In the near future, your local hardware store could include a “green electronics” counter where friendly clerks unspool sheets of plastic film and print devices while you wait.
Need a few more solar panels? No problem.
How about a flexible LED lighting strip? This roll over here.
Computer? Loudspeaker? Or maybe transparent, energy-producing panels for your greenhouse? On sale today!
Though the scene is hypothetical, the emerging technology for organic, thin-film polymer plastics is up and running in laboratories around the world, including those of the Collins Research Group at Washington State University.
Led by assistant professor of physics Brian Collins, the enthusiastic young team is part of an international effort to develop electronics composed of earth-abundant elements such as carbon, nitrogen, and oxygen. In contrast, today’s electronics are usually powered by silicon in combination with rare or toxic metals like silver, lead, mercury, and cadmium.
Collins says carbon-based polymer electronics offer clear advantages. For one, they are biodegradable and environmentally friendly. They are also compatible with human tissue and could potentially be used as brain implants for restoring movement to paralyzed limbs and vision for the blind.
Like plastic wrap, the polymers are flexible. And their properties are easily “tuned” or adjusted to meet the needs of various applications. They can also be made into inks for printing with inkjet or 3D printers. In fact, Collins foresees a day when an entire device could be printed at home—complete with battery, solar panel, and LED screen.
“It’s the technology of the future,” he says with a grin.
Indeed, the possibilities are limitless and all stem from the discovery of semiconducting polymers by a trio of Nobel-winning chemists in 2000. These plastic-like materials contain optical and electronic properties that are especially suited for transistors.
Collins describes transistors as small switches that are used to turn electrical signals off and on.
“Transistors allow you to use a tiny signal to control a huge machine,” he says. “They make computers possible. When you put in a request, billions of transistors coalesce to open logic gates, and then trigger memory, operations, and instructions. We need transistors to be able to control almost anything.”
In a recent study, Collins and research partners in France, Spain, and California created a bioelectronic “transistor” that mimics nerve function. The device could eventually be developed into a nerve bypass system, say for a spinal injury where the brain’s impulses are blocked from reaching target muscles.
Through a brain implant, the device would allow a computer to “read” a patient’s desire to move and send electrical signals directly to his hand or foot, bypassing the damaged nerves.
The technology could eventually lead to thought-controlled prostheses, as recently demonstrated in an Ohio man. Scientists at the Feinstein Institute for Medical Research in New York used an inorganic brain implant and bulky equipment to enable him to move his fingers after five years of paralysis.
Collins says organic polymers offer a more sensitive and biocompatible option—and could be made into small, permanent implants complete with computer and components.
Though organic electronics offer extraordinary potential, their commercial success will depend in part on the efforts of Collins’ research team. While chemists design and fabricate the polymers, it’s the physicists who help ensure they function well on the molecular level.
It turns out that polymers which seem so promising in the liquid form often perform poorly once printed and dried. For years, the enigma puzzled the scientists.
It was Collins’ team who recently spotlighted the problem. Using a billion-dollar X-ray machine called a synchrotron, located at Berkeley National Laboratory, they found that polymer nanoparticles change configuration as they go from a liquid to solid state. It’s similar to the way water molecules change their arrangement to form ice.
The discovery came through Collins’ innovative development of X-ray techniques that can isolate and identify individual molecules. He is now able to view and measure polymer nanostructure in a way never before possible. Once problems are identified, he tweaks or “tunes” the nanostructure to work more effectively.
So far, he has used the procedure to improve solar cells, organic LEDs, and a variety of transistors, including the new bioelectronic device.