Is 3D Printing living tattoos the future of electronics?

Wearable tech is the name given to smart electronic devices that can be worn or implanted in the body. An enticing opportunity for innovative tech developers in sports, health, fashion and entertainment, 3D printing is revealing new possibilities for wearable tech such as electronic second skins, and smart fabrics.

In the latest research from Massachusetts Institute of Technology (MIT), a team has developed a “living” 3D printer bio-ink that’s not only smart but could change the way we think about technology altogether. Harnessing natural reactions of bacteria, responsive devices made using this smart ink represent the basic build blocks of electricity-free wearable tech.

Made by members of the same team that made the soft-robotic, fish-catching glove, this 3D printable bio-ink adds to an extensive portfolio of smart materials in development at MIT.

3D printing and programming genetically engineered bacteria
This MIT materials study was led by Prof Xuanhe Zhao and Dr. Timothy Lu of the Soft Active Materials Laboratory. As a proof-of-concept, the researchers and their team demonstrate how live 3D printed bacteria bio-ink containing bacteria can be programmed to light up when it receives a particular chemical signal.

First, the ink is prepared with ingredients to make it the perfect microenvironment for living matter. To a hydrogel base, the researchers add a photo-initiator so the material can be cured, along with bacterial cell pellets, bacterial feed, and deionized water.

In preparation, it was also essential for the team to select the appropriate bacteria, as previous attempts using other cells had failed. “It turns out those cells were dying during the printing process because mammalian cells are basically lipid bilayer balloons,” explains Hyunwoo Yuk, one of the study’s co-authors, “they are too weak, and they easily rupture.” 

Bacterial cells were chosen because their protective cell walls can withstand the pressures of 3D printing and thrive inside aqueous hydrogels. The bacteria were biologically engineered to emit green fluorescent proteins (GFPs), either in their normal state or when activated by a particular chemical signal.


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