监测脑电α波的无线传感器网络系统

背景:临床上一般采用多导睡眠记录仪监测脑电α波来研究失眠等问题.多导睡眠记录仪存在两个问题:①众多长导线严重束缚被试者,导致其不能正常睡眠,影响了身心状态.无法获得准确结果.②由于脑电信号是极其微弱的电生理信号,所以非常容易被交流电干扰,使得分析软件无法识别有用信号.因此,需要设计一种能够克服上述缺点的监测系统.目的:设计一种监测脑电信号的无线传感器网络系统,不影响被试者身心状态,获得不受干扰的、准确的脑电信号.设计:采用先进行理论分析,建立电路模型,再设计实现实际应用电路.单位:解放军第三○五医院.材料:解放军第三○五医院提供临床实验环境.北京新兴阳升科技有限公司生产的多导睡眠记录仪做为对比实验设备.采用Matlab软件系统设计分析软件.方法:首先于2005年在解放军第三○五医院进行理论分析,建立干扰模型和无线传感器网络系统模型.2006年根据电路模型,设计实现了能够有效抑制干扰和小体积的无线脑电传感器.实验设计的无线脑电传感器于2006-02/08在解放军第三○五医院完成实际使用观察,此次使用过程经医院伦理委员会批准,受试者为院内工作人员.对实验的目的、过程、结果完全知情同意.最后将实际使同结果与多导睡眠记录仪的记录结果进行对比.主要观察指标:在干扰环境下获得信号的频谱.结果:无线脑电传感器在干扰条件下获得的脑电信号在8～12 Hz的α波频率范围内的功率谱峰值为6 926.043,交流电干扰在50 Hz的 频率上的功率谱为0.356.同时使用多导睡眠记录仪获得的脑电信号在8～12 Hz的α波频率范围内的功率谱峰值为1 112.3,交流电干扰在50 Hz的频率上的功率谱为85 440.结论:系统能够获得良好的脑电α波信号,并且很好地抑制交流电干扰.

A wireless sensor network system for monitoring electroencephalogram alpha band

BACKGROUND: Clinical study of insomnia is performed by monitoring the alpha wave of the brain signals with the polysomnography (PSG). PSG has two deficiencies in recording electroencephalogram (EEG): ①The testee is wrapped by long electrode wires so that they cannot sleep normally. As a result, the testee's mental and physical status is affected and the results are inaccurate. ②As the alpha wave consists of very weak biomedical signals, it is easily affected by the alternating current (AC) interference, so that the analytical software cannot identify the desired signals. For these reasons, a monitoring system that overcomes such deficiencies is needed. OBJECTIVE: To design a wireless EEG sensors system for detecting brain signals. It can obtain the brain signals in an accurate and non-disturbed way without affecting the testee's mental and physical status. DESIGN: The actual application circuit was implemented after analyzing and building the circuit model. SETTING: The 305 Hospital of Chinese PLA.MATERIALS: The clinical experimental environment was provided by the 305 Hospital of Chinese PLA. The PSG made by Beijing Rising Sun Science-Tech Co., Ltd. was served as experimental instrument for comparison test and analytical software was designed by MATLAB.METHODS: Theoretical analysis was performed at the 305 Hospital of Chinese PLA in 2005 to create the anti-interference model and the wireless EEG sensors system model. In 2006, the circuit model helped us realize the small-sized wireless brain wave sensor that could suppress the interference effectively. The sensor was put into practical use at the 305 Hospital of Chinese PLA from February to August 2006. The experiment was approved by the hospital ethics committee. The volunteer testees were those who worked in the hospital and they had full knowledge of the objective, process and results of the experiment. Besides, those signals were compared with what the PSG recorded. MAIN OUTCOME MEASURES: Frequency spectrum of signals obtained in interference environment. RESULTS: For the brain signals that were captured by the wireless EGG sensors in the presence of interference, the power spectrum peak value was 6 926.043 within the alpha wave ranged at 8-12 Hz. For the AC interference, the power spectrum peak value was 0.356 at 50 Hz. Meanwhile, for the brain signals that were captured by the PSG, the power spectrum peak value was 1112.3 within the alpha wave ranged at 8-12 Hz; for the AC interference, the power spectrum peak value was 85 440 at 50 Hz.CONCLUSION: The system can obtain satisfying brain alpha wave signals and can suppress AC interference effectively.