Optofluidic modulator based on peristaltic nematogen microflows

Cuennet, J. G.; Vasdekis, Andreas E.; Sio, Luciano De; Psaltis, Demetri

doi:10.1038/nphoton.2011.18

Cited by 101 publications

(72 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Simplicity of the phenomenon that does not require pumps nor even electrodes to produce dramatic optical and mechanical changes suggests that it might find applications in sensors, photonics, lab-on-a-chip, microand optofluidics. All these fields started to explore benefits offered by LC as a functional microfluidic and optofluidic medium [168][169][170][171][172][173] . …”

Section: Thermal Expansionmentioning

confidence: 99%

Transport of particles in liquid crystals

2014

View full text Add to dashboard Cite

show abstract

Section: Thermal Expansionmentioning

confidence: 99%

Transport of particles in liquid crystals

2014

View full text Add to dashboard Cite

show abstract

“…In the more recent past, microfluidics was starting to be used as a tool to generate liquid crystal droplets [30][31][32], to study their wonderful properties [33][34][35][36], and to investigate confinement and motion of topological defects [37][38][39][40], and potential applications [41]. However, the possibility to use the available microfluidic techniques for studying the fundamental behaviour of liquid crystal flows within minute confinements was never explored.…”

Section: Motivationmentioning

confidence: 99%

“…It is only very recently that experiments on backflow dynamics in microfluidic setups are being carried out: reporting on flow induced transitions [42,43], effects of molecular pretilt at confining surfaces [44], nematic textures in untreated channels (see (1) on the publication list), and electrically or mechanically modulated microflows [41,232].…”

Section: Nematic Flow In a Homeotropic Microchannelmentioning

confidence: 99%

Nematic Liquid Crystals and Nematic Colloids in Microfluidic Environment

Sengupta

Herminghaus

Bahr

2011

Molecular Crystals and Liquid Crystals

View full text Add to dashboard Cite

Where the mind is without fear and the head is held high;Where knowledge is free;Where the world has not been broken up into fragments by narrow domestic walls;Where words come out from the depth of truth;Where tireless striving stretches its arms towards perfection;Where the clear stream of reason has not lost its way into the dreary desert sand of dead habit;Where the mind is led forward by thee into ever-widening thought and actionInto that heaven of freedom, my Father, let my country awake.Rabindranath Tagore (1861Tagore ( -1941 To my parents, my brother, and all the sacrifices they made for me AbstractThe doctoral thesis presented here is one of the first systematic attempts to unravel the wonderful world of liquid crystals within microfluidic confinements, typically channels with dimensions of tens of micrometers. The present work is based on experiments with a roomtemperature nematic liquid crystal, 5CB, and its colloidal dispersions within microfluidic devices of rectangular cross-section, fabricated using standard techniques of soft lithography. To begin with, a combination of physical and chemical methods was employed to create well defined boundary conditions for investigating the flow experiments. The walls of the microchannels were functionalized to induce different kinds of surface anchoring of the 5CB molecules: degenerate planar, uniform planar, and homeotropic surface anchoring. Channels possessing composite anchoring conditions (hybrid) were additionally fabricated, e. g. homeotropic and uniform planar anchoring within the same channel. On filling the microchannels with 5CB in the isotropic phase, different equilibrium configurations of the nematic director resulted, as the sample cooled down to nematic phase. For a given surface anchoring, the equilibrium director configuration varied also with the channel aspect ratio. The static director field within the channel registered the initial conditions for the flow experiments. The static and i ii dynamic experiments have been analyzed using a combination of polarization, and confocal fluorescence microscopy techniques, along with particle tracking method for measuring the flow speeds. Additionally, dual-focus fluorescence correlation spectroscopy is introduced as a generic velocimetry tool for liquid crystal flows.The flow of nematic liquid crystals is inherently complex due to the coupling between the flow and the nematic director. The presence of the four confining walls and the nature of surface anchoring on them complicate the flow-director interactions further. In microchannels possessing degenerate planar anchoring, four different flow-induced defect textures were identified with increasing Ericksen number: π-walls, disclination lines pinned to the channel walls, disclination lines with one pinned and one freely suspended end, and disclination loops freely flowing in a chaotic manner. However, such textures and sequence of defects were not observed for flows within channels with homogeneous anchoring.Using experiments and numerical modeling...

show abstract

“…The method of controlling the orientation of nematic liquid crystal director by an external electric field and thereby tuning the effective refractive index has found profound applications for liquid crystals in optical devices. [1][2][3][4][5] However, due to the very nature of the nematic phase, this liquid crystal phase is not ideal for all photonic device applications. Some of the major limitations associated with using liquid crystals in their nematic phase in photonic devices include, first, difficulty in obtaining control over the surface anchoring, second, in the nematic phase the director fluctuations result in strong scattering effect.…”

mentioning

confidence: 99%

“…The term 4 3 pNa avg is much smaller than 1, therefore, can be neglected. Thus, a decrease in the n avg as the temperature decreases in the DC phase indicates that there is a decrease in either the molecular density (N) or/and in the average molecular polarizability (a avg ) of the system on reducing the temperature.…”

mentioning

confidence: 99%

Electrically tunable refractive index in the dark conglomerate phase of a bent-core liquid crystal

Nagaraj

Görtz

Goodby

et al. 2014

Applied Physics Letters

View full text Add to dashboard Cite

Here we report an electrically tunable refractive index observed in an isotropic liquid crystal phase known as the dark conglomerate (DC) phase. This unusual change in the refractive index which has not been reported before in the DC phase of other bent-core liquid crystals occurs because of a series of electric-field-driven transformations that take place in the DC phase of the studied bent-core liquid crystal. These transformations give rise to a decrease in the refractive index of the system, when an electric field is applied across the device, and no change in the birefringence is seen during such behavior. The electro-optic phenomenon is described in detail and the possibility of exploiting this for a number of liquid crystal based device applications is discussed. V C 2014 AIP Publishing LLC.

show abstract

Optofluidic modulator based on peristaltic nematogen microflows

Cited by 101 publications

References 35 publications

Transport of particles in liquid crystals

Transport of particles in liquid crystals

Nematic Liquid Crystals and Nematic Colloids in Microfluidic Environment

Electrically tunable refractive index in the dark conglomerate phase of a bent-core liquid crystal

Contact Info

Product

Resources

About