A sensitive and linear pressure transducer
Mahfoozur Rehman, Vempati G. K. Murti · Journal of Physics E Scientific Instruments · 1981
The principle, construction and preliminary test results of a new capacitive pressure transducer are presented. The unit constructed may be used for the measurement of differential pressure in the medium and low ranges. The primary sensor is a U-tube manometer, comprised of two Teflon tubes filled with mercury. The two tubes are placed coaxially through the central spaces of two cylindrical cross-capacitors built on the same base. Due to the shielding effect of mercury in the U-tube, changes in the capacitance of the two cross capacitors occur whenever pressure is applied. These changes in capacitance are measured, employing an inductive voltage divider (IVD) in a transformer bridge set-up, in terms of the value of a standard capacitor. Besides its extremely high sensitivity and linearity, the scheme is considered capable of achieving a high order of accuracy and appears suitable for the calibration of other types of differential pressure gauges.