Yale engineers open new field of inquiry in bioelectronics

A device created by Yale University engineers could open a new field of inquiry in bioelectronics, or the merging of biological and electronic systems.

The device, a nanoscale fluidic diode, can tightly control the flow of ions in fluids, such as sodium in water. It could serve as a building block for large-scale circuits that manage the flow and concentration of ions and molecules in electrolyte solutions, much as biological systems do naturally. These circuits could be useful for future desalination or fluid purification systems, among other applications.

Ions are atoms or groups of atoms that carry an electric charge. Examples include sodium, potassium, calcium and other electrolytes essential for healthy human life.

"Ultimately, this is giving us the tools to do real electronic-biological interfaces," said Mark Reed, professor of electrical engineering and applied physics and the principal investigator of the research team that produced the diode. The team, led by graduate student Weihua Guan, recently published its findings in the online journal Nature Communications.

The team's diode is analogous to solid-state semiconductor diodes commonly found in consumer electronics. Unlike an electrical diode, which channels electrons in a fixed manner, Guan's device can alter the concentration and direction of ion flows. It is also the first nanofluidic diode that allows a reconfiguration of the diode's function after it's already in place.

"We can create some things here that you can't do with an electrical device," Reed said. "In the fluidic diodes, we can actually tune that flow over a wide range. It gives us an extra degree of freedom that we don't have in electronic systems. In a way, it's the beginning of a transistor-like function."