Parasitic influences in a capacitive transducer behavior

The most common parasitic effects involved in a capacitive measurement process are the fringing phenomenon, the error due to unparallel armatures, the capillarity phenomenon, the temperature and humidity influence and the electrical parasitic capacitances induced by the PCB connection traces. The main purpose of this article is to evaluate and extract the total value of those undesired effects from the capacitance measured value, to obtain the correct capacitance value. By combining a mathematical approach with the measurement procedures, the parasitic capacitances were deducted.