Resonant pumping in a multilayer impedance pump
This paper introduces the concept of multilayer impedance pump, a novel pumping mechanism inspired by the embryonic heart structure. The pump is a composite two-layer fluid-filled elastic tube featuring a thick gelatinous internal. Pumping is based on the impedance pumping mechanism. In an impedance pump, elastic waves are generated upon external periodic compressions of the elastic tube. These waves propagate along the tube's walls, reflect at the tube's extremities, and drive the flow in a preferential direction. The originality in the multilayer impedance pump design relies on the use of the thick internal gelatinous layer to amplify the elastic waves responsible for the pumping. As a consequence, only small excitations are needed to produce significant flow. This fully coupled fluid-structure interaction problem is solved for the flow and the structure using the finite element method over a relevant range of frequencies of excitation. Results show that the multilayer impedance pump is a complex system that exhibits a resonant response. Flow output and inner wall motion are maximal when the pump is actuated at the resonant frequency. The wave interaction mechanism present in an impedance pump is described here in details for the case of a multilayer impedance pump. Using energy balance for the passive portion of the elastic tube, we show that the elastic tube itself works as a pump and that at resonance maximum energy transmission between the elastic tube and the fluid occurs. Finally, the pump is especially suitable for many biomedical applications.
©2008 American Institute of Physics. Received 22 August 2007; accepted 24 January 2008; published 28 February 2008.