An ultrastretchable seamlessly integrated contactless charging microsystem towards skin-attachable wireless microelectronics

For electronics to be wearable, contactless charging and overall deformability are necessary pre-conditions. However, the current heterogeneous integration based on different active materials and separate manufacturing often leads to mechanical mismatch. Here, we report an ultrastretchable all-in-one integrated MXene-based microsystem comprising wireless coils, micro-supercapacitors (MSCs) and strain sensors. The seamless configuration without any connecting interface dramatically improves the structural integrity of the microsystem, and a pre-crumpled structure endows it with superior stretchability. Attributed to these, our MSCs can be wirelessly charged in ~20 s under various types of deformation and are capable of powering strain sensors, responding rapidly to body motion signals. Moreover, the MSCs display a high specific capacitance of 76.82 F cm^-3, and superb mechanical stability with 98.5% capacitance retention after biaxial stretching 1000 cycles from 0% to 500% areal strain. Therefore, this work sheds new insights into design and implementation of skin-attachable wireless microelectronics.