Mechanical Gradients Enable Highly Stretchable Electronics Based on Nanofiber Substrates

Stretchable electronics play a pivotal role in the age of information and intelligence. Integrated circuit components are an integral part of high-performance and multifunctional stretchable electronic devices. Therefore, it is an ideal design concept for stretchable electronic devices to not only ensure the reliability of the connection between rigid inorganic electronic components and stretchable circuits but also maintain the stretchability of the device. In this work, we constructed a mechanical gradient strategy to fabricate high-performance stretchable electronic devices. Briefly, polyvinyl alcohol glue is used to fix integrated circuits on stretchable circuits, which are fabricated by printing liquid metal on a thermoplastic polyurethane nanofiber membrane. The strategy of integrated circuits (rigid)-polyvinyl alcohol glue (high elastic modulus)-thermoplastic polyurethane nanofiber membrane (low elastic modulus)-liquid metal (liquid) realizes the strain gradient during the stretching process of the device, thus ensuring the stability and reliability. Moreover, we explored the mechanism through experiments and finite element analysis. The flexible electronic devices fabricated by this scheme are not only ultra-stretchable (900%) but also have good stability and comfort. As proof, the application in stretchable sensors, human-computer interaction devices, and displays was realized.