SUP-pH-5041 / เซ็นเซอร์วัดค่าพีเอช glass pH sensor SUP-pH-5041 glass pH sensor used in PH measurement is also called primary cell. The primary battery is a system whose function is to convert chemical energy into electrical energy. The voltage of this battery is called electromotive force (EMF). This electromotive force (EMF) consists of two half-cells.