For neural research, the wireless chip lights up the brain

Researchers have developed a chip that is wirelessly powered and can be surgically implanted to read neural signals and stimulate the brain with light and electric current. The technology has been successfully demonstrated in rats and is designed to be used as a research tool.

“Our goal was to create a research tool that can be used to help us better understand the behavior of different brain regions, particularly in response to various forms of neural stimulation,” says Yaoyao Jia, corresponding author of a paper on the work. and an assistant professor of electrical and computer engineering at North Carolina State University. “This tool will help us answer fundamental questions that could then pave the way for advances in addressing neurological disorders such as Alzheimer’s or Parkinson’s.”

The new technology has two characteristics that distinguish it from the previous state of the art.

First, it’s completely wireless. Researchers can power the 5 × 3 mm2 chip, which has an integrated power receiver coil, by applying an electromagnetic field. For example, in the researchers’ tests with laboratory mice, the electromagnetic field surrounded each rat’s cage, so the device was fully powered regardless of what the rat was doing. The chip is also capable of sending and receiving information wirelessly.

The second feature is that the chip is trimodal, which means it can perform three tasks.

Current state-of-the-art neural interface chips of this type can do two things: they can read neural signals in targeted regions of the brain by detecting electrical changes in those regions; and they can stimulate the brain by introducing a small electric current into brain tissue.

The new chip can do both, but it can also light up brain tissue, a function called optical stimulation. But for optical stimulation to work, you first need to genetically modify the targeted neurons to make them respond to specific wavelengths of light.

“When you use electrical stimulation, you have little control over where the electrical current goes,” Jia says. “But with optical stimulation, you can be much more precise, because you’ve only modified those neurons you want to target to make them sensitive to light. This is an active research field in neuroscience, but the field has lacked electronic tools that it has. need to move forward. This is where this work comes in. “

In other words, by helping researchers (literally) shed light on neural tissue, the new chip will help them (figuratively) shed light on how the brain works.

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The paper, “A Trimodal Wireless Impantable Neural Interface System-on-Chip”, is published in the journal IEEE transactions on biomedical circuits and systems. The paper was written in collaboration with Ulkuhan Guler of the Worcester Polytechnic Institute; Yen-Pang Lai of Georgia Tech; Yan Gong, Arthur Weber, and Wen Li of Michigan State University; and Maysam Ghovanloo of Bionic Sciences Inc.

The work was done with support from the National Science Foundation (NSF) with a 2024486 grant. The work was also supported by NC State’s NSF-funded ASSIST Center with an CEE-1160483 grant. The mission of the ASSIST Center is to create self-powered wearable devices that can detect long-term multimodal sensing without having to replace or charge the batteries.