R&D News & Events

Jelly with a Memory

Author: Alan Boyd

We are becoming more attached to our technology, but what if we could actually be attached to it? Until now, a key issue in bioelectronics has been how to take conventional electronics made from hard, unbending materials that tend to perform poorly in wet conditions and place them in the soft, flexible and wet environment of cells or tissues. Now, a team of chemical and biomolecular engineers at North Carolina State University have created a device that may be the first step in fusing electronics with biological systems.

The device has electrodes of gallium and indium metals, both of which are liquids at room temperature, set within a conductive, water-based gel. Its consistency lies somewhere between raw jelly and a bendy ruler. The device has conductive and non-conductive states, which are used to represent a binary system of ones and zeroes. It uses ions (charged molecules) to create the states, in the same way that conventional electronics uses electrons. The device’s memory comes from its ability to store the state after the stimulus (in this case ions) is gone.

To produce a non-conductive state, an electrode is exposed to a positive charge, producing an oxidized layer on the electrode, which is resistive to electricity. For a conductive state, a negative charge is applied, removing the oxidization. The negative charge would normally cause positive charge to move across the electrode, oxidizing it and leaving the device in a permanently non-conductive state. To prevent this, the team changed the chemical composition of one side of the gel. As a result, solely the second electrode determines the state.

The prototype shows great potential for developing biological sensors that would be embedded in the body and allow medics and researchers to continuously monitor biological systems. The electrodes’ malleability and the gel’s biocompatibility mean that the device could perform more robustly in biological environments than its hard, metallic counterparts. Perhaps more exciting is this technology’s potential for mimicking the brain; recent work has drawn parallels between similar types of memory devices and neural systems.

Original paper at http://onlinelibrary.wiley.com/doi/10.1002/adma.201101257/pdf

Photo credit: Michael Dickey, North Carolina State University

Posted on Wednesday, 17th August, 2011