Researchers at Tsinghua University designed graphene-based e-tattoos that act as biosensors. The sensors can collect data related to the user's health, such as skin reactions to medication or to assess the degree of exposure to ultraviolet light.

The use of graphene aids the collection of electric signals and also imparts material properties to the sensors, allowing them to be bent, pressed, and twisted without any loss to sensors functionality. The new sensors have reportedly shown – via as series of tests – good sensitivity to external stimuli like strain, humidity, and temperature. The basis of the sensor is a material matrix composed of a graphene and silk fibroin combination.

The highly flexible e‐tattoos are manufactured by printing a suspension of graphene, calcium ions and silk fibroin. Through this process the graphene flakes distributed in the matrix form an electrically conductive path. The path is highly responsive to environmental changes and it can detect multi-stimuli.

The e‐tattoo is also said to be capable of self-healing. The tests reportedly showed how the tattoo heals after damage by water. This occurs due to the reformation of hydrogen and coordination bonds at the point of any fracture. The healing efficiency was demonstrated to be 100% and it takes place in less than one second.

The researchers believe that the e-tattoos can be used as electrocardiograms, for assessing breathing, and for monitoring temperature changes. This means that the e‐tattoo model could be the basis for a new generation of epidermal electronics.

Commenting on the research, chief scientist Yingying Zhang said: “Based on the superior capabilities of our e-tattoos, we believe that such skin-like devices hold great promise for manufacturing cost-effective artificial skins and wearable electronics.”



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