Printed 2D materials make high-quality electrodes

Using ink made of 2D materials called MXenes, researchers have made soft electrode arrays that can be used on the skin or implanted in the body (Sci. Transl. Med. 2021, DOI: 10.1126/scitranslmed.abf8629). Compared to the metal electrodes used today, they give better quality signals without the need for sticky conductive gels.

The electrodes can be printed at low cost and could be customized for individual patients, says Flavia Vitale, a chemical engineer and neurologist at the University of Pennsylvania.

MXenes, a family of 2D transition metal carbides and nitrides, are highly conductive. Vitale and her colleagues etched electrode array patterns into a cellulose-polymer substrate, infused it with a water-based Ti₃C₂ MXene ink, and coated the device with an insulating polymer.

They used electrode arrays to record electrical activity of the hearts and brains of volunteers through the skin. The MXene electrodes produced signals with a higher signal-to-noise ratio than commercial silver-based electrodes, Vitale says. They also placed the electrode array directly on the brains of an anesthetized pig and rat to detect brain signals.

The new electrodes do not interact with the magnetic fields needed for imaging technologies such as CT scans and MRI. Tests on tissue-mimicking materials showed that while metallic electrodes produced tiny glitches in the images, MXene electrodes did not.