本文關(guān)鍵詞： fNIRS 并行采集技術(shù) 鎖定放大技術(shù) 移相電路 高精度模數(shù)轉(zhuǎn)換模塊　出處：《電子科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：功能近紅外光譜成像技術(shù)(fNIRS)是一種非侵入式、高時(shí)間分辨率的腦功能活動(dòng)檢測(cè)技術(shù),近年來在生物醫(yī)學(xué)領(lǐng)域和臨床研究中得到了廣泛關(guān)注。本文的主要研究?jī)?nèi)容是:研發(fā)適用于功能近紅外光譜成像技術(shù)中的多路微弱信號(hào)并行采集技術(shù)。具體實(shí)現(xiàn)方法為:以微弱信號(hào)檢測(cè)原理為理論基礎(chǔ),基于鎖定放大技術(shù)的正交檢波電路為核心,以DDS芯片的90°移相電路為輔,再增加高精度的模數(shù)轉(zhuǎn)換模塊,最終實(shí)現(xiàn)fNIRS中多路微弱信號(hào)并行采集技術(shù)。該技術(shù)可實(shí)現(xiàn)32通道血氧信號(hào)的同步采集。本文以連續(xù)波技術(shù)為基礎(chǔ),將穩(wěn)定值的入射光的光強(qiáng)疊加一個(gè)低頻調(diào)制的方波(最大頻率值為40KHz,通道間的頻率間隔為200~300Hz),以頻率值的不同來區(qū)分不同通道中腦區(qū)的血氧信號(hào),達(dá)到本文的目標(biāo):同步采集32個(gè)通道的血氧信號(hào)。本文研究的微弱血氧信號(hào)的并行采集技術(shù)與普通的血氧信號(hào)采集技術(shù)不同之處如下:1、基于連續(xù)波技術(shù)的普通血氧信號(hào)采集技術(shù)在一個(gè)時(shí)間點(diǎn)上,只有一個(gè)光源點(diǎn)亮,如果有多個(gè)光源,只能循環(huán)點(diǎn)亮所有光源。而本文研究的微弱血氧信號(hào)并行采集技術(shù)可以在同一時(shí)間上,將所有光源點(diǎn)亮,而不會(huì)有各個(gè)腦區(qū)血氧信號(hào)的時(shí)間誤差,并且按不同頻率值的方波調(diào)制信號(hào)來區(qū)分不同通道的腦區(qū)也是極其方便的。2、基于連續(xù)波技術(shù)的普通血氧信號(hào)采集技術(shù),一般采用低精度的高速模數(shù)轉(zhuǎn)換芯片,使其采集到的不同腦區(qū)的血氧信號(hào)近似在同一時(shí)間內(nèi)取得。而本文由于采用頻分復(fù)用技術(shù),必須將所有同一時(shí)間得到的血氧信號(hào)同時(shí)進(jìn)行模數(shù)轉(zhuǎn)換。本文采用多個(gè)高精度低速的模數(shù)轉(zhuǎn)換芯片組成模數(shù)轉(zhuǎn)換模塊,可以達(dá)到同時(shí)將所有通道的血氧信號(hào)進(jìn)行模擬信號(hào)到數(shù)字信號(hào)的轉(zhuǎn)換,以便在上位機(jī)中進(jìn)行實(shí)時(shí)顯示、存儲(chǔ)或進(jìn)行進(jìn)一步的信號(hào)處理。文章末尾以fNIRS子系統(tǒng)數(shù)學(xué)模型的具體參數(shù)來說明電路板的性能,并且通過Milk-ink實(shí)驗(yàn)驗(yàn)證了所研究的fNIRS中多路微弱信號(hào)并行采集技術(shù)在實(shí)際應(yīng)用中的真實(shí)性和有限性,八通道的微弱信號(hào)并行采集電路板已經(jīng)通過調(diào)試,從而驗(yàn)證了本人在研究生期間所研究的成果:fNIRS中多路微弱信號(hào)并行采集技術(shù)。
[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 擄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.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：R445.7;TN911.23

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相關(guān)期刊論文 前1條

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本文編號(hào)：1522125