A Review on Capacitive Liquid Level Sensing Techniques

For contemporary communities, liquid-level management is of great significance. Liquid-level monitoring is utilized in a variety of industrial applications, including food processing, pharmaceutical manufacturing, chemical manufacturing, and water purification systems. Liquids are used in critical applications such as rocket fuel tanks, medical equipment, etc. These systems are prone to accidents caused by liquid leakages and liquid turbulence. Hence it is necessary to prevent such mishaps and save resources and additional costs which are incurred due to the same. This necessitates the design and development of liquid-level sensing systems that are used to detect and monitor the level of liquid. There are many techniques that can be used to sense the level of liquid-like mechanical floats, ultrasonic sensors, fibre optic cables, LASER systems, light dependant resistors, image processing, etc. Capacitive sensing has emerged as one of the booming technologies due to its simplistic design, responsiveness, accuracy, noise immunity, and easy deployment. It has evolved over time and is now a vital feature of a variety of products. This paper aims to review the existing capacitive sensing mechanisms and attempts to serve as a foundation for unexplored sensor geometries. A comparative analysis has been presented to assess the performance of the proposed techniques. Coplanar capacitive sensors are found to be effective over cylindrical capacitive sensors due to a decrease in size, simple design, and cost-effectiveness while maintaining the same accuracy, resolution and sensitivity.