a microelectromechanical fluid ejection device configured for detecting a fault condition is provided . the device comprises a mechanical actuator , drive circuitry and a switch device . the actuator is displaceable upon receipt of an electrical current from the drive circuitry and the displacement causes ejection of fluid from an aperture in the device . the switch device determines an extent of displacement of the actuator and comprises a contact element positioned for contact with the actuator ; and processing circuitry for detecting when the actuator makes contact with the contact element .