Boise State University researchers announced on Mar. 11 the development of a new type of removable electronic tattoo, or “E-tattoo,” designed for use in wearable technology. The research team, led by doctoral student Ajay Pratap and Professor David Estrada, created these ultra-thin, flexible devices that can be applied directly to the skin and removed with rubbing alcohol.
The E-tattoo project is significant because it advances the field of wearable electronics by offering a device that not only monitors health signals but also harvests energy from human motion. This could lead to more sustainable and efficient wearable systems.
Pratap said, “E-tattoo is a fancy word for skin electronics, and we can cut them into any kind of designs we want. They directly go on the skin like a tattoo, but they are removable. Because they are functionalized material, they can do a lot of things; for example, energy harvesting or sensing, electrocardiogram monitoring, and monitoring muscle activity through electromyography.”
The research team demonstrated that their E-tattoos could capture electrocardiogram (ECG) and electromyography (EMG) signals while remaining flexible and adhering to the skin during movement. Outfitted with nano-scale generators, these devices can collect energy generated from daily activities such as walking—potentially one to two kilojoules per day—to power low-energy electronics like sensors or smartwatches. “According to research and available data, the average human walks 5,000 to 10,000 steps per day, and that generates one to two kilojoules of energy,” Pratap said. “So our target is to harvest that energy for the low-powered electronics: for example, LED sensors, your heart sensors or your smartwatch.”
The E-tattoos are made using a novel polymer spun into fibers and coated with titanium carbide MXenes—a material known for its suitability in energy harvesting applications. Estrada explained the process: “The electrospinner is used to create nanofiber mats, which form the foundation of the E-tattoo… It basically uses a high electric field between a needle and the drum to pull the polymer into these nanoscale fibers while they fly towards the drum and are collected in random mat of fibers that look a bit like spaghetti on a plate.” He added that this new polymer may be more environmentally friendly than those typically used in similar technologies: “We’re one of the few groups in the world working with this polymer for this application… That’s one of the big advantages of Ajay’s research.”
Pratap credited his success to strong support from his interdisciplinary team: “I got help all the time,” he said. “I got help from Professor Estrada. I got help from my team – amazing. Whenever I had any questions… they always came up with some solution. That’s why I did not feel any kind of struggle in the whole project.”
The findings were published in Advanced Science journal by Pratap; Estrada; Fereshteh Rajabi Kouchi; Tony Valayil-Varghese; Hailey Burgoyne; Attila Rektor; Michael Curtis; Miranda Lea Nelson; Francis N. Mokogwu; Corey M. Efaw; Josh Eixenberger; Allyssa Bateman; Benjamin C. Johnson; Brian Jaques; Zhangxian Deng; Kurtis Cantley; and Christopher E. Shuck.
