A temporary “living” tattoo that’s 3D printed has live ink made up of bacterial cells genetically programmed to light up when exposed to different types of stimuli.
This temporary tattoo as a living sensor. It could, for example, be designed to detect pollutants in the environment, sending its wearer a signal when they’re in the presence of dangerous toxins, said researchers at Massachusetts Institute of Technology (MIT).
Here’s how it works: First the bacterial cells end up programmed to respond to different compounds. Then those cells mix together with hydrogel and cell-feeding nutrients to form an ink.
Using a 3D printer, several layers of ink are printed onto a transparent patch to form a living, three-dimensional, interactive device — in this case in the shape of a tree. In this example, each branch of the tree consists of cells sensitive to a different substance. When the tattoo is put on the skin, those different regions will light up when exposed to the corresponding compound.
The researchers envision their creation as something that could be used to not just sense pollutants, but to detect changes in things such as temperature or pH level.
They also imagine it could end up used to manufacture things like drug capsules containing cells engineered to produce compounds like glucose which would be released therapeutically over time.
The researchers, led by Xuanhe Zhao, the Noyce Career Development Professor in MIT’s Department of Mechanical Engineering, and Timothy Lu, associate professor of biological engineering and of electrical engineering and computer science, said their technique can be used to fabricate “active” materials for wearable sensors and interactive displays. Such materials can be patterned with live cells engineered to sense environmental chemicals and pollutants as well as changes in pH and temperature.
Graduate student and team member Hyunwoo Yuk said in the future, researchers may use the team’s technique to print “living computers” — structures with multiple types of cells that communicate with each other, passing signals back and forth, much like transistors on a microchip.
“This is very future work,” Yuk said, “but we expect to be able to print living computational platforms that could be wearable.”