Researchers develop electronic tattoos to measure sweating.

A research team at the University of Massachusetts Amherst is developing graphene electronic tattoos that adhere to the skin and function as biosensors. These devices are capable of analyzing compounds present in sweat, which could enable the detection of various health conditions and stress levels.

These wearable sensors, initially conceived by specialists at Northwestern University, are less than a millimeter thick, making them virtually invisible and able to adapt to the movement of the skin. It is expected that in the future, these patches will be used for real-time and continuous readings.

So far, the research has focused on how to use these biosensors to monitor vital parameters such as heart rate and blood pressure, two key indicators of possible health complications. However, the next generation of these patches is anticipated to obtain data from sweat, an approach that has generated significant interest in the scientific community.

In 2017, researchers at the University of Texas developed an even thinner version of a graphene biosensor that was applied to the skin in a manner similar to a temporary tattoo. Now, the team at the University of Massachusetts Amherst aims to explore the properties of sweat through these novel e-tattoos.

Dmitry Kireev, a member of the team, notes that sweat transports various compounds from inside the body to the surface of the skin, and their initial goal is to measure cortisol, which acts as an indicator of stress and other disorders. While sweat monitoring is not a novel idea, many laboratories are creating patches that detect chemical compounds, often using electrochemical sensors that require chambers to collect sweat, which limits their size and versatility.

The innovation of graphene e-tattoos lies in their ability to function without these chambers, making them more compact devices. Essentially, graphene acts as a transistor; when a compound present in sweat interacts with the molecules on the surface of graphene, an electric signal is generated that allows for the measurement of the compound's concentration through variations in the transistor's resistance.

In the future, these e-tattoos are expected to detect other compounds in sweat such as glucose, lactate, and estrogen, which could serve as indicators of health problems. As lifestyle accessories, these devices could provide early signals of certain conditions or serve as an additional source of valuable information for fitness applications. In a medical setting, biosensors would enable the transmission of real-time data without the need for blood analysis.

However, the implementation of this technology is still underway. Currently, graphene e-tattoos require connection to an electronic circuit with a chip to transmit data, which prevents them from being as flexible and invisible as desired. Therefore, to achieve this goal, researchers will need to develop fully integrated circuits that use graphene and include power sources and wireless transmitters. This process may present significant challenges, but it is expected that in the next decade, sweat-detecting e-tattoos will be integrated into the most advanced smartwatches.