Output of a valveless Liebau pump with biologically relevant vessel properties and compression frequencies

Abstract

Liebau pump is a tubular, non-peristaltic, pulsatile pump capable of creating unidirectional flow in the absence of valves. It requires asymmetrical positioning of the pincher relative to the attachment sites of its elastic segment to the rest of the circuit. Biological feasibility of such valveless pumps remains a hotly debated topic. To test the feasibility of the Liebau-based pumping in vessels with biologically relevant properties we quantified the output of Liebau pumps with their compliant segments made of a silicone rubber that mimicked the Young modulus of soft tissues. The lengths, the inner diameters, thicknesses of the tested compliant segments ranged from 1 to 5 cm, 3 to 8 mm and 0.3 to 1 mm, respectively. The compliant segment of the setup was compressed at 0.5–2.5 Hz frequencies using a 3.5-mm-wide rectangular piston. A nearest-neighbor tracking algorithm was used to track movements of 0.5-mm carbon particles within the system. The viscosity of the aqueous solution was varied by increased percentage of glycerin. Measurements yielded quantitative relationships between viscosity, frequency of compression and the net flowrate. The use of the Liebau principle of valveless pumping in conjunction with physiologically sized vessel and contraction frequencies yields flowrates comparable to peristaltic pumps of the same dimensions. We conclude that the data confirm physiological feasibility of Liebau-based pumping and warrant further testing of its mechanism using excised biological conduits or tissue engineered components. Such biomimetic pumps can serve as energy-efficient flow generators in microdevices or to study the function of embryonic heart during its normal development or in diseased states.

Building Valveless Impedance Pumps From Biological Components: Progress and Challenges

“…It has been argued that for such a difference to be maximal, the system has to be near its resonant frequency (Hickerson et al, 2005;Hickerson and Gharib, 2006). Yet many experimental studies, including our own work (Davtyan and Sarvazyan, 2021), observed significant flow rates at frequencies that are far below the estimated natural frequency (F n ) of the compliant segment. Let us consider the concept of F n in more detail.…”

“…In cases when solutions that mimic blood viscosity were used, the W o values further declined. This was the case in our own experiments that tested the performance of the Liebau pump with physiologically relevant vessel dimensions, viscosity, and compression frequencies (Davtyan and Sarvazyan, 2021).…”

“…These included inclusion of bends (Hiermeier and Männer, 2017), insertion of cavities (Kozlovsky et al, 2015), use of tapered connectors (Lee et al, 2017), or asymmetric arrangement of resistances between the two sides of the compliant tube (Wen and Chang, 2009). Due to its complexity and dependence on many variables, the pumping mechanism proposed by Liebau remains the subject of interest across a wide range of disciplines, including physiology, engineering, physics, and biomedical research (Hickerson et al, 2005;Rinderknecht et al, 2005;Hickerson and Gharib, 2006;Manopoulos et al, 2006Manopoulos et al, , 2020Bringley et al, 2008;Timmermann and Ottesen, 2009;Rosenfeld and Avrahami, 2010;Meier, 2011;Lee et al, 2013;Kozlovsky et al, 2016;Zislin and Rosenfeld, 2018;Li et al, 2019;Davtyan and Sarvazyan, 2021).…”

Acoustofluidics

“…However, by enlisting the finite amplitude deformation of the boundary with the propagation of the acoustic wave through the fluid bulk, a new form of acoustic streaming in confined media-acoustogeometric streaming-has been discovered in which the non-linear coupling between the motion of the boundary and the acoustic wave drives rapid fluid flow in a channel and against adverse pressures exceeding 1 MPa (Zhang et al, 2021a), far superior to classic streaming. Though reminiscent of peristaltic pumping and the Liebau pump mechanism (Davtyan and Sarvazyan, 2021), in fact the mechanism relies on acoustic wave propagation in the fluid, unlike these schemes. It is also sufficient to drive rapid fluid flows in nanochannels and to transport, split, combine, and even mix 20 to 200 fL droplets within (Zhang et al, 2021b).…”

Numerical Modelling of a Valveless Impedance Pump with Various Pinch Locations

“…Liebau suggested that viscosity, inertia and elasticity affected the parameters measured in the device. The pumping mechanism that was proposed by Liebau [12] is still the subject of interest across a wide range of disciplines, including physiology, engineering, physics, and biomedical research, due to the complexity of the mechanism and the fact that it is dependent on a large number of variables [13]. Liebau conducted the initial research on the phenomena of valveless pumping to comprehend the mechanism behind the blood circulatory system [14].…”