A diaphragm assembly for a mass flow controller is disclosed. The diaphragm assembly includes an aperture, side walls extending from the aperture and disposed about a central axis, the side walls including multiple convolutions, and a poppet including an interior surface facing the aperture and exterior sealing surface. At least a portion of the diaphragm assembly moveable extends and retracts within a control valve cavity of the mass flow controller. A push rod extending from the interior surface of the poppet moves, responsive to an actuator of the mass flow controller, to enable the exterior sealing surface of the poppet to open and close a flow path through the control valve cavity.