【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)脂(zhi)(zhi)肪(fang)(fang)的含(han)量，即脂(zhi)(zhi)肪(fang)(fang)率的正確(que)檢(jian)測方法(fa)是將人(ren)(ren)體(ti)(ti)全(quan)部沒入水(shui)中，測出(chu)排水(shui)率（體(ti)(ti)積(ji)），再根據(ju)體(ti)(ti)重(zhong)求(qiu)出(chu)人(ren)(ren)體(ti)(ti)的比重(zhong)，由此推(tui)斷出(chu)人(ren)(ren)體(ti)(ti)的脂(zhi)(zhi)肪(fang)(fang)率。但(dan)在日(ri)常情況下這種(zhong)方法(fa)不太現實(shi)。

人(ren)(ren)的(de)身體(ti)含(han)水量約為70％，這些水份(fen)絕大部分存(cun)在于血液、瘦肉及內(nei)臟中(zhong)，而(er)脂(zhi)(zhi)肪(fang)中(zhong)含(han)水量極(ji)低(di)。體(ti)內(nei)水份(fen)由于溶(rong)解(jie)有各(ge)種(zhong)成分而(er)呈現(xian)低(di)電阻(zu)，脂(zhi)(zhi)肪(fang)卻呈現(xian)高(gao)電阻(zu)，因(yin)而(er)人(ren)(ren)體(ti)中(zhong)脂(zhi)(zhi)肪(fang)和水的(de)比例影響到人(ren)(ren)體(ti)的(de)電阻(zu)，如果考(kao)慮(lv)脂(zhi)(zhi)肪(fang)和水份(fen)的(de)合成電阻(zu)，則(ze)脂(zhi)(zhi)肪(fang)多的(de)人(ren)(ren)體(ti)電阻(zu)值就高(gao)。目前(qian)市售的(de)各(ge)種(zhong)人(ren)(ren)體(ti)脂(zhi)(zhi)肪(fang)測量儀幾乎都(dou)是(shi)以測量體(ti)電阻(zu)的(de)方法來(lai)推測脂(zhi)(zhi)肪(fang)量，圖1為某產品的(de)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。

考慮到簡單易制，信號源采用(yong)(yong)了(le)5kHz的正弦波，且不(bu)用(yong)(yong)單片機(ji)、數字顯(xian)示等，同時考慮到同一個人(ren)使用(yong)(yong)，只要了(le)解自身體(ti)脂肪的變化情況就(jiu)可以(yi)了(le)，因(yin)而(er)也未(wei)考慮人(ren)的的身高(gao)、體(ti)重(zhong)對檢測的影響(xiang)。

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由T1、T2構成(cheng)文氏電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)橋(qiao)振蕩器，產生5KHz的(de)(de)(de)正弦(xian)波，經(jing)(jing)C5送到(dao)一(yi)只腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)上(shang)(shang)，另(ling)一(yi)只腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)負極(ji)(ji)(ji)(ji)(ji)相(xiang)(xiang)連，即人體兩(liang)支(zhi)腳(jiao)(jiao)掌間(jian)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻與(yu)信號(hao)源并聯(lian)。由于(yu)人體兩(liang)腳(jiao)(jiao)間(jian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻一(yi)般在(zai)(zai)數百(bai)kΩ以(yi)上(shang)(shang)，故其后的(de)(de)(de)檢(jian)測(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)輸(shu)(shu)入(ru)采(cai)用了高(gao)輸(shu)(shu)入(ru)阻抗的(de)(de)(de)射(she)極(ji)(ji)(ji)(ji)(ji)跟隨器T3；把(ba)T3輸(shu)(shu)出(chu)的(de)(de)(de)信號(hao)經(jing)(jing)二極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)整(zheng)流(liu)取出(chu)與(yu)體脂肪率相(xiang)(xiang)關的(de)(de)(de)直流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，再經(jing)(jing)一(yi)級射(she)極(ji)(ji)(ji)(ji)(ji)跟隨器T4輸(shu)(shu)出(chu)到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)表。由于(yu)輸(shu)(shu)入(ru)到(dao)檢(jian)測(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)(de)信號(hao)很小(xiao)，而常規的(de)(de)(de)二極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)整(zheng)流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)不適用于(yu)小(xiao)信號(hao)，故利用電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻R12給二極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)加一(yi)偏置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，使二極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)在(zai)(zai)無信號(hao)時仍有電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)通過，就可以(yi)增加對小(xiao)信號(hao)的(de)(de)(de)反應能力；與(yu)此對應，在(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中增加了由R15和VR2的(de)(de)(de)調零電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)，以(yi)抵消前述偏置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)對測(ce)量結果(guo)的(de)(de)(de)影(ying)響。由于(yu)是(shi)采(cai)用數字電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)表來測(ce)量檢(jian)測(ce)結果(guo)，故檢(jian)測(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)之后未(wei)設計放大(da)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)。兩(liang)腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)可用食品包裝鋁箔剪(jian)成(cheng)四塊園片，每腳(jiao)(jiao)兩(liang)塊；取絕(jue)緣(yuan)板一(yi)塊，大(da)小(xiao)與(yu)市售人體秤(cheng)相(xiang)(xiang)當，在(zai)(zai)板上(shang)(shang)兩(liang)腳(jiao)(jiao)位置貼上(shang)(shang)與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)片大(da)小(xiao)相(xiang)(xiang)同的(de)(de)(de)雙面(mian)膠，從板下(xia)穿孔(kong)經(jing)(jing)過雙面(mian)膠穿入(ru)多股導線，并將線頭分杈攤開在(zai)(zai)雙面(mian)膠表面(mian)，然(ran)后將電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)片壓(ya)(ya)緊在(zai)(zai)雙面(mian)膠上(shang)(shang)與(yu)導線緊密接觸，構成(cheng)測(ce)量踏板。整(zheng)機電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)用3V電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。

調整：

先確認振蕩器(qi)工作正(zheng)常(chang)。用音頻信號傳輸(shu)線從(cong)將C1輸(shu)出(chu)端及地端連接至(zhi)立體聲放大器(qi)，若振蕩正(zheng)常(chang)，可(ke)從(cong)喇叭聽到音頻聲；調整VR1可(ke)聽出(chu)頻率的變(bian)化。

檢測(ce)電(dian)(dian)路應先(xian)調(diao)零，在(zai)檢測(ce)器輸出端接入數字萬用表(biao)(biao)的(de)(de)mV檔，在(zai)兩(liang)腳(jiao)電(dian)(dian)極(ji)(ji)懸空的(de)(de)情況下調(diao)整VR2，使電(dian)(dian)壓表(biao)(biao)指示(shi)(shi)為0V。在(zai)上(shang)方(fang)兩(liang)電(dian)(dian)極(ji)(ji)片間串聯(lian)1M電(dian)(dian)阻(zu)，再將(jiang)兩(liang)手掌(zhang)分別壓緊(jin)在(zai)上(shang)下兩(liang)電(dian)(dian)極(ji)(ji)板(ban)上(shang)，電(dian)(dian)壓表(biao)(biao)上(shang)應有10~20mV的(de)(de)電(dian)(dian)壓指示(shi)(shi)。

脂肪測量儀實際使用(yong)時(shi)，雙腳赤腳站在兩腳電(dian)極片位置，電(dian)壓表應有(you)一(yi)電(dian)壓值，如9mV，此值可作為日后測量脂肪率的參考值。一(yi)般，脂肪多的人電(dian)壓值高，瘦(shou)人電(dian)壓值低。