Buttons can be found everywhere. More than 10 billion mechanical buttons are sold every year. They can be found in consumer products such as smartphones, music players and TVs; home appliances such as washing machines and microwave ovens; and industrial products such as POS terminals, elevator controls and keypads. With such a universal presence of buttons, consumers want products with reliable and sleek user interfaces. Designs should not only be attractive but also robust to survive all conditions without collecting dirt. For this reason, capacitive buttons are replacing mechanical buttons in applications ranging from consumer to home appliances to industrial segments.