Northwestern University Creates Optimal Vertical Electrochemical Transistor

Northwestern University researchers from multiple disciplines – including chemists, materials scientists, and biomedical engineers – have teamed up to create a transistor that is expected to be optimal for bioelectronics that need to be high-performance, lightweight, and flexible.

“This exciting new type of transistor allows us to speak the language of both biological systems, which often communicate via ionic signaling, and electronic systems, which communicate with electrons,” Jonathan Rivnay, professor of biomedical engineering at the McCormick School, said. “The ability of the transistors to work very efficiently as ‘mixed conductors’ makes them attractive for bioelectronic diagnostics and therapies.”

The vertical electrochemical transistor is based on a new kind of electronic polymer and a vertical, rather than planar, architecture. It conducts both electricity and ions, is stable in air, and is compatible with both blood and water. The new transistor has the ability to amplify significant signals, making it beneficial for biomedical sensing. It could be integral in developing wearable devices that could perform on-site signal processing directly at the biology-device interface. Potential uses include: monitoring heart rate and levels of sodium and potassium in the blood, as well as tracking eye movements to study sleep disorders.

“All modern electronics use transistors, which rapidly turn current on and off,” said Tobin J. Marks, a co-corresponding author of the study. “Here we use chemistry to enhance the switching. Our electrochemical transistor takes performance to a totally new level. You have all the properties of a conventional transistor but far higher transconductance (a measure of the amplification it can deliver), ultra-stable cycling of the switching properties, a small footprint that can enable high-density integration, and easy, low-cost fabrication.”