Researchers from University of California San Diego and University of Toronto have developed a way to apply ion-selective electrodes (ISE) using temporary tattoo technology. The method will allow for easy continuous measurement of the pH levels on the skin’s surface, an indicator of how much sweat is being secreted by the body. This has a variety of uses, from fine-tuning athletic training to diagnosing metabolic disorders.
Previous ISE’s weren’t very good at keeping contact with the skin for extended periods of time when sweat forms under the electrodes, so the use of temporary skin tattoos as an old method for a new trick solves the problem at minimum cost.
The new tattoo-based sensor stayed in place during tests, and continued to work even when the people wearing them were exercising and sweating extensively. The tattoos were applied in a similar way to regular transfer tattoos, right down to using a paper towel soaked in warm water to remove the base paper.
To make the sensors, [Vinci Hung, a PhD candidate in the Department of Physical & Environmental Sciences at UTSC] and her colleagues used a standard screen printer to lay down consecutive layers of silver, carbon fiber-modified carbon and insulator inks, followed by electropolymerization of aniline to complete the sensing surface.
By using different sensing materials, the tattoos can also be modified to detect other components of sweat, such as sodium, potassium or magnesium, all of which are of potential interest to researchers in medicine and cosmetology.
University of Toronto press release: Happy face tattoo does serious work
Study in journal Analyst: Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring