Drop Traffic in Microfluidic Ladder Networks with Fore-Aft Structural Asymmetry

TL;DR

This study explores how fore-aft structural asymmetry in microfluidic ladder networks with slanted bypasses can control drop dynamics, enabling complex behaviors like contraction, expansion, and flipping, with potential for delay coding.

Contribution

It introduces the concept that structural asymmetry in microfluidic networks can be used to modulate drop spacing and enable non-linear delay transformations.

Findings

Asymmetry allows control over drop spacing behaviors.

Experiments confirm theoretical predictions.

Mixed bypasses enable non-linear delay coding.

Abstract

We investigate the dynamics of pairs of drops in microfluidic ladder networks with slanted bypasses, which break the fore-aft structural symmetry. Our analytical results indicate that unlike symmetric ladder networks, structural asymmetry introduced by a single slanted bypass can be used to modulate the relative drop spacing, enabling them to contract, synchronize, expand, or even flip at the ladder exit. Our experiments confirm all these behaviors predicted by theory. Numerical analysis further shows that while ladder networks containing several identical bypasses are limited to nearly linear transformation of input delay between drops, mixed combination of bypasses can cause significant non-linear transformation enabling coding and decoding of input delays.