Variable Capacitance Pressure Sensor

Capacitive pressure sensor having a substrate with a curved mesa us5792957a en 1993 07 24.

Variable capacitance pressure sensor. The capacitive pressure sensor operates on the principle that if the sensing diaphragm between two capacitor plates is deformed by a differential pressure an imbalance of capacitance will occur between itself and the two plates. A variable capacitance sensor is constructed with its capacitance plates connected at their center. A pressure sensor usually acts as a transducer. Which converts applied pressure into a current signal like 4 20ma.

Automotive systems laboratory inc. This imbalance is detected in a capacitance bridge circuit and converted to a d c. What is the capacitive pressure transducer. Capacitive pressure sensors with high linearity by optimizing electrode boundaries us6056079a en 1996 12 19.

The structure provides decreased thermal path lengths to reduce thermal effects. The capacitive transducer is used for measuring the displacement pressure and other physical quantities. For the purposes of this article such a signal is electrical. It is a passive transducer that means it requires external power for operation.

A pressure sensor is a device for pressure measurement of gases or liquids pressure is an expression of the force required to stop a fluid from expanding and is usually stated in terms of force per unit area. The capacitance pressure transmitter is a pressure measurement device. This is shown in figure where the movement of a. Stress relieving means are provided to eliminate hysteresis effects from the connecting structure.

An example of a capacitive pressure sensor is shown to the right. Endress hauser gmbh co. It generates a signal as a function of the pressure imposed. Output current of 4 to 20 ma.

The capacitive transducer or sensor is nothing but the capacitor with variable capacitance. Typically one electrode is a pressure sensitive diaphragm and the other is fixed. Viatran differential pressure transmitters make use of variable capacitance technology as do the viatran gage type and absolute pressure sensors. The advantages of this technology are obvious in measurement sensitivity at low pressure ranges.

Typical variable capacitance sensor cross section. The capacitive transducer comprises of two parallel metal plates that are separated by the material such as air which is called as the dielectric material. In the typical capacitor the distance between the two plates is fixed but in variable capacitance transducers the distance between the two plates. The capacitance of the capacitive transducer changes because of many reasons like overlapping of.

The conducting surfaces forming the capacitor are insulated from the central connection and each other.