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

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Capacitive sensors are widely used in the precise measurement of angles, displacements, liquid levels, and other physical parameters. These sensors offer high sensitivity and accuracy, but their performance heavily depends on proper design, appropriate material selection, and advanced manufacturing techniques. However, there are several factors that can affect the accuracy of capacitive sensors, which should be carefully considered during system development.

Firstly, temperature changes can cause dimensional variations in the sensor’s structural components. As the ambient temperature fluctuates, the size and relative positions of the plates or electrodes may change, leading to unwanted temperature-induced errors. This is especially significant in sensors that measure small gaps, as even minor dimensional shifts can greatly impact the output signal.

Secondly, temperature also affects the dielectric constant of the medium between the sensor plates. Since capacitance is directly proportional to the dielectric constant, any variation in this value due to temperature changes will result in a corresponding shift in the measured capacitance, introducing inaccuracies into the readings.

Thirdly, leakage resistance can have a notable impact on sensor performance. Capacitive sensors typically exhibit high capacitive reactance, particularly at low excitation frequencies. When the leakage resistance between the two electrodes becomes comparable to the capacitive reactance, it can create a shunting effect, reducing the overall sensitivity of the system and degrading the sensor’s response.

Lastly, edge effects and parasitic capacitances can introduce nonlinearities and reduce sensitivity. These effects arise from electric field fringing at the edges of the capacitor plates. To mitigate these issues, a guard electrode is often added to the structure. The guard electrode should be maintained at the same potential as the main sensing electrode and ideally grounded to minimize interference and improve measurement accuracy.

In summary, while capacitive sensors provide excellent performance in many applications, careful attention must be given to environmental factors such as temperature, material properties, and electrical characteristics to ensure reliable and accurate measurements.