Liebau impedance pumping is a unique way of transporting fluid by simply compressing a flexible tube; no valves are needed. This work includes the design and implementation of a fully functioning, optically accessible Liebau pump with a visualization of the flow generated using refractive index matched particle image velocimetry (RIM-PIV).
Investigation into Liebau pumping is vital because of the potential role it plays in embryonic heart development. It is hypothesized that Liebau impedance pumping is the main driver of blood flow in the early-stage embryonic heart. At these stages of development, the embryonic heart is a straight tube, like that of a Liebau pump, without any of the valves or chambers seen in a fully developed heart. Therefore, Liebau impedance pumping could be a possible blood flow driver, however, very little work has gone into understanding Liebau pumps or their potential role in the embryonic heart.
Impedance is the natural resistance of a material to transferring a wave. A Liebau impedance pump is a flexible tube that is filled with fluid and connected to something with an impedance different from its own. By rhythmically compressing the flexible tube in a noncentral location, unidirectional flow can be created. The compression mechanism used in this design is a cam and follower mechanism, chosen for its ability to controllably pinch the tube, driving the flow.
In this work, RIM-PIV was used to visualize the flow within the Liebau pump. To use this technique, the flexible tube of the pump was cast out of polydimethylsiloxane (PDMS) to match its refractive index to that of the glycerin water solution that the pump is submerged in and that is flowing within the pump. The resulting RIM-PIV measurements, which are the first of their kind in a Liebau impedance pump, will contribute to the understanding of the velocity profile created within a Liebau pump and to answering the question of whether or not Liebau pumping is responsible for creating blood flow in the early stages of embryonic heart development.