Self-powered e-skin enables monitoring of subtle human activities

by Xinhua writers Hu Tao, Zhang Wenjing

LANZHOU -- A team of Chinese researchers have recently developed a new type of self-powered flexible and transparent electronic skin (e-skin) that can monitor subtle human activities, shedding light on the future of wearable electronics.

This new e-skin integrates a flexible transparent supercapacitor as an energy storage device with a stretchable transparent strain sensor, said Lan Wei, professor at the School of Physical Science and Technology of Lanzhou University and leader of the research team.

"Thanks to its mechanical softness, the integrated e-skin can be directly attached to various locations on the body for the monitoring of human activities," Lan added.

It has great application prospects in smart health care, human-machine interaction, virtual reality and artificial intelligence, among other fields.

As the largest organ of the human body, the skin is responsible for multiple major functions such as protection, respiration, perspiration, thermo regulation, and sensory stimulation. It forms the basis of people's physical interactions with the outside world.

The ideal e-skin should be ultra-sensitive, self-powered, conformal to human skin, and optically transparent for visual or aesthetic purposes.

"Inspired by sensory functions and performance of real human skin, we have been devoted to making the new e-skin both flexible and transparent to meet aesthetic as well as functional requirements," Lan said.

The all-in-one system of the new e-skin is composed of a transparent supercapacitor, stretchable strain sensors and snakelike electrical resistance.

The assembled flexible and transparent supercapacitor uses oxygen-deficient molybdenum oxide nanowires and cellulose nanofiber composite as paper electrodes, achieving an excellent combination of high transparency and outstanding energy-storage capacity to drive the operation of the sensor.

Tests have shown that the new e-skin has an excellent performance in terms of its flexibility, transparency, electrochemistry and high sensitivity.

After charging, it is capable to simulate the perceptive function of real skin. It can be applied to human skin to realize real-time monitoring of people's subtle physical signals and multi-scaled activities, such as pulse, swallowing and body movements.

"E-skin is the core of future wearable electronic devices with promising prospects. For example, it may help surgeons in more precisely controlling surgical robots, enable long-distance 'touches' between close people, and create a more immersive gaming experience," Lan said.

Going ahead, the research team will focus on strengthening the sensory capacity and power supply of the e-skin, making it even closer to human skin and more adaptive to various future applications, Lan added.