Microfluidic control over topological states in channel-confined nematic flows

Simon Čopar (Author), Žiga Kos (Author), Tadej Emeršič (Author), Uroš Tkalec (Author)

Abstract

Compared to isotropic liquids, orientational order of nematic liquid crystals makes their rheological properties more involved, and thus requires fine control of the flow parameters to govern the orientational patterns. In microfluidic channels with perpendicular surface alignment, nematics discontinuously transition from perpendicular structure at low flow rates to flow-aligned structure at high flow rates. Here we show how precise tuning of the driving pressure can be used to stabilize and manipulate a previously unresearched topologically protected chiral intermediate state which arises before the homeotropic to flow-aligned transition. We characterize the mechanisms underlying the transition and construct a phenomenological model to describe the critical behaviour and the phase diagram of the observed chiral flow state, and evaluate the effect of a forced symmetry breaking by introduction of a chiral dopant. Finally, we induce transitions on demand through channel geometry, application of laser tweezers, and careful control of the flow rate.

Keywords

nematski tekoči kristali;mikrofluidika;nematic liquid crystals;microfluidics;

Data

Language:	English
Year of publishing:	2020
Typology:	1.01 - Original Scientific Article
Organization:	UL FMF - Faculty of Mathematics and Physics
UDC:	532.5
COBISS:	3400804
ISSN:	2041-1723
Views:	236
Downloads:	70
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary keywords:	nematski tekoči kristali;mikrofluidika;
Type (COBISS):	Article
Pages:	10 str.
Volume:	ǂVol. ǂ11
Issue:	ǂart. no. ǂ59
Chronology:	Jan. 2020
DOI:	10.1038/s41467-019-13789-9
ID:	13184876