Engineers at MIT have manufactured a 3D printing machine that creates a ‘living tattoo’ – the ink is made from “genetically programmed living cells”.

The first piece printed is a tree tattoo, made with living bacteria – each individual branch has a different kind of molecular and cell that reacts differently. When applied to the skin, the tree “lights up” as the compounds react. Because the cells respond differently to stimulation, layers form three-dimensional and interactive pieces.

It’s applied directly to the skin with a printable hydrogel with the bacteria inside.

The research that went into the living tattoo has been published in the journal Advanced Materials, led by MIT’s department of mechanical engineering professor Xuanhe Zhao and biological engineering and electrical engineering and computer science professor Timothy Lu. 

As MIT reports, 3D-printed inks have been explored in other areas, like temperature-sensitive ‘polymers’ that work to create heat-responsive, shape-shifting devices, while others move in response to light and dark. 

Researchers assert that the technique they have engineered could later be used to print ‘living computers’, with cells that communicate and pass messages back and forth. They also see it being used to create types of surgical implants and drugs. 

“We can use bacterial cells like workers in a 3-D factory,” Liu says. “They can be engineered to produce drugs within a 3-D 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.”