Self capacitance is the coupling of one plate of a capacitor to virtual ground. Just as with mutual capacitance, the self capacitance of the plate changes when a finger is near the plate. This change in self capacitance can be used to determine the distance to the finger. Self capacitance is often used in button, slider, and wheel (BSW) sensors. While it is possible to build a touch sensor using self capacitance, there are several drawbacks.