Factors affecting the accuracy of capacitive sensors - News - Global IC Trade Starts Here.

Capacitive sensors are widely used in precise measurements of angles, displacements, liquid levels, and other physical parameters. Their high sensitivity and accuracy make them a popular choice in many industrial and scientific applications. However, these benefits depend heavily on the sensor's design, material selection, and manufacturing process. To ensure reliable performance, it's important to understand and mitigate factors that can affect the accuracy of capacitive sensors.

1. Temperature Effects on Structural Dimensions

Changes in ambient temperature can cause expansion or contraction of the various components within a capacitive sensor. This thermal deformation may alter the spacing and alignment between the plates, leading to measurement errors. This issue is particularly significant in sensors designed to measure small gaps, where even minor dimensional changes can have a major impact on accuracy.

2. Temperature Influence on Dielectric Constant

The capacitance value of a sensor is directly proportional to the dielectric constant of the medium between the plates. If the dielectric material has a non-zero temperature coefficient, any temperature fluctuation will result in a change in capacitance, introducing a temperature-related error. This effect must be accounted for in high-precision applications.

3. Impact of Leakage Resistance

Capacitive sensors typically exhibit high capacitive reactance, especially at low excitation frequencies. When the leakage resistance between the two electrodes becomes comparable to the capacitive reactance, it can significantly reduce the overall sensitivity of the system. This shunting effect should be carefully considered during the design phase to maintain optimal performance.

4. Edge Effects and Parasitic Parameters

Edge effects occur due to the fringing electric fields at the edges of the capacitor plates, which complicate the calculation of capacitance and introduce non-linearities. These effects can reduce sensor sensitivity. One common method to minimize this is by adding a guard electrode, which should be maintained at the same potential as the main electrode to reduce unwanted field distortions.

In summary, while capacitive sensors offer excellent precision and sensitivity, their performance can be affected by several environmental and design-related factors. By addressing these issues through careful engineering and calibration, the reliability and accuracy of capacitive sensors can be greatly improved.