Yanliang Zhang, associate professor of aerospace and mechanical engineering at Notre Dame, and doctoral student Yipu Du developed the self-powered wearable device. (Credit: Notre Dame)

Wearable devices have traditionally needed an external power source and require exacting manufacturing processes. Now, researchers have developed an all-printed piezoelectric (self-powered) wearable device.

The researchers have created an innovative hybrid printing method — combining multi-material aerosol jet printing and extrusion printing — that integrates both functional and structural materials into a single streamlined printing platform.

Using their new hybrid printing process, the team demonstrated stretchable piezoelectric sensors, conformable to human skin, with integrated tellurium nanowire piezoelectric materials, silver nanowire electrodes and silicone films. The devices printed by the team were then attached to a human wrist, accurately detecting hand gestures, and to an individual’s neck, detecting the individual’s heartbeat. Neither device used an external power source.

Vital to the design are nanostructured materials with piezoelectric properties, which eliminate the need for poling or sintering, and the highly stretchable silver nanowire electrodes, which are important for wearable devices attached to bodies in motion.