Dynamic Photomask-Assisted Direct Ink Writing Multimaterial for Multilevel Triboelectric Nanogenerator

Triboelectric nanogenerator (TENG) devices are extensively studied as a mechanical energy harvester and self-powered sensor for wearable electronics and physiological monitoring. However, the conventional TENG fabrication involving assembling steps and using the single property of matrix material suffers from simple devices shape and a single level of mechanical response for sensing and energy harvesting. Here, the printed multimaterial matrix for multilevel mechanical-responsive TENG with on-demand reconfiguration of shape is reported. A multimaterial 3D printing approach by using dynamic photomask-assisted direct ink writing printing together with a two-stage curing hybrid ink is first developed. Multimaterial structures with location-specific properties, such as tensile modulus, failure stress, and glass transition temperature for controlled deformation, crack propagation path, and sequential shape memory, are directly printed. The printed multimaterial structure with sequential deformation behavior is used to fabricate a multilevel-TENG (mTENG) device for multiple level mechanical energy harvesters and sensors. It is demonstrated that the mTENG can be embedded in shoe insoles to achieve both comfortable wearing and motion state monitoring. This work provides a new approach to combine multimaterial 3D printing with TENG devices for functional wearable electronics as energy harvester and sensors.