Flexible electronics substrate with excellent tear-resistant and high toughness using multi-material 3D printing

Polydimethylsiloxane (PDMS) with excellent stretchability and biocompatibility, has been widely used as a flexible substrate for wearable and stretchable electronics. However, the drawback of poor tear resistance of PDMS greatly limits its applications, such as flexible electronics. Herein, a gradient structure Ecoflex-PDMSEcoflex (E -P -E) combining PDMS and Ecoflex was proposed by combining multi -material 3D printing with functional gradient material design to improve the tear resistance of flexible substrates. The E -P -E gradient structure substrate has a 73 times increase in fracture energy and a 7 times increase in tear strength compared with conventional PDMS substrates. Liquid metal -based strain sensors made with our designed E -P -E gradient structure substrate can be directly worn on the finger with low hysteresis (0.47%), good cyclic stability (0.04% change in sensitivity after 1000 cycles of 100% strain), and high strain range (>180%), which showed a broad application prospect in the fields of human motion monitoring and human -computer interaction.