Painted, no longer placed: they create ink that works as a more sensitive and precise electrode

This new type of electrodes that spread like a painting is described in a study led by Pennsylvania State University (USA) and published by PNAS.

Wearable electrodes can allow continuous monitoring and provide electrophysiological data. Traditional designs use rigid metal-based materials that offer stability, but who have difficulty staying attached to the body during movement or exercise.

Other experimental designs use hydrogel, which can absorb water and swell to better adapt to body movements; However, over time they can dehydrate, causing the electrodes to lose adhesion and elasticity with prolonged use.

The new electrodes in paint demonstrated high connectivity with the skin and low impedance (loss of contact) in tests carried out with people.

The paint uses PEDOT:PSS ink (a type of polymer) as a conductive material and adapts to the contours of the skin to achieve high skin connectivity.

The ink has the consistency of glue when wet and behaves similar to face paint. Applied to the skin, it dries in less than 10 minutes, when it already acts as a functional electrode. Additionally, it can be removed with water or reapplied if necessary.

At first, it is almost transparent, but you can use food coloring to give it all the shades and apply it with a brush making any design or drawing.

Tests showed how the electrode could be used for wireless monitoring of electrocardiograms, measuring muscle activity for gesture recognition and robotic control, and monitoring electroencephalograms through hair.

To improve the stability between the electrodes and the sensors to which they transmit information, an electrode connection area is applied to a porous silver fabric, almost like a metallic fabric, which is placed on the skin.

The connection portion is then attached to a port on the larger electrical module, which is taped to the user’s skin under clothing and wirelessly transmits electrical signals to a computer.

The team plans to continue developing its electrodes to be able to carry out, in the future, more advanced monitoring of biomarkers such as cortisol or glucose.