Longitudinal resonance wave pumping in compliant tubes: a bio-inspired approach

Impedance pump is a valveless pump that operates based on the principles of wave propagations and reflections. In its simplest form, an impedance pump is composed of a fluid-filled elastic tube connected to rigid tubes (reflection sites) and a pincher (wave generator). Previous studies have shown that aorta acts as an impedance pump where waves are created by the left ventricle (LV) pulsatile flow. Longitudinal stretching of the ascending aorta during the contraction of the LV is an important determinant of the aortic biodynamics and recent clinical studies have shown that this mechanism aids in LV early filling. To the best of our knowledge, the association between stretch-related dynamic mode of the ascending aorta and its impact on aortic hemodynamics has not been studied. Inspired by this natural aortic mechanism, we conducted a comprehensive analysis of the longitudinal model of the impedance pump. In this type of the impedance pump, waves are created by longitudinal stretching of the elastic wall. Our results indicate that stretch-related wave propagation and reflection in a fluid-filled compliant tube can create a pumping mechanism. Like other impedance pumps, both the direction and the magnitude of the net flow depend on the wave dynamic characteristics.