3-D Printing a Living Tattoo

New technique 3-D prints programmed cells into living devices for the first time.


Using 3D printing, various scientists have already explored a variety of responsive materials. One of its example includes an ink made from temperature-sensitive polymers to print heat-responsive shape-shifting objects. This time, MIT scientists have come up with a new kind of ink made from genetically programmed living cells.

Scientists realized that live cells may likewise fill in as responsive materials for 3D-printed inks, especially as they can be hereditarily built to react to an assortment of jolts. Thus, they engineered the cells to light up in response to a variety of stimuli.

3-D Printing a Living Tattoo
MIT engineers have devised a 3-D printing technique that uses a new kind of ink made from genetically programmed living cells.
Courtesy of the researchers

For this, they mixed with a slurry of hydrogel and nutrients and printed the cells level wise. Doing so, the cells can be printed, layer by layer, to form three-dimensional, interactive structures and devices.

Following the technique, scientists printed a living tattoo- a thin, transparent patch patterned with live bacteria cells in the shape of a tree. The branches of this tree are fixed with cells touchy to an alternate concoction or sub-atomic compound. At the point when the fix is clung to skin that has been presented to similar mixes, comparing locales of the tree illuminate accordingly.

Scientists noted, “The 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.”

Moreover, scientists developed a model that predicts the interactions between cells within a given 3-D-printed structure. This mimics as a guide that tells how to design the responsive living materials.

Scientists particularly identified a hardier cell type in bacteria. The bacterial cells have extreme cell dividers that can survive moderately unforgiving conditions, for example, the powers connected to ink as it is pushed through a printer’s spout. Additionally, the bacteria are compatible with most hydrogels — gel-like materials that are made from a mix of mostly water and a bit of polymer. These hydrogels are capable enough to provide an aqueous environment that can support living bacteria.

Scientists tested the type of hydrogels via a screening test that would best host bacterial cells. They found that the hydrogels with pluronic acid are the most compatible.

Zhao 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.”

By using a composition of bacteria, hydrogel, and nutrients to sustain the cells, scientists have created a recipe for their 3-D ink.

They printed the ink using a custom 3-D printer that they built using standard elements combined with fixtures they machined themselves. To demonstrate the technique, the team printed a pattern of hydrogel with cells in the shape of a tree on an elastomer layer. After printing, they solidified or cured, the patch by exposing it to ultraviolet radiation. They then adhere the transparent elastomer layer with the living patterns on it, to the skin.

The scientists likewise designed microbes to speak with each other. They customized a few cells to illuminate just when they get a specific flag from another cell. To test this sort of correspondence in a 3-D structure, they printed a thin sheet of hydrogel fibers with “input,” or flag creating microbes and chemicals, overlaid with another layer of fibers of an “output,” or flag accepting microscopic organisms. They found these output fibers lit up just when they covered and got input signals from relating microbes.

Zhao said, “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 centimeters.”

Timothy Lu, associate professor of biological engineering said, “We can use bacterial cells like workers in a 3-D factory. 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.”