Valveless pumping at low Reynolds numbers

TL;DR

This paper investigates valveless pumping at low Reynolds numbers using a series of oscillating pumps with phase shifts, demonstrating optimized phase configurations that outperform traditional peristaltic waves for microfluidic applications.

Contribution

It introduces a valveless pumping system driven by phase shifts rather than geometry, providing optimal phase configurations for maximum net flow.

Findings

Optimal phase shifts increase net flow by 25% over traditional methods.

Experimental and theoretical results show very good agreement.

Provides design principles for more efficient microfluidic pumps.

Abstract

Pumping at low Reynolds number is a ubiquitously encountered feature, both in biological organisms and engineered devices. Generating net flow requires the presence of an asymmetry in the system, which traditionally comes from geometric flow rectifiers. Here, we study a valveless system of $N$ oscillating pumps in series, where the asymmetry comes not from the geometry but from time, that is the phase shifts between the pumps. Experimental and theoretical results are in very good agreement. We provide the optimal phase shifts leading to the maximal net flow in the continuous $N\rightarrow \infty$ limit, larger by 25\% than that of a traditional peristaltic sinusoidal wave. Our results pave the way for the design of more efficient microfluidic pumps.