Multiplexing, switching and testing devices and methods using fluid pressure

A fluid pressure actuated device for establishing electrical contact includes a first side and a second side each defining a respective cavity. A respective flexible membrane is positioned across each cavity. Each membrane has an outer side that carries an electrically conducting contactor. The contactors are electrically connected to a conducting connector that extends at least partially through the device. Each flexible membrane extends and withdraws moving the associated electrically conducting contactor in opposing directions when fluid pressure is increased and decreased in the associated cavity. Each membrane may have an undulating shape by including concentric frustum portions that narrow in opposite directions. The contacts may have neutral positions that are internal relative to outer surfaces of the device until fluid pressure is increased in the respective cavities causing extension by movement of the membranes.