Semi-flexible optoelectrodes for high-resolution neuron reading and stimulation with little damage – archyde

The use of electrodes in the brain of laboratory samples has led neuroscience to new discoveries for decades. Common silicon-based electrodes are based on established manufacturing processes, but are stiff and prone to brain damage. More flexible polymer-based electrodes avoid these problems, but are difficult to scale, especially when light emitters are incorporated for neuron stimulation.

Researchers at the Lawrence Berkeley National Laboratory have developed an optoelectrode assembly technique that offers the best of both worlds. In AIP Publishing’s Journal of Vacuum Science & Technology B, the scientists demonstrated that it is possible to efficiently manufacture a semi-flexible light-emitting electrode by removing the rigid silicon material from under the tip of the probe.

The resulting device, called an optoelectrode, can examine deep brain tissue at high resolution, record signals from individual nerve cells and stimulate small groups of neurons using state-of-the-art techniques such as fiber optics.

“Implanting polymer probes in the brain is challenging, but we have developed a very simple manufacturing technique to address it,” said author Vittorino Lanzio. “Insertion is less difficult because they don’t have to be glued to a silicon or tungsten shuttle, which increases the footprint of the device when inserting.”

Optoelectrodes are currently reserved for short-term use in laboratory animals. While the new electrode is an important step towards better biocompatibility, much more needs to be developed to enable people to use the electrode over the long term.

The tiny movements of breath and the pulsation of blood flow subtly get the brain going, even when at rest. Microscopic displacements can affect the performance of an electrode and damage brain structures. These injuries can alert immune cells that are interfering with electrode function.

The consistency of the brain is even more limp than jelly. “

Stefano Cabrini, Author

The optoelectrode consists of oxide glass and nitride, which is initially bound to silicon. The group uses a nanoscale etching technique to remove the silicon underneath the device bay area.

The team tested the device through experiments on rats and found that the semi-flexible device, which contains 64 individual electrodes and high-density photonics in a significantly smaller cross-sectional area, could be inserted into a rat’s brain without the use of a silicon or tungsten shuttle.

The researchers hope neuroscientists will get the new device working and, as the field progresses, integrate more functions into the electrodes, such as microfluidics to move chemicals into the brain.


Journal reference:

Lanzio, V., et al. (2021) Neural Optoelectrodes Merging Semiconductor Scalability with Polymer-Like Flexibility for In Vivo Acute Neuron Readout and Stimulation with Little Damage. Journal of Vacuum Science and Technology B.


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