP)-fructose matrix produces a sensing gel with stable electromechanical response, good durability, and degradable and recyclable characteristics. This work provides a simple route for LMPs, advancing their use in wearable sensors and soft electronics.