Wholesale China OEM Capacity Sensor Manufacturer

Definition

Capacity sensor is an instrument that reflects the transformation of other quantities in terms of capacitance. It is mainly composed of upper and lower electrodes, insulators and substrates. Under the action of pressure, the film will produce certain deformation, and the distance between the upper and lower layers will change, resulting in the change of capacitance, but the capacitance does not change linearly with the change of distance between electrodes. It also needs the measuring circuit to make certain nonlinear compensation for the output capacitance.

Classification

Divided by sensor type

• Touch sensor: including display device and input device

• Motion sensor: including accelerometer, gyroscope and magnetic sensor

• Position sensor: including displacement sensor and proximity sensor

• Other sensors: including pressure sensors, displacement sensors, liquid level sensors

Divided by principle

Capacity sensors are generally composed of two parallel electrodes. Air is used as the medium between the two electrodes. Without considering the edge effect, the capacitance can be expressed as C=εS/d, where ε means between the two electrodes The dielectric constant of the medium (that is, air), S represents the area covered by the two electrodes, and d represents the distance between the two electrodes. Capacitance is affected by these three parameters. Any change in any one parameter will change the capacitance. Therefore, capacity sensors are classified into three types:

• Medium change type (change in ε and therefore change in C)

• Area change type (change in S and change in C)

• Pole pitch change type (change in d and change in C)

Features

The capacity sensor needs to convert the measured mechanical quantity into voltage or current for amplification and processing. Under some conditions, these mechanical quantities change very slowly and the variation range is very small. The measurement should have high resolution. It is difficult for other sensors to meet the requirements of high resolution, while the resolution of some capacitance micrometers is 0.01μm. The maximum range is 100±5μm. Therefore, it is generally appropriate to use capacity sensors for detection. This kind of sensors have the following outstanding advantages:

?High impedance and low power, so the required input force is very small and the input energy is also very low.

Because the electrostatic attraction between the plates with electrodes is very small (about 10-5n), the capacity sensor requires very little input energy, so it is especially suitable to solve the measurement problems with low input energy, such as measuring very low pressure, force, small acceleration and displacement. It can be very sensitive, have very high resolution and feel 0.001μM or less.

?Good temperature stability.

The capacitance of the sensor is generally independent of the electrode material, which is conducive to the selection of materials with low temperature coefficient, and has little impact on the stability because of its very small heating.

?It has simple structure and strong adaptability. The object to be tested can be conductor or semiconductor, and can work in harsh environment.

The capacity sensor is simple in structure, easy to manufacture and can be made very small to realize some special measurements; It can work in harsh environments such as high and low temperature, strong radiation and strong magnetic field, and can also measure magnetic workpieces.

?Good dynamic response.

Due to the small electrostatic attraction between the plates and the small and thin movable part, it has high natural frequency and short dynamic response time. It can work at a frequency of several MHz. It is especially suitable for dynamic measurement, such as measuring vibration, instantaneous pressure, etc.

?Non contact measurement can be realized with average effect.

For example, non-contact measurement of vibration or eccentricity of rotating shaft, radial clearance of small ball bearing, etc. When using non-contact measurement, capacity sensor has average effect, which can reduce the influence of working surface roughness on measurement.

Ningbo Technic Lighting Co., Ltd.is one of the leading wholesale capacity sensor supplier&manufacturer, china oem capacity sensor factory, welcome to contact us.

Wholesale China OEM Capacity Sensor Manufacturer