Soft Memory Device May Lead to Biocompatible Electronics

 Researchers at North Carolina State University (NC State; Raleigh) have created a soft memory device that thrives in wet environments and could someday lead to new biocompatible electronics.

“We’ve made a memory device completely out of soft materials, gels that are literally like Jell-O,” says Michael Dickey, assistant professor of chemical and biomolecular engineering at NC State and coauthor of a study on the devices.

The development came as the result of around two years of research. Dickey’s team, which had been studying a liquid metal alloy of gallium and indium, collaborated with a team working under Orlin Velev, Invista professor in the NC State department of chemical and biomolecular engineering. Velev’s team had been developing solar cells and diodes made from water-based gels.

“They were doing all this, but they were connecting them to the real world using rigid electrodes,” Dickey says. “They were taking something that was really soft and making it not so soft. Our group was studying liquid metal, whose properties allow it to be molded into shapes other than spheres…We thought if you put those two things together, you could make something entirely soft.”

The so-called mushy memory device creates the 0s and 1s of binary language using ions. The liquid metal alloy serves as an electrode. Positive and negative charges impact the thickness of an oxide layer, creating restive or conductive states accordingly.

“We’re using materials that, in principle, could interface with things you find in biology—cells, enzymes, maybe even tissue,” Dickey says.

The memory device they created is both pliable and able to function in environments where conventional electronics could not. For instance, Dickey says student researchers working on the project even brought the device to one of their meetings in a bucket of water.

“Anyone who has worked on electronics knows that no one in their right mind would ever put a transistor or a cell phone or computer in water,” Dickey says.

The researchers’ long-term goals include possibilities such as integrating biological species into the gels and using them as sensors.

“The thing that would be easiest to imagine but hardest to pull off is using [the soft memory device] to interface with neurons in the brain,” Dickey says. “But we have a long way to go before doing that.”