【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)(ren)體(ti)(ti)(ti)脂(zhi)肪的含量，即脂(zhi)肪率的正確檢測方(fang)法(fa)是將人(ren)(ren)體(ti)(ti)(ti)全部沒入水(shui)中，測出(chu)排(pai)水(shui)率（體(ti)(ti)(ti)積(ji)），再(zai)根據體(ti)(ti)(ti)重(zhong)求(qiu)出(chu)人(ren)(ren)體(ti)(ti)(ti)的比重(zhong)，由(you)此推斷出(chu)人(ren)(ren)體(ti)(ti)(ti)的脂(zhi)肪率。但在日(ri)常情況(kuang)下(xia)這種方(fang)法(fa)不太現實。

人(ren)的身體(ti)含(han)水(shui)(shui)量約為(wei)70％，這些水(shui)(shui)份絕大部分(fen)存在于(yu)血(xue)液(ye)、瘦肉及(ji)內(nei)臟中(zhong)，而脂(zhi)(zhi)(zhi)肪(fang)(fang)中(zhong)含(han)水(shui)(shui)量極低(di)。體(ti)內(nei)水(shui)(shui)份由于(yu)溶(rong)解有各(ge)種(zhong)成(cheng)分(fen)而呈(cheng)現低(di)電(dian)(dian)(dian)阻(zu)，脂(zhi)(zhi)(zhi)肪(fang)(fang)卻呈(cheng)現高電(dian)(dian)(dian)阻(zu)，因而人(ren)體(ti)中(zhong)脂(zhi)(zhi)(zhi)肪(fang)(fang)和水(shui)(shui)的比例影(ying)響到人(ren)體(ti)的電(dian)(dian)(dian)阻(zu)，如果考慮(lv)脂(zhi)(zhi)(zhi)肪(fang)(fang)和水(shui)(shui)份的合成(cheng)電(dian)(dian)(dian)阻(zu)，則脂(zhi)(zhi)(zhi)肪(fang)(fang)多的人(ren)體(ti)電(dian)(dian)(dian)阻(zu)值(zhi)就高。目前市售的各(ge)種(zhong)人(ren)體(ti)脂(zhi)(zhi)(zhi)肪(fang)(fang)測量儀幾乎都是(shi)以測量體(ti)電(dian)(dian)(dian)阻(zu)的方法來推測脂(zhi)(zhi)(zhi)肪(fang)(fang)量，圖1為(wei)某產品(pin)的檢測方法。

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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(lv)到簡(jian)單(dan)(dan)易制，信號(hao)源采用了(le)5kHz的正弦波，且不用單(dan)(dan)片機、數字(zi)顯(xian)示等，同時(shi)考慮(lv)到同一個(ge)人(ren)(ren)使用，只要了(le)解自身體(ti)(ti)脂肪(fang)的變化情況就可以了(le)，因而(er)也(ye)未(wei)考慮(lv)人(ren)(ren)的的身高、體(ti)(ti)重對檢測(ce)的影響。

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由(you)T1、T2構(gou)成文氏電(dian)(dian)(dian)(dian)(dian)橋(qiao)振(zhen)蕩器，產生(sheng)5KHz的(de)(de)(de)正(zheng)弦波，經C5送到一(yi)只(zhi)腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)極上(shang)，另一(yi)只(zhi)腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)極與(yu)電(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)負極相(xiang)(xiang)連，即(ji)人體(ti)兩(liang)(liang)支腳(jiao)(jiao)掌間(jian)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)與(yu)信號源并(bing)聯。由(you)于人體(ti)兩(liang)(liang)腳(jiao)(jiao)間(jian)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)一(yi)般在(zai)(zai)數(shu)百kΩ以(yi)上(shang)，故(gu)其后的(de)(de)(de)檢(jian)測(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)路(lu)輸(shu)入采用(yong)了高輸(shu)入阻(zu)(zu)抗的(de)(de)(de)射(she)極跟隨(sui)器T3；把T3輸(shu)出的(de)(de)(de)信號經二極管(guan)整流取出與(yu)體(ti)脂肪(fang)率相(xiang)(xiang)關的(de)(de)(de)直流電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，再經一(yi)級射(she)極跟隨(sui)器T4輸(shu)出到電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)表。由(you)于輸(shu)入到檢(jian)測(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)(de)信號很小(xiao)(xiao)(xiao)，而常規的(de)(de)(de)二極管(guan)整流電(dian)(dian)(dian)(dian)(dian)路(lu)不適(shi)用(yong)于小(xiao)(xiao)(xiao)信號，故(gu)利用(yong)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)R12給二極管(guan)加(jia)一(yi)偏置電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，使二極管(guan)在(zai)(zai)無信號時仍有電(dian)(dian)(dian)(dian)(dian)流通過(guo)(guo)，就(jiu)可以(yi)增(zeng)加(jia)對小(xiao)(xiao)(xiao)信號的(de)(de)(de)反應能力；與(yu)此對應，在(zai)(zai)電(dian)(dian)(dian)(dian)(dian)路(lu)中增(zeng)加(jia)了由(you)R15和(he)VR2的(de)(de)(de)調零(ling)電(dian)(dian)(dian)(dian)(dian)路(lu)，以(yi)抵消(xiao)前述(shu)偏置電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)對測(ce)(ce)(ce)量結(jie)(jie)果的(de)(de)(de)影(ying)響。由(you)于是(shi)采用(yong)數(shu)字電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)表來測(ce)(ce)(ce)量檢(jian)測(ce)(ce)(ce)結(jie)(jie)果，故(gu)檢(jian)測(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)路(lu)之后未設計放大(da)(da)電(dian)(dian)(dian)(dian)(dian)路(lu)。兩(liang)(liang)腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)極可用(yong)食品包裝鋁箔剪成四塊園(yuan)片，每腳(jiao)(jiao)兩(liang)(liang)塊；取絕緣板(ban)一(yi)塊，大(da)(da)小(xiao)(xiao)(xiao)與(yu)市售人體(ti)秤相(xiang)(xiang)當(dang)，在(zai)(zai)板(ban)上(shang)兩(liang)(liang)腳(jiao)(jiao)位置貼上(shang)與(yu)電(dian)(dian)(dian)(dian)(dian)極片大(da)(da)小(xiao)(xiao)(xiao)相(xiang)(xiang)同的(de)(de)(de)雙(shuang)面膠(jiao)(jiao)，從(cong)板(ban)下穿孔(kong)經過(guo)(guo)雙(shuang)面膠(jiao)(jiao)穿入多(duo)股導(dao)線(xian)，并(bing)將線(xian)頭分杈(cha)攤開在(zai)(zai)雙(shuang)面膠(jiao)(jiao)表面，然(ran)后將電(dian)(dian)(dian)(dian)(dian)極片壓(ya)(ya)緊在(zai)(zai)雙(shuang)面膠(jiao)(jiao)上(shang)與(yu)導(dao)線(xian)緊密接觸，構(gou)成測(ce)(ce)(ce)量踏板(ban)。整機電(dian)(dian)(dian)(dian)(dian)路(lu)用(yong)3V電(dian)(dian)(dian)(dian)(dian)池供電(dian)(dian)(dian)(dian)(dian)。

調整：

先確認振蕩(dang)器工(gong)作正常(chang)。用(yong)音(yin)頻信號(hao)傳輸(shu)線從(cong)將C1輸(shu)出(chu)端及(ji)地端連接至(zhi)立體聲放(fang)大器，若振蕩(dang)正常(chang)，可從(cong)喇(la)叭聽到音(yin)頻聲；調整VR1可聽出(chu)頻率的變化。

檢測電(dian)路應(ying)先調零(ling)，在(zai)(zai)檢測器(qi)輸出(chu)端接入數(shu)字萬用(yong)表(biao)的(de)mV檔，在(zai)(zai)兩(liang)腳(jiao)電(dian)極(ji)懸(xuan)空的(de)情況(kuang)下(xia)調整VR2，使電(dian)壓表(biao)指(zhi)示為0V。在(zai)(zai)上(shang)方兩(liang)電(dian)極(ji)片間(jian)串聯1M電(dian)阻(zu)，再將兩(liang)手掌分別壓緊在(zai)(zai)上(shang)下(xia)兩(liang)電(dian)極(ji)板上(shang)，電(dian)壓表(biao)上(shang)應(ying)有10~20mV的(de)電(dian)壓指(zhi)示。

脂肪測量儀實際使用(yong)時，雙腳(jiao)赤腳(jiao)站在兩腳(jiao)電(dian)極片(pian)位置(zhi)，電(dian)壓(ya)表(biao)應有一電(dian)壓(ya)值(zhi)(zhi)，如(ru)9mV，此值(zhi)(zhi)可作為日(ri)后測量脂(zhi)肪(fang)率的參考值(zhi)(zhi)。一般，脂(zhi)肪(fang)多的人電(dian)壓(ya)值(zhi)(zhi)高，瘦人電(dian)壓(ya)值(zhi)(zhi)低。