fNIRS中多路微弱信号并行采集技术

发布时间：2018-02-21 14:28

本文关键词： fNIRS 并行采集技术锁定放大技术移相电路高精度模数转换模块　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：功能近红外光谱成像技术(fNIRS)是一种非侵入式、高时间分辨率的脑功能活动检测技术,近年来在生物医学领域和临床研究中得到了广泛关注。本文的主要研究内容是:研发适用于功能近红外光谱成像技术中的多路微弱信号并行采集技术。具体实现方法为:以微弱信号检测原理为理论基础,基于锁定放大技术的正交检波电路为核心,以DDS芯片的90°移相电路为辅,再增加高精度的模数转换模块,最终实现fNIRS中多路微弱信号并行采集技术。该技术可实现32通道血氧信号的同步采集。本文以连续波技术为基础,将稳定值的入射光的光强叠加一个低频调制的方波(最大频率值为40KHz,通道间的频率间隔为200~300Hz),以频率值的不同来区分不同通道中脑区的血氧信号,达到本文的目标:同步采集32个通道的血氧信号。本文研究的微弱血氧信号的并行采集技术与普通的血氧信号采集技术不同之处如下:1、基于连续波技术的普通血氧信号采集技术在一个时间点上,只有一个光源点亮,如果有多个光源,只能循环点亮所有光源。而本文研究的微弱血氧信号并行采集技术可以在同一时间上,将所有光源点亮,而不会有各个脑区血氧信号的时间误差,并且按不同频率值的方波调制信号来区分不同通道的脑区也是极其方便的。2、基于连续波技术的普通血氧信号采集技术,一般采用低精度的高速模数转换芯片,使其采集到的不同脑区的血氧信号近似在同一时间内取得。而本文由于采用频分复用技术,必须将所有同一时间得到的血氧信号同时进行模数转换。本文采用多个高精度低速的模数转换芯片组成模数转换模块,可以达到同时将所有通道的血氧信号进行模拟信号到数字信号的转换,以便在上位机中进行实时显示、存储或进行进一步的信号处理。文章末尾以fNIRS子系统数学模型的具体参数来说明电路板的性能,并且通过Milk-ink实验验证了所研究的fNIRS中多路微弱信号并行采集技术在实际应用中的真实性和有限性,八通道的微弱信号并行采集电路板已经通过调试,从而验证了本人在研究生期间所研究的成果:fNIRS中多路微弱信号并行采集技术。
[Abstract]:Functional near Infrared Spectroscopy (FNIRS) is a noninvasive, high time resolution brain activity detection technique. In recent years, it has received extensive attention in the field of biomedical and clinical research. The main research contents of this paper are as follows: research and development of multi-channel parallel acquisition technology of weak signals suitable for functional near infrared spectral imaging. The method is: based on the principle of weak signal detection, The quadrature detection circuit based on locking amplification technology is used as the core, the 90 掳phase shift circuit of DDS chip is used as the supplement, and the high precision A / D conversion module is added. Finally, the parallel acquisition technology of multi-channel weak signals in fNIRS is realized, which can realize the synchronous acquisition of 32-channel oxygen signals. This paper is based on continuous wave technology. A low-frequency modulated square wave (the maximum frequency is 40kHz and the frequency interval between channels is 200kHz) is superimposed on the intensity of the incident light with a stable value. The different frequency values are used to distinguish the blood oxygen signals in the brain region of different channels. To achieve the goal of this paper: to simultaneously collect 32 channels of blood oxygen signal. The parallel acquisition technology of weak oxygen signal in this paper is different from that of common blood oxygen signal acquisition technology as follows: 1, common blood based on continuous wave technology. Oxygen signal acquisition technology at a point in time, There is only one light source to light, if there are more than one light source, only all light sources can be illuminated circularly. And the parallel acquisition technology of weak blood oxygen signal in this paper can light all the light sources at the same time. It is also very convenient to distinguish the brain regions with different channels according to the square wave modulation signals of different frequencies. 2. The common blood oxygen signal acquisition technology based on continuous wave technology. A low precision high speed A / D conversion chip is generally used to obtain the blood oxygen signals in different brain regions at approximately the same time. However, the frequency division multiplexing technique is used in this paper. All the blood oxygen signals obtained at the same time must be converted at the same time. In this paper, several high precision and low speed A / D conversion chips are used to form the A / D conversion module. At the same time, all channels of oxygen signal can be converted from analog signal to digital signal, so that real-time display can be carried out on the upper computer. Storage or further signal processing. At the end of the article, the performance of the circuit board is explained by the specific parameters of the mathematical model of the fNIRS subsystem. The Milk-ink experiment proves the authenticity and finiteness of the multi-channel parallel acquisition of weak signals in fNIRS. The 8-channel circuit board for parallel acquisition of weak signals has been debugged. Thus, the parallel acquisition technique of multi-channel weak signal is verified in the research result: FNIRS.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R445.7;TN911.23

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