Capacitive load cells are based on the principle of change in capacitance when a force is applied by a symmetrical load cell. Capacitance is the ability of a system to store charge. If a classic parallel-plate method is used to build a capacitor, its ability to store charge is proportional to the area between the two plates and inversely proportional to the gap between the plates.
When a force or load or pressure is applied, the gap between the plates changes due to the deflection of the housing and causes a disproportionate change in capacitance, making the capacitance sensor extremely sensitive.
Capacitive sensors are much simpler to build than resistive load cells, and you can learn more by visiting the page describing "Why Capacitive Sensors?" In addition, by optimizing the starting gap and / or overlap area of the two boards, once the sensitivity and output signal can be changed to optimize it for various applications.
Capacitive technology can be used to measure clearance (proximity), humidity, tilt, force, torque, acceleration, fluid mass and many other physical parameters! This is a very flexible parameter that provides great sensitivity in a small package.