"Most of our technology relies on electronic currents, but biology transduces signals with ions," said Professor David Ginger. "If you want to interface electronics and biology, you need a material that communicates across those two realms."
To address this issue, the researchers measured a thin film made of a single type of conjugated polymer, the poly(3-hexylthiophene), or P3HT, as it interacted with ions and electrons.
They showed how variations in the polymer layout yielded rigid and non-rigid regions of the film, and that these regions could accommodate electrons or ions – but not both equally.
The softer, non-rigid areas were poor electron conductors but could swell to take in ions, while the opposite was true for rigid regions.
"This was an almost imperceptible swelling – just 1% of the film's total thickness," said research scientist Rajiv Giridharagopal. "And using other methods, we discovered that the regions of the film that could swell to accommodate ion entry also had a less rigid structure and polymer arrangement."
These results demonstrate how critical the polymer synthesis and structure is to the film's electronic and ionic conductance properties. According to the researchers, the findings may point the way forward in creating polymer devices that can balance the demands of electronic transport and ion transport.
"We now understand the design principles to make polymers that can transport both ions and electrons more effectively," said Ginger.
According to the team, an organic polymer that can accommodate both types of conduction is the key to creating new biosensors, flexible bioelectronic implants and better batteries.
