New Silicon Device Enables Scientists to Monitor Neuron Activity

Stanford University researchers have developed a new device that enables them to observe real-time neural activity in the brain.

The researchers published their work on the device in Science Advances. Lead author and materials science & engineering graduate student Abdulmalik Obaid revealed how they designed new processes to create 3D silicon electronics that scales up easily. The device has microwires measuring smaller than half a human hair's width; hundreds of these wires are inserted in the brain and are directly connected to a chip, which records brain signals that pass each wire.

Co-senior author and professor Nick Melosh stated that electrical activity counts as among the highest-resolution data that can come from brain activity. He revealed how the microwire array could enable them to monitor the activity of individual neurons.

In the study, the scientists described how the device's interface was tested on retinal cells of rats and brains of mice, where they were able to collect meaningful electrical signals. They are now determining how these signals can provide knowledge on learning and its application in as part of prosthetics, specifically speech assistance.

The researchers used silicon technology to make the device durable and will cause minimal brain damage. Melosh stated that silicon chips are powerful and can also scale up well. The technology is simple, he adds, where one can take the silicon chip and press it on the end of the microwire bundle and get signals.

In the paper, the researchers described how the structure of the array needed to be durable and strong so they could be wrapped individually in a biologically-safe polymer before bundling them within a metal collar. This process orients and spaces apart the wires properly. There is no polymer below the collar, as it is part of the wires that are connected to the brain.

The study also explained how such a device with a brain-machine interface could only have about a hundred wires with a hundred signal channels, and each is put in the array manually. Years were spent in refining the design and formulating techniques for fabrication to create an array that can have thousands of channels. It is an effort that has the partial financial support of the Wu Tsai Neurosciences Institute.

According to neurosurgery and neurology assistant professor and co-author Jun Ding, the device's design is such that it can record various brain regions simultaneously at various depths with any 3D arrangement. He added that this device would significantly improve our understanding of how the brain functions during illnesses and good health.

Obaid revealed how they spent years working out the design using silicon chips, and it was a delight because it already worked the very first time they tested it on the retina.

They are now on the next stage wherein they will conduct long-term studies to determine the array's durability and performance in larger versions. They also want to explore how they can apply the signals and what they represent. So far, they have been able to monitor how the brain fires up during learning and failures. They envision the device to help improve medical devices like mechanical prosthetics as well as vision and speech assisting devices.