脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)

1、 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)(文檔含英文原文和中文翻譯)譯文：脈搏傳感器及電路設(shè)計(jì)脈診具有 2600 多年臨床實(shí)踐 ,是我國(guó)傳統(tǒng)中醫(yī)四診中的精髓。脈搏信息在中醫(yī)、西醫(yī)中都有著十分重要意義。在傳統(tǒng)中醫(yī)脈診中 ,切脈技巧復(fù)雜難以掌握和運(yùn)用 ,醫(yī)生主觀因素影響也較大 , 隨著科學(xué)技術(shù)的發(fā)展 , PVdF (聚偏二氟乙烯)壓電薄膜的研制確定了不同的脈象儀用于脈診的客觀化，本設(shè)計(jì)的脈象儀傳感器的敏感部分是人手指。本文將從模擬中醫(yī)脈診的角度 ,研制了 PVdF 壓電位體積能獲得大的輸出功率。因?yàn)閾Q能器單位體薄膜傳感器 ,并應(yīng)用于脈象儀研究。積最大輸出功率正比于

2、機(jī)電耦合系數(shù)和能承受的定量化已成為中醫(yī)診斷的必然趨勢(shì)。幾十年來 ,國(guó)家1 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)選擇 PVdF 壓電薄膜 ,因?yàn)樗腥缦聨讉€(gè)的優(yōu)點(diǎn)：首先，膜輕且柔韌 ,易于制備 ,與人體組織的阻抗耦合性好 ,能緊貼皮膚 ,使得脈搏信號(hào)通過薄膜而不失真。另外由于薄膜類似于人類皮膚 ,可以制作仿生觸覺傳感器。壓電常數(shù)大 ( d33 = 20 pC/ N) ,變力易于研究 ,但從研制情況看 ,大部分傳感器不能模擬中敏度。比石英晶體高 10 倍 ,壓電電壓輸出常數(shù)切脈時(shí)所取三部 ,按、浮、寸三種診法，g = 174 是所有壓電體中最高的。檢測(cè)脈搏信號(hào) ,主要靠壓力定標(biāo) ,適用性不夠好。其

3、次，機(jī)械品質(zhì)因素低 ,阻尼小 ,密度低 ,具有寬帶特性 ,能滿足脈搏信號(hào)的頻率特性。在非常高的交變電場(chǎng)中不至于去極化。由于 PVdF 膜的柔性及其厚度方向伸縮振動(dòng)的諧振頻率很高 ,使得在很寬范圍內(nèi)有平坦的頻率。基于 PVdF 膜的以上優(yōu)點(diǎn) ,根據(jù)中醫(yī)切脈模式 ,我們研制出了三點(diǎn)式的傳感器 ,三個(gè)換能器分別由 PVdF 薄膜作成正方形片狀 ,面積相當(dāng)于切脈時(shí)指腹的受力面積，在壓電薄膜電荷生成的兩極分別蒸鍍鋁電極并引出導(dǎo)線 ,用柔性有機(jī)塑料薄膜封裝并做成圓形基片，裝在一根表帶上。考慮到患者體征、老幼等因素 ,三個(gè)換能器獨(dú)立地對(duì)應(yīng)于按、浮、寸三個(gè)部位 ,且能在表帶上縱橫調(diào)節(jié)。測(cè)量時(shí)表帶束在腕部，醫(yī)生

4、手指對(duì)應(yīng)的放大三個(gè)換能器即可。醫(yī)生可以透過薄片感覺到脈搏的波動(dòng)。根據(jù)浮、中、沉模式把脈過程中可以人為地控制力度，做到因人而異克服以往缸體換能器壓力定標(biāo)所取浮不足。當(dāng)周期性脈搏壓力作用在換能器上時(shí)，將機(jī)械能轉(zhuǎn)換為電能。脈象頻譜分析表明脈象能譜中 99 %的能量集中在 10 Hz 以下 ,最高頻率不超過 40 Hz。調(diào)實(shí)現(xiàn)與微機(jī)的通信。PVdF 壓電薄膜換能器是本設(shè)計(jì)中的敏感部件 ,也是設(shè)計(jì)的關(guān)鍵環(huán)節(jié)之一 ,作用是能模擬其中人的壓覺 ,將微弱低頻的脈搏壓力信號(hào)轉(zhuǎn)換成電信號(hào)。設(shè)置前置電荷放大器作用有二 :一是與換能器阻抗匹配 ,把高阻抗輸入變?yōu)榈妥杩馆敵?；二是將微弱電荷轉(zhuǎn)換成電壓信號(hào)并放大。為了提高

5、測(cè)量的精度和靈敏度 ,前置放大電路采用了線性修正的電荷放大電路 ,以獲得較低的下限頻率 ,消除電纜的分布饋電容。電容對(duì)靈敏度的影響 ,使設(shè)計(jì)的傳感器體積小型化。第一個(gè)低通濾波電路由 R1 和 C1 組成，截止頻率約為 1000Hz ,以使脈搏信號(hào)的高次諧波能通過 ,讓脈搏信號(hào)反映的病理性特征信息得到完整的保留。同時(shí)該上限截止頻率和時(shí)間常2 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)數(shù)電路(由 C2 和 R2 組成)還會(huì)決定性地影響脈搏波形的失真度。如果電路的時(shí)間常數(shù)選得過小 ,會(huì)造成信號(hào)的低頻分量嚴(yán)重衰減和移相。實(shí)驗(yàn)表明 ,當(dāng)時(shí)間足以保證脈搏波的低頻分量不會(huì)失真。電壓放大器主要是對(duì)電荷放大器輸出的電

6、壓信號(hào)放大。并提供不同的增益。根據(jù)我們的經(jīng)驗(yàn) ,設(shè)置上限截止頻率為 100Hz 比較理想。工頻陷波器環(huán)節(jié)是為了濾除市電 50HZ 干擾。電容應(yīng)選鉭電容作補(bǔ)償電容，對(duì)市電噪聲采取了硬件工頻陷波和軟件濾波并用的措施 ,實(shí)驗(yàn)證明 ,利用數(shù)字濾波技術(shù) ,對(duì)工頻干擾信號(hào)的抑制效果較好，對(duì)電磁信號(hào)抑制主要采取了兩種方法 ,一是對(duì)信號(hào)線進(jìn)行屏蔽 ,二是設(shè)計(jì)四階巴特沃斯低通濾波器 ,截止頻率為 100 Hz。對(duì)于人體的抖動(dòng)噪聲主要是通過軟件濾波加以濾除 ,主要是采用了防脈沖干擾平均值濾波法。該算法在凌陽單片機(jī)內(nèi)實(shí)現(xiàn) ,其基本思想是把測(cè)量得到的 256 個(gè)數(shù)據(jù)看成一隊(duì)列 ,每進(jìn)行一次新的測(cè)量 ,就把測(cè)量結(jié)果放入

7、隊(duì)尾 ,而剔除原來隊(duì)首的一次數(shù)據(jù) ,這樣在隊(duì)列中始終有 256 個(gè)“最新”數(shù)據(jù) ,對(duì) 256 個(gè)數(shù)據(jù)逐個(gè)比較大小 , 去掉其中的最大值和最小值 ,然后計(jì)算 254 個(gè)數(shù)據(jù)的平均值。這種濾波方法對(duì)周期性干擾有良好的抑制作用 ,還能對(duì)濾除脈診過程中人體偶爾的抖動(dòng)產(chǎn)生的干擾。實(shí)驗(yàn)中發(fā)現(xiàn) ,盡管人的體溫基本保持恒定 ,但手腕部位皮膚表面的溫度受外界溫度變化的影響仍很大 ,而且手腕部位皮膚與傳感器表面的溫差也會(huì)給測(cè)量帶來很大影響除溫度效應(yīng)利用人體脈搏 (1 Hz 左右)熱電噪聲信號(hào)。,需要消由于人體的脈搏信號(hào)具有頻率低、幅度小干擾大，不穩(wěn)定度低，隨機(jī)性強(qiáng)等特點(diǎn)，使得對(duì)脈搏信號(hào)的采集放大電路的設(shè)計(jì)提出了很

8、嚴(yán)格的要求，尤其是抗干擾變?yōu)槭种匾枰O(shè)計(jì)低通濾波器進(jìn)行濾波。選擇放大器時(shí)需要從增益、頻率響應(yīng)，輸入阻抗，共模抑制比，噪聲，漂移等幾個(gè)方面加以綜合考慮。 （1）抗干擾首先，工頻 50HZ 干擾及其各次諧波使用頻率為 50HZ 的市電的電子儀器設(shè)備會(huì)對(duì)檢測(cè)系統(tǒng)會(huì)產(chǎn)生較大的干擾，其幅值大約是脈搏信號(hào)峰峰值的 50%,是主要的干擾源；其次，肌電干擾肌肉的收縮會(huì)產(chǎn)生微伏級(jí)的電勢(shì)，其幅值大約是脈搏信號(hào)峰峰值的 10，維持時(shí)間大約是 50ms，頻帶范圍可以在 0HZ10000HZ；3 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)再次，由于呼吸引起的基線漂移和 ECG 幅度變化呼吸引起的基線漂移可以看成是一個(gè)以

9、呼吸的頻率加入 ECG 信號(hào)的竇性成分（正弦曲線），這個(gè)正弦成分的幅度和頻率是變化的。呼吸所引起的 ECG 信號(hào)的幅度的變化可以達(dá)到 15?；€漂移的頻率是從 0.150.3HZ。 （2）低噪聲、低漂移在脈搏信號(hào)放大器中，由于增益較高，噪聲和漂移是兩個(gè)較重要的參數(shù)。脈搏信號(hào)放大器運(yùn)行過程中的噪聲主要表現(xiàn)為電子線路的固有熱噪聲和散粒噪聲，這些都屬于白噪聲，其幅值為正態(tài)分布。為了獲得一定信噪比的輸出信號(hào)，對(duì)放大器的低噪聲性能有嚴(yán)格要求。另外，溫度變化會(huì)造成零點(diǎn)漂移，漂移現(xiàn)象限制了放大器的輸入范圍，使得微弱的緩變信號(hào)無法被放大。而脈搏信號(hào)具有很低的頻率成分，為了能正常測(cè)量，必須采取措施來限制放大器的

10、漂移。所以放大器應(yīng)選用低漂移，高輸入阻抗并且具有高共模抑制比的集成運(yùn)放電路。其它傳感器的比較 首先，壓電式傳感器目前常用的是一次性心電電極,它是用印刷方法制得的 Ag/ Agcl 傳感器。這種傳感器采用接扣與敏感區(qū)分離的方法 ,能明顯的減少由于人體運(yùn)動(dòng)產(chǎn)生的干擾。電極的好壞對(duì)采集到的心電信號(hào)質(zhì)量起著至關(guān)重要的作用 ,采用的電極應(yīng)有貼力強(qiáng),能緊附在人體表面,柔軟、吸汗、極化電壓低、導(dǎo)電性良好等特點(diǎn)。當(dāng)選用電極傳感器時(shí),需要 3 個(gè)電極分別置于左右手和左腿,構(gòu)成標(biāo)準(zhǔn)導(dǎo)聯(lián)。臨床上為了統(tǒng)一和便于比較所獲得的脈搏信號(hào),在檢測(cè)脈搏信號(hào)時(shí),對(duì)電極的位置,引線與放大器的連接方式都有嚴(yán)格的統(tǒng)一規(guī)定。目前市場(chǎng)上有

11、一種采用新型高分子壓電材料聚偏氟乙烯研制的壓電傳感器,其靈敏度高,頻帶范圍好,結(jié)構(gòu)簡(jiǎn)單,便于使用。當(dāng)手指前端受到輕微的壓力時(shí)，可以感覺到手指前端在血壓的作用下有一張一弛的感覺，將這個(gè)信號(hào)用傳感器提取出來，轉(zhuǎn)變?yōu)殡娦盘?hào)，通過指脈的波形檢測(cè)，就可以獲得人體的脈搏信號(hào)。其次，光電式傳感器血液是高度不透明的液體，光照在一般組織中的穿透性要比血液中大幾十倍，據(jù)此特點(diǎn)，采用光電效應(yīng)手指脈搏傳感器來拾取脈搏信號(hào)。反向偏壓的光敏二極管，它的反向電流具有隨光照強(qiáng)度增加而增加的光電效應(yīng)特性，在一定光強(qiáng)范圍內(nèi)，光敏二極管的反向電流與光強(qiáng)呈線性關(guān)系。指端血管的容積和透光度隨心搏改變時(shí)，4 脈搏心率測(cè)量?jī)x中英文對(duì)照外文

12、翻譯文獻(xiàn)將使光電三極管極管收到不同的光強(qiáng)，并由此產(chǎn)生的光電流均隨之作相應(yīng)變化。常用檢測(cè)脈搏的光電傳感器分為紅外對(duì)管和紅外放射管。采用紅外對(duì)管，將對(duì)管夾于手指端部，通過手指的血液濃度會(huì)隨著心臟的跳動(dòng)發(fā)生變化，紅外對(duì)管對(duì)應(yīng)的信號(hào)便會(huì)發(fā)生相應(yīng)的變化，采集此信號(hào)經(jīng)過放大，濾波，比較等處理便可以得到理想的信號(hào)。采用反射式的紅外管。現(xiàn)在市場(chǎng)上的心率計(jì)普遍采用這種傳感器來采集信號(hào)，因?yàn)榇思t外管接收和發(fā)射都在手指的同一側(cè)，因此便不用考慮每個(gè)人手指情況不同所造成的麻煩。接收的是血液漫反射回來的光，此信號(hào)可以精確地測(cè)得血管內(nèi)容積變化。再次，集成傳感器當(dāng)前,市面上有很多類型的集成心電傳感器 ,其靈敏度高,集成度高,

13、直接就可以反映出心率的變化 ,且已包含了濾波等抗干擾電路 ,波形經(jīng)過放大可以直接處理使用。缺點(diǎn)是價(jià)格非常昂貴，一般均在五百元以上，就本次設(shè)計(jì)來說，考慮到經(jīng)費(fèi)以及鍛煉自己的目的，不選擇使用該型傳感器。光電式優(yōu)點(diǎn)是靈敏度高，易于操作,響應(yīng)速度快，結(jié)構(gòu)簡(jiǎn)單。但缺點(diǎn)是1、外部光源的變化對(duì)測(cè)量結(jié)果的影響較大； 2、需要購(gòu)買專門的醫(yī)用光電傳感器，價(jià)格較貴且不易購(gòu)買；3、對(duì)這樣的器件接觸很少，對(duì)其進(jìn)行調(diào)試時(shí)可能會(huì)出現(xiàn)較大困難。壓電式優(yōu)點(diǎn)是結(jié)構(gòu)簡(jiǎn)單，實(shí)時(shí)性好，工作頻帶寬，應(yīng)用電路簡(jiǎn)單，且價(jià)格低廉。但缺點(diǎn)是直接與人體相接觸，容易因?yàn)槿梭w肌肉的顫動(dòng)等而產(chǎn)生干擾，并且容易受到外界其他信號(hào)的干擾。集成式優(yōu)點(diǎn)是集成度高

14、,包含了濾波,放大電路, 可以直接輸出信號(hào),便于操作,有效的減少了各種干擾。但缺點(diǎn)降低了本任務(wù)的難度 ,如果采用該傳感器，只需將其直接接上單片機(jī)即可實(shí)現(xiàn)功能，且價(jià)格非常昂貴?？紤]到種種情況，結(jié)合本系統(tǒng)的設(shè)計(jì)要求以及經(jīng)費(fèi)的考慮，最終選擇壓電薄膜脈搏傳感器。該傳感器價(jià)格較低，而且輸出電壓變化較為明顯，可以實(shí)現(xiàn)我們的實(shí)驗(yàn)?zāi)康?。壓電薄膜脈搏傳感器包括三個(gè)部分，鍍銀層、壓電陶瓷以及銅片。外部壓力作用于銅片時(shí)，壓電陶瓷就可以感受壓力而產(chǎn)生電信號(hào)，并最終通過鍍銀層將該信號(hào)輸出。在使用時(shí)，壓電陶瓷片要通過導(dǎo)線與電路板連接,注意在焊接壓電陶瓷片時(shí),時(shí)間不能太長(zhǎng)以免燙壞壓電陶瓷片的鍍銀層。由于壓電陶瓷片的資料比較

15、少，為了確定使用該傳感器能夠?qū)崿F(xiàn)本次設(shè)計(jì)的目5 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)的，先要對(duì)其進(jìn)行實(shí)驗(yàn)，來確定它的輸出電壓是否符合要求。由于只需要 4mv-5mv左右的電壓輸出，就可以實(shí)現(xiàn)設(shè)計(jì)要求。由試驗(yàn)，可以得知壓電陶瓷片可以實(shí)現(xiàn)我們所要達(dá)到的目標(biāo)。 整體電路分析經(jīng)實(shí)驗(yàn)可知,采用 GaAs 紅外發(fā)光二極管作為光源時(shí)，可基本抑制由呼吸運(yùn)動(dòng)造成的脈搏波曲線的漂移。脈搏波檢測(cè)以光電檢測(cè)技術(shù)為基礎(chǔ)，因此受周圍雜散光、暗電流等各種干擾影響較大，為了克服這一問題本系統(tǒng)采用脈沖振幅光調(diào)制技術(shù)。脈沖調(diào)制傳送的是調(diào)制信號(hào)的采樣值，只要采樣頻率奈奎斯特采樣頻率，則可由采樣脈沖來恢復(fù)原信號(hào)，而不會(huì)導(dǎo)致失真。系統(tǒng)

16、對(duì)紅外二極管的驅(qū)動(dòng)脈沖信號(hào)的頻率選定為工頻整數(shù)倍 400Hz 以降低工頻干擾，脈沖載波由 ADuC841 內(nèi)部 16 位數(shù)模轉(zhuǎn)換器產(chǎn)生。為了保證紅外發(fā)光二極管的光源穩(wěn)定，本文采用運(yùn)放 op495 和 NPN 型三極管作為恒流源電路向發(fā)光二極管提供穩(wěn)定的工作電流。光敏二極管的特性是將光信號(hào)轉(zhuǎn)換為電流，而隨后的 A/D 轉(zhuǎn)換電路是以電壓為檢測(cè)對(duì)象。因此，接收電路中應(yīng)采用電流電壓變換電路，將電流信號(hào)轉(zhuǎn)換為電壓信號(hào)。運(yùn)算放大器與電阻 R 形成電流電壓變換電路，如圖 4-2 所示。（圖中 S_GND 為信號(hào)地，運(yùn)算放大器工作正負(fù)電源為 5V、0V，為避免信號(hào)丟失，將信號(hào)抬高至VS_GND=1V）電路輸出

17、電壓。由于光電脈搏波屬于緩慢變化的微弱生理信號(hào)，信噪比低，極易受到環(huán)境噪聲和肢體運(yùn)動(dòng)的干擾。傳統(tǒng)的光電脈搏波信號(hào)檢測(cè)電路都采用高增益放大器，以獲得較高的檢測(cè)靈敏度，這種設(shè)計(jì)思路導(dǎo)致了檢測(cè)信號(hào)動(dòng)態(tài)范圍縮小，在受到運(yùn)動(dòng)干擾時(shí)，將導(dǎo)致由于干擾信號(hào)而帶來的光電脈搏波信號(hào)檢測(cè)的飽和失真。本系統(tǒng)采用過采樣技術(shù)，通過對(duì)信號(hào)的高速采樣來提高采樣精度，相當(dāng)于用高分辨率的 ADC 對(duì)信號(hào)進(jìn)行模數(shù)轉(zhuǎn)換，達(dá)到了提高信噪比并改善動(dòng)態(tài)范圍的效果。因此對(duì)經(jīng)過光電轉(zhuǎn)換后的信號(hào)進(jìn)行模數(shù)轉(zhuǎn)換而不需要任何信號(hào)調(diào)理（放大和濾波）電路。所謂過采樣技術(shù)是指以遠(yuǎn)遠(yuǎn)高于奈奎斯特 (Nyquist)采樣頻率的頻率對(duì)模擬信號(hào)進(jìn)行采樣的方法。由信

18、號(hào)采樣量化理論可知，若輸入信號(hào)的最小幅度大于量化器的量化電平，并且輸入信號(hào)的幅度隨機(jī)分布，則量化噪聲的總功率是一個(gè)常數(shù)，在0fs2 的頻帶范圍內(nèi)均勻分布。因此量化噪聲電平與采樣頻率成反比，如果提高采樣頻率，則可以降低量化噪聲電平，而由于基帶是固定不變的，因而減少了基帶范圍內(nèi)的噪聲功率，提高了信噪比，從而提高分辨率，并且采樣頻率每提高 4 倍，6 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)則信噪比提高 4 倍，相當(dāng)于 A/DC 的分辨率提高 1 位。濾波器為一個(gè)數(shù)字低通濾波器，主要是濾除采樣信號(hào)頻帶以外的高頻量化噪聲，并維持信號(hào)頻帶以內(nèi)的信號(hào)基本不變，抽取是將采樣得到的高速低分辨率的數(shù)字信號(hào)的抽樣頻率

19、降至奈奎斯特采樣頻率，進(jìn)而完成高分辨率數(shù)字信號(hào)的重構(gòu)，抗混疊主要是濾除降低取樣頻率后可能出現(xiàn)的混疊噪聲。數(shù)字濾波和抽取均通過軟件來實(shí)現(xiàn)，配置靈活。傳感器主要由紅外線發(fā)射二極管和接收二極管組成，測(cè)量的原理如下：將手指放在紅外線發(fā)射二極管和接收二極管中間，隨著心臟的跳動(dòng)，由于手指放在光的傳遞路徑中，血管中血液飽和程度的變化將引起光的強(qiáng)度發(fā)生變化，因此和心跳的節(jié)拍相對(duì)應(yīng)，紅外接收二極管的電流也跟著改變，這就導(dǎo)致紅外接收二極管輸出脈沖信號(hào)。脈沖信號(hào)由 F1F3、R3R5、C1、C2 等組成的低通放大器進(jìn)行放大，再經(jīng)由 F4、R6、R7、C3 組成的放大器進(jìn)一步放大，其輸出信號(hào)送給由 F5、F6、RP1

20、、R8 等組成的施密特觸發(fā)器進(jìn)行整形后輸出，輸出的脈沖信號(hào)作為單片機(jī)的外部中斷信號(hào)。可變電阻 RP1 用來調(diào)整施密特觸發(fā)器的閥值電壓，從而調(diào)整電路的靈敏度。AT89C2051、X1、R10、C5 等組成單片機(jī)電路，單片機(jī)電路對(duì) P3.2 輸入的脈沖信號(hào)進(jìn)行計(jì)算處理后把結(jié)果送到數(shù)碼管顯示，發(fā)光二極管 VD3 作脈搏測(cè)量狀態(tài)顯示，脈搏每跳動(dòng)一次發(fā)光二極管就點(diǎn)亮一次，數(shù)碼管 DS1DS3、VT1VT3、R12R21 等組成數(shù)碼顯示電路。本機(jī) P3.3-P3.5 口作三個(gè)數(shù)碼管的動(dòng)態(tài)掃描位驅(qū)動(dòng)碼輸出，通過三極管驅(qū)動(dòng)數(shù)碼管，P1.0-P1.6 口作數(shù)碼顯示七段筆劃字形碼的輸出，用以驅(qū)動(dòng)數(shù)碼管的各字段。原

21、文：Pulse transducer and circuit design7 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)Pulse has 2600 years of clinical practice, is the essence of the four diagnostic methods of traditional Chinese medicine. Pulse in traditional Chinese medicine, Western medicine has a very important significance. The Qiemo skills in traditiona

22、l Chinese pulse diagnosis is difficult to grasp and apply the doctors subjective factors, along with the development of science and technology, PVdF (polyvinylidene fluoride) piezoelectric film developed to determine the different pulse instrument the objectiveof the pulse, the sensitive part of the

23、 design of the pulse instrument sensor finger.This article from the perspective of the analog pulse diagnosis, the development of PVdF piezoelectric volume to obtain a large output power. Because of the change of unit-body thin film sensors, and applied to the pulse instrument. Plot the maximum outp

24、ut power is proportional to the electromechanical coupling coefficient and able to withstand thequantitative has become the inevitable trend of Chinese medicine diagnosis. Decades, thestate selected PVdF piezoelectric film, because it follows several advantages:First,film light and flexible, easy pr

25、eparation and human tissue impedance couplingcan be close to the skin, without distortion of the pulse signal through the film. In addition, the film is similar to human skin, you can create a biomimetic tactile sensor. The piezoelectric constant (d33 = 20 pC / N), the inotropic easy to study, but t

26、he development of the situation, most of the sensor can not be simulated in the sensitivity.10 times higher thanthe quartz crystal, the piezoelectric voltage output constant Qiemo take three, floating,three diagnostic methods, g = 174 is the highest of all the piezoelectric. Detection pulse signal d

27、epends mainly on the pressure calibration, the applicability is not good enough.Then,mechanical quality factor low, damping, low density, with broadband featuresto address the frequency characteristics of the pulse signal. If not depolarization in the very high alternating electric field.PVdF membra

28、ne flexibility and its thickness direction of the stretchingvibration of the resonant frequency is high, making a wide range of flat frequency. PVdF membrane above advantages, according to Chinese medicine Qiemo model, we developed a three-sen8 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)sor, three square sheet made by the P

29、VdF film transducer, an area equivalent to the forcethe Qiemo when pulp area in the piezoelectric film bipolar charge generated steam the aluminum electrode and leads to the wire, flexible organic plastic film packaging made of acircular substrate, mounted on a table to bring. Taking into account th

30、e patients signs, young and old, and other factors, the three transducer independently corresponds to the vertical and horizontal adjustment by floating an inch three parts, and can bring in the table.Strap-beam measurements in the wrist, and the doctor finger corresponding to enlarge three transduc

31、ers can. The doctor can feel through the thin slices pulse fluctuations. Floating, mode pulse process can artificially control the intensity, do vary from person to person to overcome the pressure of the past cylinder transducer calibration taken floating inadequate. When a periodic pulse pressure t

32、ransducer, mechanical energy converted to electricity.The pulse spectrum analysis shows that 99% of the energy in the pulse spectrum isconcentrated below 10 Hz, the highest frequency of no more than 40 Hz. Tune to achievecommunication with the computer. PVdF piezoelectric film transducer is sensitiv

33、e components in this design, is also designed one of the key links of the role of simulation in which the pressure sensation can, will the pulse pressure of the weak low-frequency signal conversion into electrical signals. Set of pre-charge amplifier role there are two: First, withthe transducer imp

34、edance matching, high-impedance input into a low impedance output;second is the weak charge into a voltage signal and zoom. In order to improve the measurement accuracy and sensitivity, pre-amplifier circuit using a linear correction of the charge amplifier to lower the lower limit frequency, elimin

35、ating the cable distribution of feed-forward capacitor.Capacitance on the sensitivity of the impact of the design of the small sensor size. The first low-pass filter circuit formed by R1 and C1, the cutoff frequency of about 1000 Hz, so that the higher harmonic of the pulse signal through the pulse

36、signal reflected pathological feature information to get the full reservation. While theupper limit cut-off frequency and the time constant circuit (formed by C2 and R2) will decisively influence the distortion of the pulse waveform. If the circuit time constant is selected too small, will cause a9

37、脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)serious low-frequency component of the signal attenuation and phase shift. The experiments show that when the time sufficient to ensure that the pulse wave of low frequency components without distortion. Voltage amplifier, the charge amplifier output voltage signalamplification. An

38、d provide different gain. According to our experience, set the upper cut-off frequency of 100Hz. Power frequency notch filter link in order to filter out the mains50HZ interference.Capacitor tantalum capacitor should be selected for the compensation capacitor, hardware power frequency notch and soft

39、ware filtering and measures taken to the city electrical noise, experimental results show that the use of digital filtering techniques, the inhibitory effect of frequency interference signals better electromagnetic signal suppression has mainly taken two ways, one signal line shield is designed for

40、fourth-order Butterworth low-pass filter cutoff frequency of 100 Hz. Jitter noise for the human body mainly through the software filter to filter out, mainly using the anti-pulse interference average filtering method. Sunplus, the algorithm implementation, the basic idea is thatthe 256 data measured

41、 as a queue, each time a new measurement, put the measurementsinto the tail, and remove the original team the first time data, such there is always 256, the latest data in the queue size, 256-by-comparison data to remove the maximum and minimum, and then calculate the average of 254 data. This filte

42、ring method for periodic interference of inhibition, but also occasionally filter out the pulse of human jitter generated interference. Found that, despite the persons body temperature is kept constant, but the wrist skin surface temperature of the outside temperature changes still, and the skin of

43、the wrist with the sensor surface, the temperature difference will have a great impact to the measurement requires the elimination of The temperature effect of the use of human pulse (1Hz) Thermal noise signal.As the body of the pulse signal has a low frequency, amplitude interference, instability,

44、randomness, and other characteristics, makes very strict requirements on the acquisition of the pulse signal amplifier design, especially the anti-interferencebecomes very important , need to design low-pass filter for filtering. Select amplifier from the gain, frequency response, input impedance, c

45、ommon-mode rejection ratio, noise, drift, several aspects to be taken into account. (1) anti-jamming10 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)First,power frequency the 50HZ interference and its harmonicsThe use of frequency 50HZ electricity electronic equipment devices can cause detection system will have a greater inte

46、rference, and its amplitude is about 50% of the pulse signal peak to peak, is the main source of interference; Then,EMG interferenceThe contraction of the muscle will produce microvolt potential, its amplitude is about 10% of the pulse signal peak to peak hold time is 50ms, the frequency range in 0H

47、Z10000HZ;Finaly,breathing caused by baseline drift and ECG amplitude variations Breathing caused by baseline drift sinus component (sinusoidal) can be seen as a respiratory frequency by adding the ECG signal, the amplitude and frequency of this sine componentsof change. Breathing caused by changes o

48、f the ECG signal amplitude can reach 15%. The baseline drift of the frequency from 0.15 0.3HZ. (2) low noise, low driftPulse amplifier, high gain, noise and drift are the two important parameters. Noise in the pulse amplifier running the electronic circuit of the inherent thermal noise and shot nois

49、e, these are the white noise, the amplitude for the normal distribution. In order to obtain a certain signal to noise ratio of the output signal, the amplifiers low noise performance, there are strict requirements. In addition, the temperature change will cause zero drift, drift limits the amplifier

50、s input range, the weak slowly varying signals can not be enlarged. The pulse signal has a very low frequency components to normal measurements, measures must be taken to limit the drift of the amplifier. Therefore, the amplifier should use low drift, high input impedance and high common mode reject

51、ion ratio of the integrated operational amplifier circuit.Other sensors First,piezoelectric sensorCurrently used disposable ECG electrodes, which is obtained by printing methods Ag / Agcl sensor. This sensor uses the method of separation then buckle sensitive areas, can significantly reduce the inte

52、rference due to human movement. Electrode The qualityof the collected ECG signal quality plays a vital role, using the electrode should be posted strong, can be tightly attached to the surface of the body, soft, absorbent, polarization voltage low, good electrical conductivity characteristics . Elec

53、ted electrode sensor, three electrodes were placed in the left and right hands and left leg, constitute the standard ECG.11 脈搏心率測(cè)量?jī)x中英文對(duì)照外文翻譯文獻(xiàn)Clinical order to unify and to facilitate the comparison of the pulse signal, the detected pulse signal, the connection of the electrode position, lead the am

54、plifier has a strict uniformprovisions.Currently on the market a new type of polymer piezoelectric material poly (vinylidene fluoride) piezoelectric sensor developed by its high sensitivity, good frequency range, simple structure, easy to use. When the finger front end by a slight pressure, you can

55、feel the finger front end in a relaxation of the blood pressure, this signal is extracted fromthe sensors into electrical signals, through refers pulse waveform detection, you can get the pulse of the human body signal.Secondly,photoelectric sensorBlood is a highly opaque liquid, light in the genera

56、l organization of penetrating than blood several times, whereby the characteristics of the photoelectric effect finger pulse sensor to pick up the pulse signal. Photodiode reverse bias, the reverse current with light intensity increases, the photoelectric effect characteristics, a linear relationshi

57、p in a certain light intensity within the photosensitive diode reverse current and light intensity. Thevolume of fingertip blood vessels and transmittance heart stroke changes will enable optical transistor diode receive a different light intensity, and the resulting photocurrent willbe a correspond

58、ing change. Commonly used in testing the pulse of photoelectric sensors is divided into infrared tube tube and infrared radiation.Infrared Emitting Diode, will hose clamp on the finger ends of finger blood concentration changes with the heart beating, infrared tube corresponding to the signalwill ch

59、ange accordingly, collecting the signal after amplification, filtering, and compare and other processing can be the ideal signal.Reflection type of infrared tube. The heart rate monitor on the market now commonly used in this sensor signal acquisition, because this infrared tube receiver and transmi

60、tter are on the same side of the finger, and therefore do not need to consider each person different fingers trouble. Received blood diffuse reflected light, this signal can accurately measure intravascular volume changes.Lastly,integrated sensorAt present, there are many types of integrated ECG sen