Photo-Controllable Rotation of Cholesteric Double-Twist Cylinders

Bono, Shinji; Maruyama, Yuji; Nishiyama, Katsu; Tabe, Yuka

doi:10.1080/15421406.2019.1581703

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…Under uniform temperature gradient conditions, the striped texture of the Ch-LC droplets rotates unidirectionally with a constant angular velocity in the clockwise direction independently of the droplet position. We confirmed that the chirality inversion of the Ch-LC sample causes the rotational direction to reverse, which is consistent with previous reports on chiral inversion characteristics and cross-correlation 17 , 27 .…”

Section: Resultssupporting

confidence: 92%

“…The heat-driven rotation of the Ch-LC droplets dispersed in a corresponding isotropic (Iso) phase is a well-known example of such behavior 12 – 16 . Ch-LC droplets subjected to a uniform heat flux rotate unidirectionally, with a rotational direction and speed that depend on the Ch-LC chirality and the heat flux magnitude, respectively 17 . Note that the high conversion efficiency of the Ch-LC thermomechanical cross-correlation results because the droplets can directly convert heat flux into torque.…”

Section: Introductionmentioning

confidence: 99%

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Temperature gradient sensing mechanism using liquid crystal droplets with 0.1-mK-level detection accuracy and high spatial resolution

Bono

Konishi²

2022

Sci Rep

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We proposed the detection mechanism of the micro-levels of temperature gradient in a micro-electromechanical system using the unidirectional rotation of cholesteric-liquid crystal (Ch-LC) droplets. Ch-LC droplets in the presence of an isotropic phase subjected to a heat flux rotate with a speed proportional to the magnitude of the temperature gradient. We further quantified the temperature gradient-to-torque conversion efficiency to apply the thermomechanical cross-correlation to the detection of temperature gradient. Then, we observed the rotational behavior of Ch-LC droplets after introducing them onto model devices containing patterned Au thin-film electrodes. Direct electric current applied to these Au electrodes results in unidirectional rotation of the Ch-LC droplets in response to heat flux generated from the Au electrodes. By evaluating the possible temperature gradient detection resolution using Ch-LC droplet rotation, we show that Ch-LC droplets can achieve both high spatial resolution (~ 10 µm) and high detection accuracy (~ 0.1 mK/µm).

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Temperature gradient sensing mechanism using liquid crystal droplets with 0.1-mK-level detection accuracy and high spatial resolution

Bono

Konishi²

2022

Sci Rep

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“…To observe the position of the colloids and the director configuration inside the droplets simultaneously, we conducted POM observation with a white light source, in which a polarizer and an analyzer were set to form a 45° angle with each other. In a previous work, we confirmed that the amphiphilic PEO-PAzo considerably decreased the friction between glass substrates and Ch droplets, , so that the Ch droplets in this experiment are expected to be lubricated.…”

Section: Methodssupporting

confidence: 84%

Heat-Driven Rigid-Body Rotation of a Mixture of Cholesteric Liquid Crystal Droplets and Colloids

et al. 2020

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We show that cholesteric (Ch) liquid crystal droplets with cylindrically symmetric orientation dispersing in an isotropic (Iso) phase exhibited unidirectional rotation under a heat flux along the symmetry axis. By introducing colloidal particle adhesive to the Ch droplet surface, we traced the translational motion of the colloids and found that the colloids rotated unidirectionally around the center of each Ch droplet. The director configuration of the droplets was not distorted either spatially or temporally, while the colloids rotated constantly. The results suggest that the Ch droplets under the heat flux should rotate as a rigid body. Using this heat-driven rotation of the Ch droplets, we designed new geometries of various composites of Ch droplets and colloids and succeeded in driving intriguing complex dynamics.

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“…For this reason, the droplets melt during the measurements, which become very imprecise. A solution to solve this issue could be to change the surface treatment, for instance by us-UV[36]. It would also be interesting to make the dielectric anisotropy of the LC vanish, for instance by mixing MBBA with a small amount of 8CB (or 5CB[37]), to avoid texture changes under electric field.…”

mentioning

confidence: 99%

Role of an oscillatory electric field on the Lehmann rotation of cholesteric droplets

Oswald

2020

Eur. Phys. J. E

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This paper deals with the Lehmann rotation of banded cholesteric droplets subjected to a temperature gradient when they coexist with their own isotropic liquid. I show that their angular rotation velocity increases-in absolute value-when they are subjected to an additional AC electric field in the conducting regime. This velocity increase is correlated with a prolate distortion of the droplets and the probable presence of electrohydrodynamical toroidal circulation flows inside and outside the droplets. I propose that the coupling between these flows and the director field is responsible for the increase of the angular velocity of the texture. The origin of these flows is discussed qualitatively in the framework of the leaky dielectric model by taking into account the generation of charges both in the bulk via a Carr-Helfrich mechanism (Tarasov, Krekhow and Kramer model) and at the surface of the droplet (Taylor-Melcher model).

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Photo-Controllable Rotation of Cholesteric Double-Twist Cylinders

Cited by 6 publications

References 12 publications

Temperature gradient sensing mechanism using liquid crystal droplets with 0.1-mK-level detection accuracy and high spatial resolution

Temperature gradient sensing mechanism using liquid crystal droplets with 0.1-mK-level detection accuracy and high spatial resolution

Heat-Driven Rigid-Body Rotation of a Mixture of Cholesteric Liquid Crystal Droplets and Colloids

Role of an oscillatory electric field on the Lehmann rotation of cholesteric droplets

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