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Gautam B, Lintuvuori JS. Microswimmers Knead Nematics into Cholesterics. PHYSICAL REVIEW LETTERS 2024; 132:238301. [PMID: 38905647 DOI: 10.1103/physrevlett.132.238301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 04/30/2024] [Indexed: 06/23/2024]
Abstract
The hydrodynamic stresses created by active particles can destabilize orientational order present in the system. This is manifested, for example, by the appearance of a bend instability in active nematics or in quasi-two-dimensional living liquid crystals consisting of swimming bacteria in thin nematic films. Using large-scale hydrodynamics simulations, we study a system consisting of spherical microswimmers within a three-dimensional nematic liquid crystal. We observe a spontaneous chiral symmetry breaking, where the uniform nematic state is kneaded into a continuously twisting state, corresponding to a helical director configuration akin to a cholesteric liquid crystal. The transition arises from the hydrodynamic coupling between the liquid crystalline elasticity and the swimmer flow fields, leading to a twist-bend instability of the nematic order. It is observed for both pusher (extensile) and puller (contractile) swimmers. Further, we show that the liquid crystal director and particle trajectories are connected: in the cholesteric state the particle trajectories become helicoidal.
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Affiliation(s)
- Bhavesh Gautam
- Univ. Bordeaux, CNRS, LOMA, UMR 5798, F-33400 Talence, France
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Bezrukov A, Galeeva A, Krupin A, Galyametdinov Y. Molecular Orientation Behavior of Lyotropic Liquid Crystal-Carbon Dot Hybrids in Microfluidic Confinement. Int J Mol Sci 2024; 25:5520. [PMID: 38791556 PMCID: PMC11122583 DOI: 10.3390/ijms25105520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/02/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Lyotropic liquid crystals represent an important class of anisotropic colloid systems. Their integration with optically active nanoparticles can provide us with responsive luminescent media that offer new fundamental and applied solutions for biomedicine. This paper analyzes the molecular-level behavior of such composites represented by tetraethylene glycol monododecyl ether and nanoscale carbon dots in microfluidic channels. Microfluidic confinement allows for simultaneously applying multiple factors, such as flow dynamics, wall effects, and temperature, for the precise control of the molecular arrangement in such composites and their resulting optical properties. The microfluidic behavior of composites was characterized by a set of analytical and modeling tools such as polarized and fluorescent microscopy, dynamic light scattering, and fluorescent spectroscopy, as well as image processing in Matlab. The composites were shown to form tunable anisotropic intermolecular structures in microchannels with several levels of molecular ordering. A predominant lamellar structure of the composites was found to undergo additional ordering with respect to the microchannel axis and walls. Such an alignment was controlled by applying shear and temperature factors to the microfluidic environment. The revealed molecular behavior of the composite may contribute to the synthesis of hybrid organized media capable of polarized luminescence for on-chip diagnostics and biomimetics.
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Affiliation(s)
- Artem Bezrukov
- Department of Physical and Colloid Chemistry, Kazan National Research Technological University, 68 Karl Marx Str., 420015 Kazan, Russia; (A.G.); (A.K.); (Y.G.)
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Zhang Q, Wang W, Zhou S, Zhang R, Bischofberger I. Flow-induced periodic chiral structures in an achiral nematic liquid crystal. Nat Commun 2024; 15:7. [PMID: 38191525 PMCID: PMC10774319 DOI: 10.1038/s41467-023-43978-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 11/26/2023] [Indexed: 01/10/2024] Open
Abstract
Supramolecular chirality typically originates from either chiral molecular building blocks or external chiral stimuli. Generating chirality in achiral systems in the absence of a chiral input, however, is non-trivial and necessitates spontaneous mirror symmetry breaking. Achiral nematic lyotropic chromonic liquid crystals have been reported to break mirror symmetry under strong surface or geometric constraints. Here we describe a previously unrecognised mechanism for creating chiral structures by subjecting the material to a pressure-driven flow in a microfluidic cell. The chirality arises from a periodic double-twist configuration of the liquid crystal and manifests as a striking stripe pattern. We show that the mirror symmetry breaking is triggered at regions of flow-induced biaxial-splay configurations of the director field, which are unstable to small perturbations and evolve into lower energy structures. The simplicity of this unique pathway to mirror symmetry breaking can shed light on the requirements for forming macroscopic chiral structures.
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Affiliation(s)
- Qing Zhang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Weiqiang Wang
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Shuang Zhou
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Rui Zhang
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China.
| | - Irmgard Bischofberger
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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Ulaganathan V, Sengupta A. Spatio-temporal programming of lyotropic phase transition in nanoporous microfluidic confinements. J Colloid Interface Sci 2023; 649:302-312. [PMID: 37352561 DOI: 10.1016/j.jcis.2023.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 05/04/2023] [Accepted: 06/03/2023] [Indexed: 06/25/2023]
Abstract
HYPOTHESIS The nanoporous polydimethylsiloxane (PDMS) surfaces of a rectangular microfluidic channel, selectively uptakes water molecules, concentrating the solute molecules in an aqueous phase, that could drive phase transitions. Factors such as surface wettability, channel geometry, the surface-to-volume ratio, and surface topography of the confinements could play a key role in tuning the phase transitions spatio-temporally. EXPERIMENTS Using a lyotropic chromonic liquid crystal as model biological material, confined within nanoporous microfluidic environments, we study molecular assembly driven by nanoporous substrates. By combining timelapse polarized imaging, quantitative image processing, and a simple mathematical model, we analyze the phase transitions and construct a master diagram capturing the role of surface wettability, channel geometry and embedded topography on programmable lyotropic phase transitions. FINDINGS Intrinsic PDMS nanoporosity and confinement cross-section, together with the imposed wettability regulate the rate of the N-M phase transition; whereas the microfluidic geometry and embedded topography enable phase transition at targeted locations. We harness the emergent long-range order during N-M transition to actuate elasto-advective transport of embedded micro-cargo, demonstrating particle manipulation concepts governed by tunable phase transitions. Our results present a programmable physical route to material assembly in microfluidic environment, and offer a new paradigm for assembling genetic components, biological cargo, and minimal synthetic cells.
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Affiliation(s)
- Vamseekrishna Ulaganathan
- Physics of Living Matter Group, Department of Physics and Materials Science, University of Luxembourg, 162 A, Avenue de la Faïencerie, L-1511 Luxembourg City, Luxembourg
| | - Anupam Sengupta
- Physics of Living Matter Group, Department of Physics and Materials Science, University of Luxembourg, 162 A, Avenue de la Faïencerie, L-1511 Luxembourg City, Luxembourg.
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Zhang Q, Zhou S, Zhang R, Bischofberger I. Dendritic patterns from shear-enhanced anisotropy in nematic liquid crystals. SCIENCE ADVANCES 2023; 9:eabq6820. [PMID: 36638169 PMCID: PMC9839321 DOI: 10.1126/sciadv.abq6820] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Controlling the growth morphology of fluid instabilities is challenging because of their self-amplified and nonlinear growth. The viscous fingering instability, which arises when a less viscous fluid displaces a more viscous one, transitions from exhibiting dense-branching growth characterized by repeated tip splitting of the growing fingers to dendritic growth characterized by stable tips in the presence of anisotropy. We controllably induce such a morphology transition by shear-enhancing the anisotropy of nematic liquid crystal solutions. For fast enough flow induced by the finger growth, the intrinsic tumbling behavior of lyotropic chromonic liquid crystals can be suppressed, which results in a flow alignment of the material. This microscopic change in the director field occurs as the viscous torque from the shear flow becomes dominant over the elastic torque from the nematic potential and macroscopically enhances the liquid crystal anisotropy to induce the transition to dendritic growth.
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Affiliation(s)
- Qing Zhang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Shuang Zhou
- Department of Physics, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Rui Zhang
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Irmgard Bischofberger
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Palak, Parmar VRS, Chanda S, Bandyopadhyay R. Emergence of transient reverse fingers during radial displacement of a shear-thickening fluid. Colloids Surf A Physicochem Eng Asp 2023. [DOI: 10.1016/j.colsurfa.2023.130926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Ge B, Zhang Q, Zhang R, Lin JT, Tseng PH, Chang CW, Dong CY, Zhou R, Yaqoob Z, Bischofberger I, So PTC. Single-Shot Quantitative Polarization Imaging of Complex Birefringent Structure Dynamics. ACS PHOTONICS 2021; 8:3440-3447. [PMID: 37292495 PMCID: PMC10249439 DOI: 10.1021/acsphotonics.1c00788] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polarization light microscopes are powerful tools for probing molecular order and orientation in birefringent materials. While a number of polarization microscopy techniques are available to access steady-state properties of birefringent samples, quantitative measurements of the molecular orientation dynamics on the millisecond time scale have remained a challenge. We propose polarized shearing interference microscopy (PSIM), a single-shot quantitative polarization imaging method, for extracting the retardance and orientation angle of the laser beam transmitting through optically anisotropic specimens with complex structures. The measurement accuracy and imaging performance of PSIM are validated by imaging a birefringent resolution target and a bovine tendon specimen. We demonstrate that PSIM can quantify the dynamics of a flowing lyotropic chromonic liquid crystal in a microfluidic channel at an imaging speed of 506 frames per second (only limited by the camera frame rate), with a field-of-view of up to 350 × 350 μm2 and a diffraction-limit spatial resolution of ~2 μm. We envision that PSIM will find a broad range of applications in quantitative material characterization under dynamical conditions.
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Affiliation(s)
- Baoliang Ge
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Laser Biomedical Research Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Qing Zhang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Rui Zhang
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong 999077, China
| | - Jing-Tang Lin
- Department of Physics, National Taiwan University, Taipei 106 Taiwan, Republic of China
| | - Po-Hang Tseng
- Department of Physics, National Taiwan University, Taipei 106 Taiwan, Republic of China
| | - Che-Wei Chang
- Department of Physics, National Taiwan University, Taipei 106 Taiwan, Republic of China
| | - Chen-Yuan Dong
- Department of Physics, National Taiwan University, Taipei 106 Taiwan, Republic of China
| | - Renjie Zhou
- Department of Biomedical Engineering, The Chinese University of Hong Kong, New Territories, Hong Kong 999077, China
| | - Zahid Yaqoob
- Laser Biomedical Research Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Irmgard Bischofberger
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peter T C So
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Laser Biomedical Research Center and Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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