Bacteria are an important part of the world we live in. They can be dangerous or beneficial, and they are present in large numbers around us. Bacteria have a variety of applications, and an unusual one that was recently developed by MIT is the idea of Living Ink.
Behind the Living Ink
This new technology was recently created successfully by a team of engineers working at MIT. Live ink printed in 3D can react to specific chemicals with which it comes into contact when illuminated. Genetic engineering is the mechanism by which these engineers were able to create living and receptive cells in the form of ink.
According to MIT News, engineers used a mixture of water / polymer, nutrients and living cells to form an ink that can be formed into 3D structures using a 3D printer. The reason why the bacteria were chosen over other cells was due to their ability to recover in stressful situations. The fact that bacteria can survive when they are added to a hydrogel, and then deal with the intense force of being pushed through a small nozzle, suggests that these cells were definitely the right choice for the first viable form of living ink.  Regarding the conditions to which cells react, live ink can be preprogrammed to respond to a wide range of different chemicals. This reaction has a visible effect when the cells are illuminated. As proof and demonstration, MIT engineers printed a thin "tree", with each branch reacting to a different chemical.
Then, like a tattoo, the finished hydrogel patch was placed on the back of a hand that had covered in the reactive chemicals. The following image shows the result, with the live ink responding to the different chemical products through visual feedback.
Meaning and future study
This breakthrough in living ink technology builds a future in which tattoos can monitor different chemicals when used.
MIT researchers have stated that with further development, cells may communicate with each other. This would allow a basic 3D printed laptop that is receptive and alive. For now, however, the focus of this technology is to build live sensors that we can use as patches.
The practical applications of this living ink in its current form is to use it as a way to administer medications over time, or even to revolutionize the field of surgical implants.
While this technology is still in its infancy, the implications of a living ink are immense. The ability to design bacteria and make them survive through such a stressful process as 3D printing opens the door to all kinds of future technological development.
While at this time the ink simply responds to different chemicals, the fact that it is the basis for a kind of living computer means that this complexity and applications of this technology will only continue to grow. We will have to see what the future of living ink has in store.