Activity-induced instability of phonons in 1D microfluidic crystals

Alan Cheng Hou Tsang, Michael Shelley, Eva Kanso

Research output: Contribution to journalArticle

Abstract

One-dimensional crystals of passively-driven particles in microfluidic channels exhibit collective vibrational modes reminiscent of acoustic 'phonons'. These phonons are induced by the long-range hydrodynamic interactions among the particles and are neutrally stable at the linear level. Here, we analyze the effect of particle activity-self-propulsion-on the emergence and stability of these phonons. We show that the direction of wave propagation in active crystals is sensitive to the intensity of the background flow. We also show that activity couples, at the linear level, transverse waves to the particles' rotational motion, inducing a new mode of instability that persists in the limit of large background flow, or, equivalently, vanishingly small activity. We then report a new phenomenon of phonons switching back and forth between two adjacent crystals in both passively-driven and active systems, similar in nature to the wave switching observed in quantum mechanics, optical communication, and density stratified fluids. These findings could have implications for the design of commercial microfluidic systems and the self-assembly of passive and active micro-particles into one-dimensional structures.

Original languageEnglish (US)
Pages (from-to)945-950
Number of pages6
JournalSoft Matter
Volume14
Issue number6
DOIs
StatePublished - Jan 1 2018

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Phonons
Microfluidics
phonons
Crystals
crystals
Density (optical)
Quantum theory
Optical communication
transverse waves
Self assembly
Wave propagation
Propulsion
optical density
propulsion
Hydrodynamics
Acoustics
optical communication
self assembly
quantum mechanics
wave propagation

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

Cite this

Activity-induced instability of phonons in 1D microfluidic crystals. / Tsang, Alan Cheng Hou; Shelley, Michael; Kanso, Eva.

In: Soft Matter, Vol. 14, No. 6, 01.01.2018, p. 945-950.

Research output: Contribution to journalArticle

Tsang, ACH, Shelley, M & Kanso, E 2018, 'Activity-induced instability of phonons in 1D microfluidic crystals', Soft Matter, vol. 14, no. 6, pp. 945-950. https://doi.org/10.1039/c7sm01335c
Tsang, Alan Cheng Hou ; Shelley, Michael ; Kanso, Eva. / Activity-induced instability of phonons in 1D microfluidic crystals. In: Soft Matter. 2018 ; Vol. 14, No. 6. pp. 945-950.
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