Methods of and systems for balancing the capacitance of a common series capacitive circuit in a semiconductor-based sensor, such as a humidity sensor, are described. Relative humidity sensors can provide measurements via a series capacitive circuit including a humidity-sensitive dielectric separating a common top plate and first and second bottom plates associated with a first and second capacitor, Cx1 and Cx2. For proper operation, the common top plate should be in capacitive balance. Capacitive balance can be achieved by creating voids within and/or along the common top plate of the sensor. A system for creating voids can include a precision cutting instrument, a measuring device for enabling the measurement of capacitance of at least one of the common series capacitive circuit, Cx1 and Cx2, and power provided from a voltage source.