Brain Machine Interfaces Go Wireless

By eliminating the need for wires going through the brain, wireless brain machine interfaces reduce the risk of infections.

AsianScientist (Feb. 22, 2016) – A research team from Japan has developed a wafer-thin silicon chip for use in brain-machine interfaces (BMIs). This innovation may contribute to the development of safer BMI systems with less risk of infection. The article was published in Sensors.

Human and animal brain cells generate slight neural signals with every movement, which are recorded by BMIs. Such neural recording systems use wires to connect the implanted device through the opening in the skull to an external device. However, this opens up the possibility of infections.

One way of solving this issue is to develop a wireless neural interface that is fully implantable on the brain. However, the neural interface implanted on the brain surface should be small and minimally invasive. Furthermore, it will require a power source, antenna for wireless communication and many functional circuits.

Th research team at the Department of Electrical and Electronic Information Engineering at Toyohashi University of Technology has thus developed a wafer-level packaging technique to integrate a silicon large-scale integration chip in a very thin film (10 μm thick). The chip is part of a wireless power transmission device which has a flexible antenna and rectifier chip.

First author and PhD candidate Kenji Okabe said, “We have investigated how to integrate flexible antenna and high-performance circuits and tried this fabrication method with process conditions obtained through experiments.”

Assistant Professor Ippei Akita, who is leading the project, said, “Using flexible device technology is a good solution to implement bio-compatible passive devices such as antennas or sensor electrodes.

“On the other hand, silicon-based integrated circuit technology, which has a long history, is suitable for ultra-low-power systems with many functionalities. So, we believe that combining these technologies is essential to establish such minimum invasive implantable devices.”

97 percent of the device area is composed of a flexible film as the silicon chip is incredibly small. Therefore, it is flexible enough to fit the shape of the brain surface. In addition, the researchers engineered the wireless power transmission device to be able to be immersed in saline. This device can also supply electricity to other circuits included in the neural interface.

At the moment, the researchers are working to integrate more functions to the large-scale integration chip.

The article can be found at: Okabe et al. (2015) Co-design Method and Wafer-level Packaging Technique of Thin-film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-powered Neural Interface Systems.


Source: Tohoyashi University of Technology.
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