Hydraulic-driven adaptable morphing active-cooling elastomer with bioinspired bicontinuous phases.

The active-cooling elastomer concept, originating from vascular thermoregulation for soft biological tissue, is expected to develop an effective heat dissipation method for human skin, flexible electronics, and soft robots due to the desired interface mechanical compliance. However, its low thermal conduction and poor adaptation limit its cooling effects. Inspired by the bone structure, this work reports a simple yet versatile method of fabricating arbitrary-geometry liquid metal skeleton-based elastomer with bicontinuous Gyroid-shaped phases, exhibiting high thermal conductivity (up to 27.1 W/mK) and stretchability (strain limit >600%). Enlightened by the vasodilation principle for blood flow regulation, we also establish a hydraulic-driven conformal morphing strategy for better thermoregulation by modulating the hydraulic pressure of channels to adapt the complicated shape with large surface roughness (even a concave body). The liquid metal active-cooling elastomer, integrated with the flexible thermoelectric device, is demonstrated with various applications in the soft gripper, thermal-energy harvesting, and head thermoregulation.

Ferromagnetic Liquid Metal Putty-Like Material with Transformed Shape and Reconfigurable Polarity.

It is remarkably desirable and challenging to design reconfigurable ferromagnetic materials with high electrical conductivity. This has attracted great attention due to promising applications in many fields such as emerging flexible electronics and soft robotics. However, the shape and magnetic polarity of existing ferromagnetic materials with low conductivity are both hard to be reconfigured, and the magnetization of insulative ferrofluids is easily lost once the external magnetic field is removed. A novel reconfigurable ferromagnetic liquid metal (LM) putty-like material (FM-LMP) with high electrical conductivity and transformed shape, which is prepared through homogenously mixing neodymium-iron-boron microparticles into the gallium-based LM matrix, and turning this liquid-like suspension into the solid-like putty-like material by magnetization, is reported to achieve this. The induction magnetic field of FM-LMP is mainly attributed to the magnetic alignment of the dispersed ferromagnetic microparticles, which can be conveniently demagnetized by mechanical disordering and reversibly reconfigured through microparticle realignment by applying a weak magnetic field. FM-LMP with a low fraction of microparticles can be used as printable conductive ink for paper electronics, which are further exploited for applications including magnetic switching, flexible erasable magnetic recording paper, and self-sensing paper-based soft robotics using magnetic actuation.