Ultra-Soft and Durable Skin Electronics for Next-Generation Wearable Devices

An important goal in biological monitoring is to acquire information about the state of a living body in a non-invasive, continuous, and precise manner, without interfering with its natural functions or activities. Because biological tissues are inherently soft and constantly in motion, sensors that make direct contact with them are inevitably exposed to physical disturbances. Researchers have made significant advances to reduce the negative effects associated with sensor attachment. For example, in temperature monitoring, lowering the heat capacity or thermal conductance of the sensor can help minimize the impact of heat transfer between the object and the sensor. Additionally, to address the differences in modulus between skin and electronics, flexible or stretchable sensors have been developed over the past decades.

In this talk, we will introduce ultra-soft and durable skin electronics designed to enhance biocompatibility through an extremely soft, thin, and porous nanomesh structure. These electronics can electrically functionalize the skin while preserving its natural functionalities. The nanomesh electrode with gas permeability, can adhere to the skin allows it to remain attached continuously for up to a week without causing skin inflammation. The nanomesh pressure sensor enables the monitoring of finger manipulation without interfering with the skin's natural sensations, although it is attached to the highly sensitive fingertip. Furthermore, the nanomesh strain sensor achieves both ultra-softness (with tensile stiffness lower than that of the skin layers) and mechanical durability against friction. Finally, we demonstrate the monitoring of skin deformation under mechanically harsh conditions, such as when the fingertip comes into contact with a ball during a pitching motion.