Researchers at the University of Washington have developed a proton-based transistor that might eventually enable machines to communicate with living things and provide improved cybernetics and digital implants.
While devices, such as flashlights and iPads, transmit information using electrons, living things send signals using ions or protons. The Washington researchers have constructed a transistor that uses protons, a key development needed to build devices that can communicate directly with living things. The researchers’ study, "A Polysaccharide Bioprotonic Field-Effect Transistor," was recently published online in the journal Nature Communications.
The genesis of the research came four years ago when Marco Rolandi, an assistant professor of materials science and engineering at Washington, was applying for a faculty job and had to come up research proposals. "I have a background in nanofabrication and nanotube electronics, but I have always been fascinated by biolelectronics," Rolandi says.
Rolandi wanted to use biological molecules in transistors. "One day, I was in my small apartment with the floor covered with papers about DNA, proteins, and pretty much any piece of living tissue you could imagine," he says.
Rolandi was interested in keratin nanofibers as a support for poly anilines, which are good electronic conductors. "Then at one point I thought typically biological molecules—at least the ones that have not been tried in transistors yet—are not very good at conducting electrons," he says. "Then a paper I was reading mentioned the protonic conductivity of keratin. So I thought perhaps protons are the way to go."
The group of researchers did encounter some problems from the start. "Initially, nobody in the lab knew how to work with biological materials," Rolandi says. "We started with keratin and collagen, because the proton conductivity was already reported, but these turned out to be terrible choices for device integration. Dr. Chao Zhong [a postdoctoral associate in Rolandi’s group] had the idea to work with polysaccharides."
Perhaps the main challenge during the research, Rolandi says, "was to keep going when things were not working well. There was enough evidence that we were looking in the right direction," but Rolandi and the team had no existing guidelines to help them in the project.
Rolandi says the idea for the proton-based transistor is actually simple. If protons can move along a proton wire, he says, there is no fundamental reason why this current can’t be modulated by using an electric field. "The geometry is not particularly exotic," he says.
The next steps in the research are to try to fabricate a single nanofiber, nanoscale device, and begin interfacing living cells with the device to see whether the researchers can monitor the activity of proton selective ion channels.
Bob Violino is a freelance science and technology writer based in Massapequa Park, NY.