A Review on the Interdigital Capacitors and Their Application in Different Sensors Based on the Liquid Dielectric

Compared to the other sensors, capacitive one exhibits many advantages such as linear measurement capability, excellent sensitivity, easy-to-use principles and ease of manufacturing. There is no friction in these types of sensors, thus temperature, humidity, and mechanical disturbances don’t affect their performance. Due to the growing demand for the integrated on-chip electronic systems and need for the sensor downscaling, interdigital capacitor type of the sensors has become increasingly popular. Interdigital capacitors )IDC( are fabricated on an insulating substrate. Electrodes of the IDCs are located on the same plate, which are connected to the ground or terminal voltage. The electrical field lines are closed through the substrate and dielectric material, which is placed on the electrodes. Moreover, based on the number of fingers and their geometrical specifications, capacitance of the IDCs varies. Sensitivity and capacitance of the interdigital capacitors are relatively higher in comparison with the other capacitors. Advantages of the IDCs make them a proper option for using in the sensors. These capacitors are also used in the chemical and biological sensors and in the telecommunications. In this study, a review on the capacitive sensors based on the IDCs and liquid dielectric has been accomplished.