If you’ve ever had an electrocardiogram, you may have experienced the gel electrodes placed on various parts of your chest coming loose or getting pulled off. If it’s necessary to get another reading during the same doctor’s office or emergency room visit, a staff member usually has to re-attach some or all of the electrodes. Gel electrodes are the go-to standard for short-term electrical impulse monitoring, but they are not useful for long-term monitoring. Tattoo electrodes, however, may be the answer. We’ve written about temporary tattoos used to measure UV exposure, blood alcohol, and blood glucose, but never before for use as electrodes.

Researchers from Austria’s Institute of Solid State Physics at TU Graz and three Italian institutions developed technology to print tattoo electrodes suitable for long-term medical diagnostics. In a paper published in Advanced Science titled Ultraconformable Temporary Tattoo Electrodes for Electrophysiology, the team outlined its work with dry, unperceivable, temporary tattoo electrodes. The tattoos are printed by an inkjet printer using a conductive polymer. The process produces single or multielectrode arrays on standard commercial decal transfer paper. The tattoos are less than one micrometer thick which lets them act like the thin plastic wrap used in homes to cover food; the material adheres by fitting or “conforming” to the surface to which it is applied. Electrophysiological testing by the research team validated the very-long-term potential of the tattoos for electromyography (EMG) and electrocardiography recordings on various locations on limbs and face. The tattoo material also can be perforated and still work, making it suitable for areas with growing hair.

The TU Graz scientists are developing the technology further with plans for materials and patterns that will allow large-scale, low-cost production. According to Francesco Greco, a materials scientist at TU Graz, international biomedical companies have already expressed interest in participating in further development.