【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(ti)(ti)脂(zhi)肪的(de)含量，即脂(zhi)肪率(lv)的(de)正確(que)檢測(ce)方(fang)法是將(jiang)人(ren)體(ti)(ti)全部沒(mei)入(ru)水中(zhong)，測(ce)出排水率(lv)（體(ti)(ti)積），再根據體(ti)(ti)重(zhong)求(qiu)出人(ren)體(ti)(ti)的(de)比重(zhong)，由此推斷出人(ren)體(ti)(ti)的(de)脂(zhi)肪率(lv)。但在(zai)日常情(qing)況下這種方(fang)法不太現(xian)實。

人的(de)身體(ti)含(han)水量(liang)約為70％，這(zhe)些水份(fen)(fen)絕(jue)大部分存(cun)在于血液、瘦肉及內臟中(zhong)(zhong)(zhong)，而脂(zhi)(zhi)肪中(zhong)(zhong)(zhong)含(han)水量(liang)極(ji)低(di)。體(ti)內水份(fen)(fen)由(you)于溶解有(you)各種成分而呈現低(di)電阻(zu)，脂(zhi)(zhi)肪卻(que)呈現高電阻(zu)，因而人體(ti)中(zhong)(zhong)(zhong)脂(zhi)(zhi)肪和水的(de)比(bi)例(li)影響到人體(ti)的(de)電阻(zu)，如果考慮脂(zhi)(zhi)肪和水份(fen)(fen)的(de)合成電阻(zu)，則脂(zhi)(zhi)肪多(duo)的(de)人體(ti)電阻(zu)值就高。目前市(shi)售的(de)各種人體(ti)脂(zhi)(zhi)肪測量(liang)儀幾(ji)乎都是以測量(liang)體(ti)電阻(zu)的(de)方法來推測脂(zhi)(zhi)肪量(liang)，圖1為某(mou)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(hao)源采用(yong)(yong)了(le)5kHz的(de)(de)正弦(xian)波(bo)，且(qie)不(bu)用(yong)(yong)單片機、數字顯示等，同時考慮到同一個人使(shi)用(yong)(yong)，只(zhi)要了(le)解(jie)自身體脂肪的(de)(de)變化情況就(jiu)可以(yi)了(le)，因(yin)而也未考慮人的(de)(de)的(de)(de)身高(gao)、體重對檢測的(de)(de)影(ying)響。

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由(you)T1、T2構(gou)成(cheng)文氏(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)橋振蕩器，產生5KHz的(de)(de)(de)正弦波(bo)，經(jing)C5送到(dao)一只腳(jiao)(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)上，另一只腳(jiao)(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)負極(ji)(ji)(ji)相連，即(ji)人體兩支腳(jiao)(jiao)(jiao)掌間的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻與(yu)信(xin)號源并(bing)聯。由(you)于(yu)人體兩腳(jiao)(jiao)(jiao)間電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻一般在(zai)數(shu)百kΩ以上，故其后(hou)的(de)(de)(de)檢(jian)測(ce)(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)輸(shu)入(ru)采用(yong)了高輸(shu)入(ru)阻抗的(de)(de)(de)射極(ji)(ji)(ji)跟(gen)隨(sui)器T3；把T3輸(shu)出的(de)(de)(de)信(xin)號經(jing)二(er)極(ji)(ji)(ji)管整流取出與(yu)體脂肪率相關的(de)(de)(de)直(zhi)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，再經(jing)一級射極(ji)(ji)(ji)跟(gen)隨(sui)器T4輸(shu)出到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)。由(you)于(yu)輸(shu)入(ru)到(dao)檢(jian)測(ce)(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)(de)信(xin)號很小，而常規的(de)(de)(de)二(er)極(ji)(ji)(ji)管整流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)不適用(yong)于(yu)小信(xin)號，故利用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻R12給二(er)極(ji)(ji)(ji)管加(jia)(jia)一偏置(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，使二(er)極(ji)(ji)(ji)管在(zai)無信(xin)號時仍有(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流通過，就可以增加(jia)(jia)對(dui)小信(xin)號的(de)(de)(de)反應能力；與(yu)此(ci)對(dui)應，在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中增加(jia)(jia)了由(you)R15和VR2的(de)(de)(de)調零電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，以抵(di)消前(qian)述偏置(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)對(dui)測(ce)(ce)量(liang)結果(guo)的(de)(de)(de)影響(xiang)。由(you)于(yu)是(shi)采用(yong)數(shu)字(zi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)表(biao)來測(ce)(ce)量(liang)檢(jian)測(ce)(ce)結果(guo)，故檢(jian)測(ce)(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)之后(hou)未設計放大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)。兩腳(jiao)(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)可用(yong)食品包(bao)裝鋁(lv)箔剪成(cheng)四塊園片(pian)，每腳(jiao)(jiao)(jiao)兩塊；取絕緣(yuan)板一塊，大小與(yu)市售(shou)人體秤相當(dang)，在(zai)板上兩腳(jiao)(jiao)(jiao)位置(zhi)(zhi)貼上與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)片(pian)大小相同的(de)(de)(de)雙(shuang)面膠(jiao)(jiao)，從板下穿孔經(jing)過雙(shuang)面膠(jiao)(jiao)穿入(ru)多股(gu)導(dao)線(xian)，并(bing)將(jiang)線(xian)頭分杈攤開在(zai)雙(shuang)面膠(jiao)(jiao)表(biao)面，然后(hou)將(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)片(pian)壓(ya)緊(jin)在(zai)雙(shuang)面膠(jiao)(jiao)上與(yu)導(dao)線(xian)緊(jin)密接觸(chu)，構(gou)成(cheng)測(ce)(ce)量(liang)踏(ta)板。整機(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)用(yong)3V電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。

調整：

先(xian)確認振蕩(dang)器(qi)工作正常(chang)。用音(yin)頻信號傳輸線從將C1輸出(chu)端及(ji)地端連接至立體聲放大(da)器(qi)，若振蕩(dang)正常(chang)，可從喇叭聽到音(yin)頻聲；調整VR1可聽出(chu)頻率的變化。

檢測電(dian)(dian)(dian)路應先調零，在(zai)(zai)檢測器(qi)輸(shu)出(chu)端接入數字萬用表(biao)的(de)mV檔，在(zai)(zai)兩腳(jiao)電(dian)(dian)(dian)極(ji)(ji)懸空的(de)情(qing)況下調整VR2，使電(dian)(dian)(dian)壓(ya)表(biao)指(zhi)示(shi)為0V。在(zai)(zai)上方兩電(dian)(dian)(dian)極(ji)(ji)片間串聯1M電(dian)(dian)(dian)阻(zu)，再將兩手掌分(fen)別壓(ya)緊在(zai)(zai)上下兩電(dian)(dian)(dian)極(ji)(ji)板上，電(dian)(dian)(dian)壓(ya)表(biao)上應有10~20mV的(de)電(dian)(dian)(dian)壓(ya)指(zhi)示(shi)。

脂肪測量儀實際使用時，雙腳赤腳站在(zai)兩腳電(dian)極片位置，電(dian)壓表(biao)應(ying)有(you)一電(dian)壓值，如9mV，此值可作為(wei)日后(hou)測量(liang)脂肪率的參考值。一般，脂肪多(duo)的人(ren)電(dian)壓值高，瘦人(ren)電(dian)壓值低。