A stretchable transistor switches between logic and synapse with salt

A team at Pusan National University led by Hyunseok Shim built a fully stretchable organic electrochemical transistor that changes what kind of component it is according to the salt around it. The work appeared in ACS Nano on 24 June 2026; the university publicised it on 3 August.

The device is made from PEDOT:PSS, a conducting polymer, modified with two additives that raised its conductivity and let it stretch repeatedly without degrading. In a high sodium-chloride concentration it switches sharply enough to serve as digital logic, and the team implemented NAND, NOR and inverter gates with it. In a low concentration the same device stops switching cleanly and instead holds a graded, decaying state — the behaviour used to imitate a synapse. The film also shifts from light to dark blue as it moves between modes, so its operating state can be read by eye.

As a demonstration the team built a patch that takes skin temperature and swelling as logic inputs and tightens or loosens a compression band in response.

The claim is a materials one: a single soft component that both computes and remembers, where an implant or a skin patch would otherwise need separate circuits for each. This is a laboratory device, not a clinical product.

The paper is paywalled; the figures here come from the university’s own release and from the article’s registered metadata.