Electrochemical logic circuits developed by Swedish team

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A team from Linköping University says it has developed the first complementary electrochemical logic circuits that can function stably for long periods in water. According to the researchers, this is a ‘significant’ breakthrough in the development of bioelectronics.

The first printable organic electrochemical transistors were presented by researchers at LiU as early as 2002, and research since then has progressed rapidly. Several organic electronic components, such as light-emitting diodes and electrochromic displays, are already commercially available.

The dominant material to date has been PEDOT:PSS; a p-type material in which the charge carriers are holes. In order to construct effective electronic components, the team required an n-type material. However, it was difficult to find a sufficiently stable polymer material that could operate in water media and sustain high currents when doped. Simone Fabiano, head of research in the University’s Organic Nanoelectronics group, has developed such an n-type conducting material.

Researcher Hengda Sun has also found a method to create thick films of the material; important, as conductivity increases with film thickness. Sun has also shown that the circuits can function for long periods, both in the presence of oxygen and water.

“This may appear to be a small advance in a specialised field,” Fabiano noted, “but it has major consequences for many applications. We can now construct complementary logic circuits – inverters, sensors and other components – that function in moist surroundings.”

Professor Magnus Berggren added: “With an n-type material in our toolbox, we can produce complementary circuits that occupy the available space much more efficiently, since resistors are no longer required in the logical circuits.”

Alongside bioelectronics, applications include logic circuits that can be printed on textile or paper, low cost sensors and flexible displays.