A pump includes an outer body; and a wall within said outer body. The outer body and the wall define a pumping cavity and an excitation cavity within the outer body. An excitable medium is contained within the excitation cavity. An excitation source is coupled to said excitable medium. This excitation source is operable to excite the excitable medium and create a standing wave therein. The standing wave acts through the wall to pump said fluid through said pumping cavity. Advantageously, the excitable medium is isolated from the pumped fluid by the wall.