【人體脂肪測量儀】脂肪電子體重稱靠譜嗎 如何自制脂肪測量儀

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脂肪電子體重稱靠譜嗎

僅僅體重并不代表健康，人們越來越擔心自己體內的脂肪，因而各種人體脂肪測量儀產品出現在商場。

人(ren)體脂(zhi)肪(fang)的含量，即(ji)脂(zhi)肪(fang)率(lv)的正確檢測(ce)方(fang)法是將人(ren)體全部沒入水中，測(ce)出(chu)排水率(lv)（體積），再根據體重求出(chu)人(ren)體的比(bi)重，由此推斷出(chu)人(ren)體的脂(zhi)肪(fang)率(lv)。但(dan)在日(ri)常(chang)情況下(xia)這(zhe)種方(fang)法不太現實。

人(ren)的(de)身體(ti)含水(shui)量約為(wei)70％，這些水(shui)份絕大部分(fen)存(cun)在(zai)于(yu)血(xue)液、瘦(shou)肉及內臟中，而脂(zhi)(zhi)肪(fang)中含水(shui)量極低(di)。體(ti)內水(shui)份由于(yu)溶解有各種成分(fen)而呈(cheng)現低(di)電(dian)(dian)(dian)阻，脂(zhi)(zhi)肪(fang)卻呈(cheng)現高電(dian)(dian)(dian)阻，因而人(ren)體(ti)中脂(zhi)(zhi)肪(fang)和水(shui)的(de)比例影(ying)響到(dao)人(ren)體(ti)的(de)電(dian)(dian)(dian)阻，如果考(kao)慮脂(zhi)(zhi)肪(fang)和水(shui)份的(de)合成電(dian)(dian)(dian)阻，則脂(zhi)(zhi)肪(fang)多的(de)人(ren)體(ti)電(dian)(dian)(dian)阻值就高。目前市售的(de)各種人(ren)體(ti)脂(zhi)(zhi)肪(fang)測(ce)量儀幾乎都是以測(ce)量體(ti)電(dian)(dian)(dian)阻的(de)方(fang)法來推(tui)測(ce)脂(zhi)(zhi)肪(fang)量，圖(tu)1為(wei)某產(chan)品的(de)檢(jian)測(ce)方(fang)法。

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如何自制脂肪測量儀

下面介紹一款可自制的簡易人體脂肪測量儀。

考慮到簡單(dan)易制，信號源采用(yong)(yong)了5kHz的(de)(de)(de)正(zheng)弦波，且不用(yong)(yong)單(dan)片機(ji)、數(shu)字顯示等，同(tong)時考慮到同(tong)一個(ge)人使用(yong)(yong)，只要了解(jie)自身體(ti)脂肪的(de)(de)(de)變化情況就可以了，因而也未(wei)考慮人的(de)(de)(de)的(de)(de)(de)身高、體(ti)重對檢(jian)測的(de)(de)(de)影響。

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由(you)T1、T2構(gou)成(cheng)文氏電(dian)(dian)(dian)(dian)(dian)橋振蕩器，產生5KHz的(de)(de)(de)(de)(de)正(zheng)弦波，經(jing)C5送到(dao)一只(zhi)腳電(dian)(dian)(dian)(dian)(dian)極(ji)上，另一只(zhi)腳電(dian)(dian)(dian)(dian)(dian)極(ji)與(yu)(yu)(yu)(yu)電(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)(de)(de)負極(ji)相(xiang)連，即(ji)人體(ti)兩(liang)(liang)支腳掌(zhang)間(jian)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)阻與(yu)(yu)(yu)(yu)信號(hao)源并聯。由(you)于人體(ti)兩(liang)(liang)腳間(jian)電(dian)(dian)(dian)(dian)(dian)阻一般在數百kΩ以(yi)上，故其(qi)后(hou)的(de)(de)(de)(de)(de)檢(jian)測(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)輸(shu)入采用(yong)(yong)了高輸(shu)入阻抗的(de)(de)(de)(de)(de)射極(ji)跟隨(sui)器T3；把(ba)T3輸(shu)出(chu)(chu)的(de)(de)(de)(de)(de)信號(hao)經(jing)二(er)極(ji)管(guan)整(zheng)(zheng)流(liu)(liu)(liu)取出(chu)(chu)與(yu)(yu)(yu)(yu)體(ti)脂肪率相(xiang)關的(de)(de)(de)(de)(de)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，再經(jing)一級射極(ji)跟隨(sui)器T4輸(shu)出(chu)(chu)到(dao)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)表(biao)。由(you)于輸(shu)入到(dao)檢(jian)測(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)(de)(de)(de)信號(hao)很小(xiao)(xiao)，而常規的(de)(de)(de)(de)(de)二(er)極(ji)管(guan)整(zheng)(zheng)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)不適(shi)用(yong)(yong)于小(xiao)(xiao)信號(hao)，故利用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)阻R12給二(er)極(ji)管(guan)加一偏置(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，使(shi)二(er)極(ji)管(guan)在無(wu)信號(hao)時仍有電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)通過(guo)，就可以(yi)增加對小(xiao)(xiao)信號(hao)的(de)(de)(de)(de)(de)反(fan)應能力；與(yu)(yu)(yu)(yu)此對應，在電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中增加了由(you)R15和VR2的(de)(de)(de)(de)(de)調零電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)，以(yi)抵消前述偏置(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)對測(ce)(ce)(ce)量結果的(de)(de)(de)(de)(de)影響。由(you)于是采用(yong)(yong)數字電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)表(biao)來測(ce)(ce)(ce)量檢(jian)測(ce)(ce)(ce)結果，故檢(jian)測(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)之后(hou)未設計(ji)放(fang)大(da)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)。兩(liang)(liang)腳電(dian)(dian)(dian)(dian)(dian)極(ji)可用(yong)(yong)食品包裝(zhuang)鋁箔剪成(cheng)四塊(kuai)園片，每腳兩(liang)(liang)塊(kuai)；取絕緣板一塊(kuai)，大(da)小(xiao)(xiao)與(yu)(yu)(yu)(yu)市售人體(ti)秤相(xiang)當，在板上兩(liang)(liang)腳位(wei)置(zhi)(zhi)貼上與(yu)(yu)(yu)(yu)電(dian)(dian)(dian)(dian)(dian)極(ji)片大(da)小(xiao)(xiao)相(xiang)同的(de)(de)(de)(de)(de)雙(shuang)面(mian)膠(jiao)(jiao)，從板下穿孔經(jing)過(guo)雙(shuang)面(mian)膠(jiao)(jiao)穿入多股導線，并將線頭分杈攤開在雙(shuang)面(mian)膠(jiao)(jiao)表(biao)面(mian)，然后(hou)將電(dian)(dian)(dian)(dian)(dian)極(ji)片壓(ya)(ya)緊在雙(shuang)面(mian)膠(jiao)(jiao)上與(yu)(yu)(yu)(yu)導線緊密(mi)接(jie)觸，構(gou)成(cheng)測(ce)(ce)(ce)量踏(ta)板。整(zheng)(zheng)機(ji)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)用(yong)(yong)3V電(dian)(dian)(dian)(dian)(dian)池供(gong)電(dian)(dian)(dian)(dian)(dian)。

調整：

先確認振蕩器(qi)工作正常(chang)。用(yong)音頻(pin)(pin)信號(hao)傳輸線(xian)從將C1輸出(chu)端及地端連接至立體聲放(fang)大器(qi)，若(ruo)振蕩正常(chang)，可從喇叭聽(ting)到(dao)音頻(pin)(pin)聲；調整(zheng)VR1可聽(ting)出(chu)頻(pin)(pin)率(lv)的變化。

檢測(ce)(ce)電(dian)(dian)(dian)(dian)路(lu)應先(xian)調零，在(zai)檢測(ce)(ce)器(qi)輸出端接入數字萬用表的(de)mV檔(dang)，在(zai)兩(liang)腳電(dian)(dian)(dian)(dian)極懸空(kong)的(de)情況下調整VR2，使電(dian)(dian)(dian)(dian)壓(ya)表指示(shi)為0V。在(zai)上(shang)方兩(liang)電(dian)(dian)(dian)(dian)極片間串(chuan)聯1M電(dian)(dian)(dian)(dian)阻，再將(jiang)兩(liang)手(shou)掌分別壓(ya)緊在(zai)上(shang)下兩(liang)電(dian)(dian)(dian)(dian)極板上(shang)，電(dian)(dian)(dian)(dian)壓(ya)表上(shang)應有10~20mV的(de)電(dian)(dian)(dian)(dian)壓(ya)指示(shi)。

脂肪測量儀實際使(shi)用時，雙(shuang)腳赤腳站(zhan)在兩腳電極片位(wei)置(zhi)，電壓表(biao)應有一電壓值，如9mV，此(ci)值可作為日后測量脂肪(fang)率(lv)的參考值。一般(ban)，脂肪(fang)多的人(ren)電壓值高，瘦人(ren)電壓值低。