Researchers at King Abdullah University of Science and Technology of Saudi Arabia has found that a material that mimics human skin in strength, stretchability and sensitivity could be used to collect real-time biological data.
Most e-skins are developed on a stretchy surface which attaches to human skin by layering an active nanomaterial (the sensor). Even though, the link between these layers are usually too vulnerable, which decreases the material’s resilience and sensitivity, alternatively, if it is too solid the flexibility becomes reduced, making it more likely that the circuit will crack and break.
“The ideal e-skin will mimic the many natural functions of human skin, such as sensing temperature and touch, accurately and in real-time. However, making suitably flexible electronics that can perform such delicate tasks while also enduring the bumps and scrapes of everyday life is challenging, and each material involved must be carefully engineered. The landscape of skin electronics keeps shifting at a spectacular pace. The emergence of 2D sensors has accelerated efforts to integrate these atomically thin, mechanically strong materials into functional, durable artificial skins.”
A group led by Cai and colleague Jie Shen from KAUST has now developed a robust e-skin using a hydrogel strengthened with silica nanoparticles as a solid and elastic substrate and a 2D titanium carbide MXene as the sensing sheet, secured together with highly conductive nanowires.
Mr. Shen added, “Hydrogels are more than 70 percent water, making them very compatible with human skin tissues. By pre-stretching the hydrogel in all directions, applying a layer of nanowires, and then carefully controlling its release, the researchers created conductive pathways to the sensor layer that remained intact even when the material was stretched to 28 times its original size.”
The developed prototype e-skin can recognize objects at a range of 20 cm, react to stimuli of less than one-tenth of a second. And also it could discern handwriting written on it when used as a pressure sensor. It continued to function well after 5,000 deformations, each time improving in about a quarter of a second. “It is a striking achievement for an e-skin to maintain toughness after repeated use,” says Mr. Shen, “which mimics the elasticity and rapid recovery of human skin.”
A variety of biological details, such as changes in blood pressure that can be detected from vibrations in the arteries to movements of large limbs and joints could be monitored by e-skins. It is then possible to share and store this information via Wi-Fi on the cloud.
Vincent Tung, Group Leader said, “One remaining obstacle to the widespread use of e-skins lies in scaling up of high-resolution sensors. However, laser-assisted additive manufacturing offers new promise.”
“We envisage a future for this technology beyond biology. Stretchable sensor tape could one day monitor the structural health of inanimate objects, such as furniture and aircraft,” added Ms. Cai.
KAUST intends to become a destination for scientific and technical education and research. It allows university members to fulfill their intellectual potential in a state-of-the-art environment.