A team from the Massachusetts Institute of Technology have developed a gel that contains genetically programmed living cells, which means the "tattoo" can respond to various stimuli.
This new 3D printing technique was demonstrated using a tree-shaped "tattoo", which was patterned using live bacteria cells in the shape of a tree. Each cell is engineered to react to a different chemical so when this is done whilst the patch is on the skin, it responds accordingly.
Xuanhe Zhao, the Noyce Career Development Professor in MIT's Department of Mechanical Engineering, who led the project, said: "This hydrogel has ideal flow characteristics for printing through a nozzle. It's like squeezing out toothpaste. You need [the ink] to flow out of a nozzle like toothpaste, and it can maintain its shape after it's printed ... We found this new ink formula works very well and can print at a high resolution of about 30 micrometers per feature. That means each line we print contains only a few cells. We can also print relatively large-scale structures, measuring several centimetres."
And Timothy Lu, associate professor of biological engineering and of electrical engineering and computer science, believes this has a wider benefit too.
Lu explained: "We can use bacterial cells like workers in a 3D factory. They can be engineered to produce drugs within a 3D scaffold, and applications should not be confined to epidermal devices. As long as the fabrication method and approach are viable, applications such as implants and ingestibles should be possible."