Design ofCapacitive Sensor forConcentration Measurement
Witsarut Sriratana · 2006
Thispaper presents theanalysis ofideal equivalent circuit ofthedeveloped concentration sensor probe for chemical solutions byregarding toreasonable costs andreliability ofdevice. Thedesigned sensor probe consists of2 parallel electrode plates that arecoated byNylon with0.4mm thick andmounted together byResin with 2.5mm ofgap (0.09 times greater thanelectrode width). Anycapacity changes will becompared withtheelectric circuit that is obtained fromtheGoodWill R-L-Cstandard instrument, modelCTR,atthefrequency extending from1OOHz to2kHz. Fromtheexperiments, itwasfound that thesensor designed forEthyl Alcohol solution within concentration of500to 9500 and10%concentration interval, atroomtemperature of23OCandfrequency of100Hz,canprovide theresults withhighlinearity aswell ashigh resolution ofcapacity change whichis2pFper1%ofconcentration.