Graphene electrodes could enable higher quality imaging of brain cell activity thanks to new research by a team of engineers and neuroscientists. The researchers developed a technique, using platinum nanoparticles, to lower the impedance of graphene electrodes by 100 times while keeping them transparent.

Low-impedance, transparent graphene microelectrode array. (Credit: UC San Diego)

In tests on transgenic mice, the low-impedance graphene electrodes were able to record and image neuronal activity, such as calcium ion spikes, at both the macroscale and single cell levels. The advance brings graphene electrodes a step closer to being adapted into next-generation brain imaging technologies and various basic neuroscience and medical applications.

Another important aspect of this work is that it is the first to uncover the root of graphene's high impedance — a fundamental property called quantum capacitance. Researchers also determined an amount of platinum nanoparticles that was just enough to lower impedance while keeping transparency high. With their method, the electrodes retained about 70 percent of their original transparency. Next steps include making the electrodes smaller and incorporating them into high density electrode arrays.

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