Through structure design, 3D printing enables the fabrication of mechanically durable superhydrophobic membranes with an ordered porous structure for oil–water separation.

Through applying the liquid metal and elastomer as the core and shell materials, respectively, a coaxial printing method is being developed in this work for preparing a stretchable and conductive cable. When liquid metal alloy eutectic Gallium-Indium is embedded into the elastomer matrix under optimized control, the cable demonstrates well–posed extreme mechanic performance, under stretching for more than 350%. Under developed compression test, the fabricated cable also demonstrates the ability for recovering original properties due to the high flowability of the liquid metal and super elasticity of the elastomeric shell. The written cable presents high cycling reliability regarding its stretchability and conductivity, two properties which can be clearly predicted in theoretical calculation. This work can be further investigated as a strain sensor for monitoring motion status including frequency and amplitude of a curved object, with extensive applications in wearable devices, soft robots, electronic skins, and wireless communication.

Materials with tunable and high strain sensitivities have a great potential to be used in next generation flexible electronic devices. Conventional methods, which focus on tailoring the material composition to obtain controllable sensitivities, face the issues of complicated fabrication process and instability, restricting their use in real applications. In this work, we propose the idea of tuning the sensitivities through precisely controlled micro-structures. Based on 3D printing technique, we successfully fabricate graphene/polydimethylsiloxane composites with long range ordered porous structures. The resultant composites present tunable and high gauge factors, along with excellent durability. The tunable sensitivity comes from different strain distributions on the composites under stretching, arising from the different micro-structures constructed. Taking full advantage of the composites in terms of sensitivity and durability, we demonstrate the application of the 3D printed porous sensors as wearable human motion detectors.

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