OECTs are designed to measure signals created by electrical impulses in the body, such as heartbeats or brainwaves. The current most sensitive OECTs use a material where only holes (p-type) are transported. Electron transport in these devices, however, has not been possible, since n-type materials readily break down in water-based environments like the human body.
Working on this issue, the team have demonstrated the first ambipolar OECT that can conduct electrons (n-type) as well as holes with high stability in water-based solutions.
The team overcame the instability of n-type materials in water by designing new structures that prevent electrons from engaging in side-reactions, which would otherwise degrade the device.
The devices are claimed to detect positively charged sodium and potassium ions, important for neuron activities in the body, particularly in the brain.
PhD student, Alexander Giovannitti, said: "Proving that an n-type OET can operate in water paves the way for new sensor electronics with improved sensitivity.
"It will also allow new applications, particularly in the sensing of biologically important positive ions, which are not feasible with current devices. For example, these materials might be able to detect abnormalities in sodium and potassium ion concentrations in the brain, responsible for neuron diseases such as epilepsy."
