Real-time brain activity measurement and signal processing system using highly sensitive MI sensor

Kewang Wang,Michiharu Yamamoto,Changmei Cai,Tsuyoshi Uchiyama

doi:10.1063/1.4974528

Abstract

Superconducting Quantum Interference Devices (SQUIDs) are the most used sensor to detect the extremely weak magnetic field of brain. However, the sensor heads need to be kept at very low temperature to maintain superconductivity, and that makes the devices large-scale and inconvenient. In order to measure brain activity in normal environment, we had constructed a measurement system based on highly sensitive Magneto-Impedance (MI) sensor, and reported the study of measuring Auditory Evoked Field (AEF) brain waves. In this study, the system was improved, and the sensor signals can be processed in real-time to monitor brain activity. We use this system to measure the alpha rhythm in the occipital region and the Event-Related Field (ERF) P300 in the frontal, the parietal and both the temporal regions.

Highlights

Advance in structural and functional research of brain gave us a more profound understanding of our brains in the past few decades and more and more programs are committed to research in this field
The Brain Computer Interfacing (BCI) technology based on real-time brain signal processing, contributed in numerous fields
On P300 measurement, we referred to other results of MEG research based on visual stimuli elicited P300,9 and our past study,[10] the deflections can be elicited by Target stimuli but not by Standard stimuli around 300-400 ms and the results showed similar characteristics to our results in this study

Summary

Introduction

Advance in structural and functional research of brain gave us a more profound understanding of our brains in the past few decades and more and more programs are committed to research in this field. The neuroprosthetics can be used in neural repair and rehabilitation, even substituting the non-functional arm or leg of those people with disabilities.[2] Measuring and analyzing the brain activity in real-time could have wide applications for healthy users, such as driver drowsiness detection or video game interaction. Magnetoencephalography (MEG) is an established technique for measuring brain magnetic field and arrays of Superconducting Quantum Interferential Devices (SQUIDs) are currently the most widely used sensors for MEG because of the high sensitivity and accuracy. The SQUIDs need to be kept in a liquid nitrogen or liquid helium environment to maintain superconductivity during measurement, and that makes the devices large-scale and inconvenient. The circuit is mostly based on CMOS IC It makes the structure simpler and has a lower power cost.[3,4]

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