Pulsed Laser Modulated Shock Transition from Liquid Metal Nanoparticles to Mechanically and Thermally Robust Solid-Liquid Patterns.

In this work, a general mechanism is discovered to form liquid-metal-based, stable and stretchable conductive patterns on rigid and soft substrates. It is discovered that pulsed laser irradiation of liquid metal nanoparticles (LMNPs) with tunable conditions can induce transformation to stable and stretchable solid-liquid (S-L) dual phases on various surfaces. Formation of this unique solid-liquid composite phase is the key to change the wetting behavior of the conductive patterns on various substrates and enables mechanically stable patterns on various substrates. Pulsed-laser-driven thermo-mechanical shock momentum is important for rupture and joining of the LMNPs, providing much better control than the traditional mechanical sintering. The solid nanophase forms a nanoporous matrix filled with and wetted by the LM, thereby providing a stabilization mechanism for the S-L composite patterned thin film. The mechanical and thermal reliability of the solid-liquid patterns is investigated. The S-L patterns can stretch up to 30% strain and cycle stably for 7000 cycles. It can be heated up to 177 °C with an input power of 0.58 W. The solid-liquid composite film provides great opportunity for various applications as a flexible conductor with unique mechanical and physics properties and further inspires design of LM devices for completely exposed applications.