The same sensor film can also be used as an actuator. Changes in thickness can be induced by applying a voltage on the film; compression and expansion of the film depends on the polarity of the voltage, and it occurs when both the outer surfaces of the film either attract or repel from each other. The attractive force between the surfaces while the film is uncharged is given by the equation:
x</big>
where C is the capacitance of the film and x is the film's thickness.