China’s Tsinghua University Designs Multilayer Graphene Epidermal Electronic Skin

A scientist from China’s Tsinghua University has developed a graphene tattoo-like electronic skin that could be used as biological sensor for medical applications.

Electronic skin is an important biomedical sensor that is flexible and stretchable, with high sensitivity and comfort. It can sense body conditions such as pressure, temperature and heart beat. Due to graphene’s flexibility and conductivity, it is an ideal material for electronic skin.

A team led by Prof. Ren Tianling, a vice director at the sensor technology of environment and health center at Tsinghua University, has published an essay about the electronic skin on American scientific journal American Chemical Society·Nano, according to the university’s announcement on its website on July 31.

The team combined laser-reduced graphene with tattoo to mimic the function of electronic skin. Small changes of skin surface can be monitored by changes in electrical resistance. The team also initiated a new method of separating oxides from graphene to makes the device more sensitive and more resistant to higher temperatures.

In a process aided by water, the electronic skin can be transferred to human bodies as wearables. It can be attached on mask, wrists, throats and other body parts to detect voice, breathing and other body conditions. As laser light is programmable, tattoo on graphene can be personalized and redesigned.

Electronic skin is an important biomedical sensor that requires good flexibility and scalability, high sensitivity, good fit and comfort. "Graphene is an ideal material for electronic skin due to its excellent electrical conductivity and flexibility. However, how to make graphene more comfortable, beautiful, stable and reliable on the skin surface is an issue that needs to be solved," Ren Tianling explained.

Through the analysis and research on the microstructure of laser direct writing graphene, Professor Ren Tianling established a theoretical model of cracks based on graphene band structure, which better simulates the change process of resistance caused by stress.

"Multilayer graphene epidermis electronic skin can monitor the microscopic deformation of the skin surface through resistance changes, and measure the physiological signs of breathing, heartbeat, speech, etc. by attaching to various positions such as masks, wrists, and throats," Ren Tianling said.

In addition, during the device development process, the team created a new process for wet stripping of graphene oxide that leaves only graphene; making the device aesthetically more pleasing, more sensitive, and able to withstand higher temperatures.

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