April 25, 2017

Graphene and Gold Make a Better Brain Probe

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Photograph courtesy of Daegu Gyeongbuk Institute of Science & Technology.

Scientists have created more flexible neural electrodes that minimize tissue damage and still transmit clear brain signals. Brain-machine interfaces, in which electrodes placed in the brain record neural activity, can help control prosthetic limbs, but progress is hindered by limitations in electrodes, which are relatively stiff and can damage soft brain tissue. Researchers at Daegu Gyeongbuk Institute of Science & Technology, South Korea, found that a probe made of graphene and gold read rat brain signals much better than a standard flat, gold electrode.

Designing smaller, gentler electrodes that still pick up brain signals is a challenge because brain signals are so weak. Typically, the smaller the electrode, the harder it is to detect a signal. However, the research team developed new probes that are small, flexible, and read brain signals clearly. The probe consists of an electrode that records the brain signal. The signal travels down an interconnection line to a connector, which transfers the signal to machines measuring and analyzing the signals. The electrode starts with a thin gold base. Attached to the base are zinc oxide nanowires that are coated in a thin layer of gold, and then a layer of conducting polymer called PEDOT. These combined materials increase the probeís effective surface area, conducting properties, and strength of the electrode, while still maintaining flexibility and compatibility with soft tissue.

Packing several long, thin nanowires onto one probe enables the scientists to make a smaller electrode that retains the same effective surface area of a larger, flat electrode, without reducing signal detection. The interconnection line is made of a mix of graphene, which is flexible, and gold, which is an excellent conductor.

The probe requires further clinical tests before widespread commercialization. The researchers are also interested in developing a wireless version to make it more convenient for a variety of applications. The study was published online March 7 in ACS Applied Materials and Interfaces.

Editorís note: This story was adapted from materials provided by Daegu Gyeongbuk Institute of Science and Technology.

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