New method can deposit nanomaterials onto flexible surfaces and 3-D objects
Printing has come a long way since the days of Johannes Gutenberg. Now, researchers have developed a new method that uses plasma to print nanomaterials onto a 3-D object or flexible surface, such as paper or cloth. The technique could make it easier and cheaper to build devices like wearable chemical and biological sensors, flexible memory devices and batteries, and integrated circuits.
One of the most common methods to deposit nanomaterials–such as a layer of nanoparticles or nanotubes–onto a surface is with an inkjet printer similar to an ordinary printer found in an office. Although they use well-established technology and are relatively cheap, inkjet printers have limitations. They can’t print on textiles or other flexible materials, let alone 3-D objects. They also must print liquid ink, and not all materials are easily made into a liquid.
Some nanomaterials can be printed using aerosol printing techniques. But the material must be heated several hundreds of degrees to consolidate into a thin and smooth film. The extra step is impossible for printing on cloth or other materials that can burn, and means higher cost for the materials that can take the heat.
The plasma method skips this heating step and works at temperatures not much warmer than 40 degrees Celsius. “You can use it to deposit things on paper, plastic, cotton, or any kind of textile,” said Meyya Meyyappan of NASA Ames Research Center. “It’s ideal for soft substrates.” It also doesn’t require the printing material to be liquid.
The researchers, from NASA Ames and SLAC National Accelerator Laboratory, describe their work in Applied Physics Letters, from AIP Publishing>.
They demonstrated their technique by printing a layer of carbon nanotubes on paper. They mixed the nanotubes into a plasma of helium ions, which they then blasted through a nozzle and onto paper. The plasma focuses the nanoparticles onto the paper surface, forming a consolidated layer without any need for additional heating.
The team printed two simple chemical and biological sensors. The presence of certain molecules can change the electrical resistance of the carbon nanotubes. By measuring this change, the device can identify and determine the concentration of the molecule. The researchers made a chemical sensor that detects ammonia gas and a biological sensor that detects dopamine, a molecule linked to disorders like Parkinson’s disease and epilepsy.
But these were just simple proofs-of-principle, Meyyappan said. “There’s a wide range of biosensing applications.” For example, you can make sensors that monitor health biomarkers like cholesterol, or food-borne pathogens like E. coli and Salmonella.
Because the method uses a simple nozzle, it’s versatile and can be easily scaled up. For example, a system could have many nozzles like a showerhead, allowing it to print on large areas. Or, the nozzle could act like a hose, free to spray nanomaterials on the surfaces of 3-D objects.
“It can do things inkjet printing cannot do,” Meyyappan said. “But anything inkjet printing can do, it can be pretty competitive.”
The method is ready for commercialization, Meyyappan said, and should be relatively inexpensive and straightforward to develop. Right now, the researchers are designing the technique to print other kinds of materials such as copper. They can then print materials used for batteries onto thin sheets of metal such as aluminum. The sheet can then be rolled into tiny batteries for cellphones or other devices.
Learn more: Printing nanomaterials with plasma
Berkeley Lab Scientists Believe Biomanufacturing a Key to Long-term Manned Space Missions
Does synthetic biology hold the key to manned space exploration of the Moon and Mars? Berkeley Lab researchers have used synthetic biology to produce an inexpensive and reliable microbial-based alternative to the world’s most effective anti-malaria drug, and to develop clean, green and sustainable alternatives to gasoline, diesel and jet fuels. In the future, synthetic biology could also be used to make manned space missions more practical.
“Not only does synthetic biology promise to make the travel to extraterrestrial locations more practical and bearable, it could also be transformative once explorers arrive at their destination,” says Adam Arkin, director of Berkeley Lab’s Physical Biosciences Division (PBD) and a leading authority on synthetic and systems biology.
“During flight, the ability to augment fuel and other energy needs, to provide small amounts of needed materials, plus renewable, nutritional and taste-engineered food, and drugs-on-demand can save costs and increase astronaut health and welfare,” Arkin says. “At an extraterrestrial base, synthetic biology could make even more effective use of the catalytic activities of diverse organisms.”
Arkin is the senior author of a paper in the Journal of the Royal Society Interface that reports on a techno-economic analysis demonstrating “the significant utility of deploying non-traditional biological techniques to harness available volatiles and waste resources on manned long-duration space missions.” The paper is titled “Towards Synthetic Biological Approaches to Resource Utilization on Space Missions.” The lead and corresponding author is Amor Menezes, a postdoctoral scholar in Arkin’s research group at the University of California (UC) Berkeley. Other co-authors are John Cumbers and John Hogan with the NASA Ames Research Center.
One of the biggest challenges to manned space missions is the expense. The NASA rule-of-thumb is that every unit mass of payload launched requires the support of an additional 99 units of mass, with “support” encompassing everything from fuel to oxygen to food and medicine for the astronauts, etc. Most of the current technologies now deployed or under development for providing this support are abiotic, meaning non-biological. Arkin, Menezes and their collaborators have shown that providing this support with technologies based on existing biological processes is a more than viable alternative.