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Could nanoprinting kick-start a world of versatile home manufacturing?(Guardian Web Via Acquire Media NewsEdge) Printing foldable mobile phones on a sheet of paper from a normal 2D printer is just a decade away, according to Jürgen Steimle, head of the Embodied Interaction Group at the Max Planck Institute for Informatics in Saarbrücken, Germany. Steimle and his colleagues took a step towards this in 2013, when they used a standard printer loaded with nanoparticle ink to print a paper circuit that works even after the sheet is torn. In the past couple of years, similar applications have popped up in laboratories around the world. "People are starting to realise the power of printing," says Vincent Rotello, a chemist at the University of Massachusetts Amherst, who is working on a printable test strip for pathogenic bacteria in water. The convergence of nano and printing is partially due to the success of one eye-grabbing device, the 3D printer, which produces objects to a three-dimensional template by extruding soft plastic noodles that rapidly consolidate into the shape of the desired object. Scientists are now adding nanoparticles to the plastic, thereby giving these products "smart" properties, but the humble 2D printer, which is far more commonplace, is being revitalised by nanoparticle ink. Steimle's sensor, for example, needs only a normal inkjet printer, commercial photo paper, and a silver nanoparticles suspension that can be bought online. With these ingredients, Steimle and colleagues can lay a circuit on the paper that works like a touch sensor. When that's linked up to a computer, software can recognise which areas of the paper are being touched by the fingers of a user. It's not just simple and effective to set up – it's cheap too. "The ink needed to cover a sheet of A4 costs only one dollar, but about 20 cents is enough for a functional circuit", says Steimle. Additionally, the active parts of the circuits are arranged in the shape of a tree or star, so that if a portion of the paper is cut away, the remainder still works. "In such a way, the sensor could be cut and adapted to cover surfaces or fold objects without losing its function: we are in conversation with a car company that's interested in it," says Steimle. Steimle, who is working on an improved prototype that senses proximity, strength and deformation, envisions that this class of sensors could be used in roll-out tablets (made of a flexible structure that can be rolled and unrolled), smart wallpapers that interact as people touch them, or even body enhancers, like small screens on people's fingernails to display the face of a friend during a Voice-on-IP call, or email alerts. Health applications The printable test strip developed by Vincent Rotello last year makes use of similar hardware. He uses an Epson 50 device designed to print on CDs, standard paper, and some synthetic catalytic nanoparticles whose precise nature he wants to keep confidential. "The printer costs about $150 and can produce hundreds of strips in minutes, at a cost of a few tens of pence per strip," says Rotello. The test strips give a visual signal to the user when put in a sample of water with bacteria in it. The project is carried out in collaboration with scientists in Pakistan, who will test the strips in Lahore, the largest city in the Punjab region, where drinking water is often polluted by disease-causing bacteria. "The printer is cheap and can handle picolitre measurements of ink, and we can send templates worldwide to produce the strips locally," says Rotello. Another advantage is that the printer has 4 channels with 256 shades of colour. By modifying the nature of nanoparticles and substrates that are sent through these channels, one can explore an almost infinite set of ink compositions. "Scientists in Pakistan will have the possibility to adapt the prototype to their environment: printers enable us to crowdsource nanomanufacturing", says Rotello. Even more complex products can be built when nanoparticles are used in 3D printers. In 2013, a team based at Harvard University and the University of Illinois at Champaign-Urbana was able to print microscopic lithium-ion batteries from a 3D printer. The 3D printer enables tiny electrodes, thinner than a human hair, to be tightly interlaced, thereby obtaining more energy in less space. Given that the miniaturisation of medical implants or cameras is often curbed by the size of power devices, the potential unlocked by these batteries is huge. Rotello thinks the interface between nano and printing is much more than a temporary trend, and will yeild many surprises. "It could help to bridge the long-standing gap between nanotechnology in the lab and real-world nanomanufacturing," he says. (c) 2014 Guardian Newspapers Limited. |