【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)(ti)脂(zhi)肪(fang)的(de)(de)含量，即脂(zhi)肪(fang)率的(de)(de)正確檢測方法(fa)是將(jiang)人(ren)體(ti)(ti)(ti)全部(bu)沒入水中，測出(chu)排水率（體(ti)(ti)(ti)積(ji)），再根(gen)據體(ti)(ti)(ti)重求出(chu)人(ren)體(ti)(ti)(ti)的(de)(de)比重，由(you)此推斷出(chu)人(ren)體(ti)(ti)(ti)的(de)(de)脂(zhi)肪(fang)率。但在日常情(qing)況下(xia)這(zhe)種方法(fa)不太現(xian)實(shi)。

人的身(shen)體(ti)(ti)(ti)含(han)水(shui)(shui)(shui)量約為(wei)70％，這些水(shui)(shui)(shui)份(fen)(fen)(fen)絕大部(bu)分存在(zai)于血液、瘦(shou)肉及內(nei)(nei)臟中，而(er)脂(zhi)(zhi)肪(fang)中含(han)水(shui)(shui)(shui)量極低。體(ti)(ti)(ti)內(nei)(nei)水(shui)(shui)(shui)份(fen)(fen)(fen)由于溶解(jie)有各(ge)(ge)種成分而(er)呈現低電(dian)(dian)(dian)阻(zu)(zu)，脂(zhi)(zhi)肪(fang)卻呈現高電(dian)(dian)(dian)阻(zu)(zu)，因(yin)而(er)人體(ti)(ti)(ti)中脂(zhi)(zhi)肪(fang)和水(shui)(shui)(shui)的比(bi)例影響到(dao)人體(ti)(ti)(ti)的電(dian)(dian)(dian)阻(zu)(zu)，如果考慮(lv)脂(zhi)(zhi)肪(fang)和水(shui)(shui)(shui)份(fen)(fen)(fen)的合成電(dian)(dian)(dian)阻(zu)(zu)，則脂(zhi)(zhi)肪(fang)多的人體(ti)(ti)(ti)電(dian)(dian)(dian)阻(zu)(zu)值就高。目(mu)前(qian)市售的各(ge)(ge)種人體(ti)(ti)(ti)脂(zhi)(zhi)肪(fang)測量儀幾乎都是(shi)以測量體(ti)(ti)(ti)電(dian)(dian)(dian)阻(zu)(zu)的方(fang)法來推測脂(zhi)(zhi)肪(fang)量，圖1為(wei)某產品的檢測方(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。

考慮到簡單易(yi)制，信號源采用(yong)了5kHz的正弦波，且不用(yong)單片機、數(shu)字顯示等，同時考慮到同一個人(ren)使用(yong)，只要了解自身(shen)(shen)體(ti)脂肪的變化(hua)情(qing)況就可以了，因而也(ye)未(wei)考慮人(ren)的的身(shen)(shen)高、體(ti)重(zhong)對檢測(ce)的影響。

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由T1、T2構成(cheng)(cheng)文氏電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)橋振蕩器，產(chan)生5KHz的(de)(de)正(zheng)弦波，經C5送到一只腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)上(shang)，另一只腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)負(fu)極(ji)相連，即人體(ti)兩支腳(jiao)(jiao)掌(zhang)間的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻與(yu)信(xin)號(hao)(hao)(hao)源(yuan)并聯。由于(yu)人體(ti)兩腳(jiao)(jiao)間電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻一般在(zai)數百kΩ以上(shang)，故其后(hou)(hou)的(de)(de)檢測電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)輸(shu)入采(cai)用(yong)了(le)高輸(shu)入阻抗的(de)(de)射極(ji)跟隨器T3；把T3輸(shu)出(chu)的(de)(de)信(xin)號(hao)(hao)(hao)經二極(ji)管(guan)整流取出(chu)與(yu)體(ti)脂肪率相關的(de)(de)直(zhi)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，再(zai)經一級射極(ji)跟隨器T4輸(shu)出(chu)到電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)表(biao)。由于(yu)輸(shu)入到檢測電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)信(xin)號(hao)(hao)(hao)很小(xiao)，而常規(gui)的(de)(de)二極(ji)管(guan)整流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)不適用(yong)于(yu)小(xiao)信(xin)號(hao)(hao)(hao)，故利(li)用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻R12給二極(ji)管(guan)加一偏置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，使二極(ji)管(guan)在(zai)無信(xin)號(hao)(hao)(hao)時(shi)仍有電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流通(tong)過，就可以增(zeng)加對小(xiao)信(xin)號(hao)(hao)(hao)的(de)(de)反應(ying)能力；與(yu)此(ci)對應(ying)，在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中(zhong)增(zeng)加了(le)由R15和VR2的(de)(de)調(diao)零電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)，以抵消前述偏置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)對測量(liang)結(jie)果(guo)(guo)的(de)(de)影響。由于(yu)是采(cai)用(yong)數字電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)表(biao)來測量(liang)檢測結(jie)果(guo)(guo)，故檢測電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)之后(hou)(hou)未設計放大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)。兩腳(jiao)(jiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)可用(yong)食品包(bao)裝鋁箔剪成(cheng)(cheng)四塊(kuai)(kuai)園片(pian)，每腳(jiao)(jiao)兩塊(kuai)(kuai)；取絕緣(yuan)板(ban)一塊(kuai)(kuai)，大小(xiao)與(yu)市售人體(ti)秤相當(dang)，在(zai)板(ban)上(shang)兩腳(jiao)(jiao)位置貼上(shang)與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)片(pian)大小(xiao)相同的(de)(de)雙面(mian)膠，從板(ban)下(xia)穿孔經過雙面(mian)膠穿入多股導線，并將(jiang)線頭分(fen)杈攤開在(zai)雙面(mian)膠表(biao)面(mian)，然后(hou)(hou)將(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)片(pian)壓(ya)(ya)(ya)緊(jin)在(zai)雙面(mian)膠上(shang)與(yu)導線緊(jin)密接觸，構成(cheng)(cheng)測量(liang)踏板(ban)。整機電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)用(yong)3V電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。

調整：

先確(que)認(ren)振(zhen)蕩(dang)器工作(zuo)正常。用音頻(pin)(pin)信號傳輸線從(cong)將C1輸出端及地端連接(jie)至立(li)體聲放大器，若振(zhen)蕩(dang)正常，可從(cong)喇叭聽到音頻(pin)(pin)聲；調整(zheng)VR1可聽出頻(pin)(pin)率的變(bian)化。

檢測電(dian)(dian)路應(ying)先調零(ling)，在(zai)檢測器(qi)輸(shu)出端接入(ru)數字萬(wan)用表(biao)(biao)的mV檔，在(zai)兩(liang)腳電(dian)(dian)極(ji)懸空的情(qing)況(kuang)下(xia)(xia)調整VR2，使電(dian)(dian)壓(ya)(ya)表(biao)(biao)指(zhi)示為0V。在(zai)上(shang)方(fang)兩(liang)電(dian)(dian)極(ji)片間串聯1M電(dian)(dian)阻，再(zai)將(jiang)兩(liang)手掌分別壓(ya)(ya)緊在(zai)上(shang)下(xia)(xia)兩(liang)電(dian)(dian)極(ji)板上(shang)，電(dian)(dian)壓(ya)(ya)表(biao)(biao)上(shang)應(ying)有(you)10~20mV的電(dian)(dian)壓(ya)(ya)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)極片位置，電(dian)壓表應有(you)一電(dian)壓值，如(ru)9mV，此(ci)值可作為日后測(ce)量脂肪率的參考值。一般，脂肪多的人(ren)電(dian)壓值高，瘦人(ren)電(dian)壓值低。