I distinctly remember taking a test in fifth grade science class in which I had to name the states of matter. I would have risked my tiny fifth grade reputation on the fact that gas, liquid, and solid were the only possible answers. Luckily, science rarely stalls or advances as a result of elementary school unit tests and although I didn’t learn it until later, a fourth state of matter, plasma, was actually discovered in the middle of the 19th century by William Crookes.
If I had to hazard a guess as to why plasma was left off the list when I went to grade school, I would imagine it would be because it ruins the stove top matter transformation example where an ice cube is melted and then makes its final conversion into a gas. After all, in order to put a substance into this state it must be subjected to a strong electromagnetic field…something which is only rarely available to your average 11-year-old…hopefully…
In any case, plasma is a thing and it’s time we all get used to it because it is part of a pretty exciting set of developments in 3D printing. Namely, it is the state of the nanomaterials used in a new printing technique that allows for the deposition of those materials onto a flexible, 3D substrate.
As it turns out, the process by which nanoparticles can be printed in layers onto a substrate doesn’t require anything nearly as out of reach as one might at first imagine. In fact, inkjet printers are doing it all the time. Unfortunately, they are limited to printing onto rigid materials, require a liquid printing material, and can only print onto the surface of 2D objects. To overcome these limitations, researchers from NASA and the SLAC National Accelerator Laboratory have developed a process by which plasma can be printed onto flexible surfaces at a relatively low temperature. Not your typical elementary school science project.
For their first trick, the team printed directly onto paper using carbon nanotubes and helium-ion plasma pushed through a nozzle. One of the primary advantages of this new technique is the elimination of the need for heat treatment which kept things like printing on flammable materials such as paper or cloth out of the realm of possibilities. Mayya Meyyappan of NASA’s Ames Research Center explained the benefits of this new technique:
“You can use it to deposit things on paper, plastic, cotton, or any kind of textile. It’s idea for soft substrates…I can do things inkjet printing cannot do. But [it can also do] anything inkjet printing can do, it can be pretty competitive.”
This plasma printing technique is ideal for the creation of chemical and biological sensors with the addition of carefully selected molecules to the plasma ink, the sensors can be created to react to particular compounds such as ammonia gas or dopamine. It is also possible to use the technique to print things such as copper which would allow for batteries to be printed on thin sheets of aluminum.
More information and detailed descriptions are available in a paper — “Plasma jet printing for flexible substrates” — written by the research team and published in the journal Applied Physics. The paper’s authors included Ram P. Gandhiraman, Eric Singh, Diana C. Diaz-Cartagena, Dennis Nordlund, Jessica Koehne and M. Meyyappan. Tell us your thoughts on this new technology in the 3D Printed Substrates forum over at 3DPB.com.