Stretchable alternating current electroluminescent display is an emerging form of light-emitting device by combining elasticity with optoelectronic properties. The practical implementations are currently impeded by the high operating voltages required to achieve sufficient brightness. In this study, we report the development of dielectric nanocomposites by filling surface-modified ceramic nanoparticles into polar elastomers, which exhibit a series of desirable attributes, in terms of high permittivity, mechanical deformability, and solution processability. Dielectric nanocomposite effectively concentrates electric fields onto phosphor to enable low-voltage operation of stretchable electroluminescent display, thereby alleviating safety concerns toward wearable applications. The practical feasibility is demonstrated by an epidermal stopwatch that allows intimate integration with the human body. The high-permittivity nanocomposites reported here represent an attractive building block for stretchable electronic systems, which may find broad range of applications in intrinsically stretchable transistors, sensors, light-emitting devices, and energy-harvesting devices.

A stretchable alternating current electroluminescent display seamlessly combines the light-emitting capabilities with mechanical compliance, which offers exciting opportunities for applications in wearable gadgets, soft robots, and fashion designs. The widespread adaption to deformable forms of optoelectronics is currently impeded by the tedious and labor-intensive fabrication process. This study reports an efficient and scalable procedure to create a fully screen-printed, multicolor, and stretchable electroluminescent display. The as-prepared device exhibits excellent deformability and low-voltage operation. The practical implementation is demonstrated by creating a wearable sound-synchronized sensing system with an epidermal display responsive to the rhythm of music. The ink formulation and printing procedure developed here pave the way for convenient fabrication of stretchable electronic devices.

Solvent responsive hydrogel is a kind of intelligent soft material, which can be used in soft robots. Currently, most of the solvent responsive hydrogels are based on pure organic materials which has limited stiffness for actuations. Herein, a novel organic-inorganic composite hydrogel is designed and prepared. Calcium phosphate oligomers (CPO) nanoclusters are incorporated in polymer solution containing polyvinyl alcohol (PVA) and sodium alginate (SA) to form organic-inorganic hybrid copolymer suspensions. The solvent responsive hydrogel is simply prepared using co-evaporation method by optimizing the components in the colloid system. The inorganic nanoparticles work as the scaffold in the porous PVA network and the evaporation caused nonuniformity distribution further induces the formation of heterostructure, which has different shrinkage ratios along the thickness direction. The prepared hydrogel demonstrates excellent shape memory property by changing the environmental solvents between water and ethanol and its repeatability is also verified. The stiffness of hydrogel is enhanced and it has large deformation after incorporation of calcium phosphate nanoparticles. The bending angle of hydrogel can be well controlled by different water to ethanol ratios, allowing for underwater actuation. The functionality of an artificial gripper based on responsive hydrogel with high stiffness is demonstrated to transfer objects in ethanol. The design of organic-inorganic composite hydrogel with high stiffness may provide new insights for preparation of intelligent soft materials for underwater applications.