An array of movable elements is arranged on a substrate. Each element has a cavity and a movable member to move through the cavity. The pressure resistance of the elements varies, allowing actuation signals to be manipulated to activate elements with different pressure resistance at different levels...http://www.google.ca/patents/US20050195467?utm_source=gb-gplus-sharePatent US20050195467 - Altering temporal response of microelectromechanical elements
