基于晶体相位调制原理研究具有高信噪比、高灵敏度的低频脑电检测方法

Electroencephalography (EEG) measurement technology has become one of key methods of brain science research because it can provide frequency space dynamic information associated with specific brain state. In order to obtain EEG signals with high signal to noise ratio (SNR) and high sensitivity, the research is done that include the measurement mechanism of extremely-low-frequency EEG based on phase modulation of optical crystal, the mechanism of interaction between the heterogeneous composite electrode and the ion current of the brain, and the method of suppressing EEG measurement signal noise. In order to solve three key problems, which are low conversion efficiency between extremely-low-frequency EEG and input light parameters, the high contact impedance between dry electrode and scalp, and the serious noise disturbance of EEG monitoring system, a multi-channel optical EEG sensor, a composite integrated passive flexible dry electrode, and an EEG artifact removal algorithm are proposed. Through these research, the physical mechanism between incident beam and weak EEG in the range of extremely-low-frequency is revealed and we enhance the acquisition sensitivity and SNR of EEG. Our research will not only lay a theoretical foundation for measurement of EEG, but also provides an idea for the measurement of other low frequency and weak signals.

脑电检测技术由于脑电信号能提供与特定大脑状态关联的频率空间动态信息而成为脑科学研究的核心手段。为了获取具有高信噪比、高灵敏度的脑电信号，本项目研究了基于光学晶体相位调制原理的低频EEG检测机理和异质复合材料电极与脑离子电流之间的作用机制，并提出抑制脑电检测信号噪声的方法。针对低频脑电信号与输入光波参数之间转化效率低，干电极与头皮之间电子通道接触阻抗高和脑电测试系统噪声干扰严重的关键问题，本项目提出了一种新型多通道EEG检测光学传感器，一种基于复合材料的一体化无源柔性干电极以及脑电采集信号伪迹去除算法。以上研究揭示了光信号和低频、弱幅脑电信号之间作用的调制机理，实现了具有高检测精度、高信噪比的脑电信号检测。通过本项目的研究，不仅为脑电信号的检测奠定理论研究基础，还为其他低频、弱信号的检测提供一种思路。

脑电检测技术是脑科学研究的关键技术之一，如何获得高信噪比、高灵敏度的脑电信号成为脑电信号检测关键科学问题。围绕关键科学问题，课题组寻找了适合制作柔性干电极的新型复合材料，确定电极的制作与加工方案，以完成柔性干电极的制作；研究了电极与头皮间接触形式对阻抗大小的影响，并研究降低干电极与头皮之间电子通道接触阻抗的方法；在脑电信号传感研究方法，课题组探究了基于等离子波导的生物电传感器，以及基于光学晶体的输入光波参数与脑电信号之间的调制模式，建立两者之间相互作用的数学模型，并分析影响输出光信号功率的因素与噪声源，提出抑制内、外噪声的方法；探索了基于光学Fano共振原理的光子晶体侧耦合型脑电传感器的实现方法，完成脑电检测系统及相应光学、信号处理模块的设计，并搭建基于光学原理的脑电检测系统，验证系统可行性和进行系统小型化的研究。