Advances in mechanically active materials for soft wearable electronics

Soft wearable electronics provide a seamless interface between the human body and electronic systems to support real-time, continuous, long-term monitoring in healthcare and other applications. Incorporating mechanically active materials to these soft electronic systems can further expand sensing modalities, enhance sensing performances, and/or enable new functions that are challenging to achieve with physically static electronic devices. A key property of such mechanically active materials is that their shapes can change upon various external stimuli. This review highlights recent advances in this type of material, with a focus on discussing their integration with soft wearable devices and the resulting impact on the performances. Specifically, the content ranges from piezoelectric materials that generate ultrasound and surface acoustic waves, to magnetic materials that allow for new sensing modalities and haptic feedback, and to elastomeric materials that facilitate pneumatic and hydraulic actuation-all designed for soft wearable devices. The review concludes with an analysis of the key challenges and future opportunities for mechanically active materials.