Photocontrolled capacitive biosensor based on photoresponsive azobenzene-doped liquid crystals for label-free protein assay

Wang, Yi-Qiao; Wu, Po-Chang; Lee, Mon-Juan; Lee, Wei

doi:10.1016/j.molliq.2021.117908

Cited by 10 publications

(3 citation statements)

References 29 publications

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“…In particular, the pitch of a Ch mixture containing chiral molecules with photosensitive groups, such as azobenzene moieties, could be tuned by an exposure to light which causes trans-to-cis isomerization and thus changes molecular interactions responsible for the equilibrium 𝑝. [15][16][17][18] Imagine that an active droplet is placed in a Ch confined between two glass plates. One of these is rubbed to produce a unidirectional alignment along an axis 𝑥, for example; the second plate allows the director to glide on it.…”

Section: Introductionmentioning

confidence: 99%

Dynamic control of active droplets using light-responsive chiral liquid crystal environment

Lavrentovich,

Jiron,

Rajabi

et al. 2024

Preprint

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Microscopic active droplets are of interest since they can be used to transport matter from one point to another. The challenge is to control the trajectory. In this work, we demonstrate an approach to control the direction of active droplet propulsion by a photoresponsive cholesteric liquid crystal environment. The active droplet represents a water dispersion of bacterial B. subtilis microswimmers. When placed in a cholesteric, a surfactant-stabilized active droplet distorts the local director field, producing a point defect-hedgehog, which breaks the fore-aft symmetry. The chaotic motion of the bacteria inside the droplet is rectified into directional motion by the asymmetric director field outside the droplet. When the pitch of the cholesteric is altered by visible light irradiation, the asymmetry axis and thus the droplet trajectory realign along a new direction. Droplets realign counterclockwise on exposure to light of 535 nm, and clockwise on exposure to light of 450 nm, as dictated by the photoinduced change in the handedness of the cholesteric. The strategy allows for a non-contact dynamic control of active droplets trajectories and demonstrates the advantage of orientationally ordered media in control of active matter over their isotropic counterparts.

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Section: Introductionmentioning

confidence: 99%

Dynamic control of active droplets using light-responsive chiral liquid crystal environment

Lavrentovich,

Jiron,

Rajabi

et al. 2024

Preprint

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“…Various CLC materials and structures have thus been developed to implement tunable reflective colors in a varying degree of wavelength tunability by modulating the CLC pitch directly through temperature variations [ 1 , 2 ], light irradiation [ 3 , 4 , 5 ], and applied voltage [ 6 , 7 , 8 ], or indirectly through electrothermal [ 9 , 10 , 11 , 12 ], mechanical [ 13 , 14 ], and hydrodynamic [ 15 ] effects. Due to their uniqueness, CLCs have been extensively exploited or introduced for numerous applications, including in color filters [ 16 , 17 ], lasers [ 18 , 19 ], reflective displays [ 20 , 21 ], reflective polarizers [ 22 , 23 ], sensors [ 24 , 25 , 26 , 27 , 28 ], and smart windows [ 29 , 30 , 31 ]. However, as birefringence in CLCs is typically lower than 0.2 and only one of the two circularly polarized components of light can be reflected, a CLC bandgap is inherently limited to reflect unpolarized light colors within a narrow bandwidth with a reflectance R % less than 50%.…”

Section: Introductionmentioning

confidence: 99%

Bicolor Tuning and Hyper-Reflective Color Switching Based on Two Stacked Cholesteric Liquid Crystal Cells with Asymmetric Electrothermal Optical Responses

Tseng,

Wu,

Lee

2024

Molecules

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We propose a double-cell cholesteric liquid crystal (CLC) device composed of a left-handed (LH) CLC cell with a pair of sheet electrodes and a right-handed (RH) CLC cell with a tri-electrode configuration characterized by a sheet electrode on the top and an interdigitated electrode on the bottom substrates. Bi-reflected color tuning and hyper-reflective color switching are revealed from this cell stack via the electrothermal control of the central wavelengths of the LH- and RH-bandgaps by voltage-induced pseudo-dielectric heating. The two CLCs are thermally sensitive and exhibit overlapped bandgaps in the field-off state with nearly identical temperature dependence, resulting in a hyper-reflective color at 720 nm at 23.4 °C and 380 nm at 29.8 °C. Upon the application of 4 Vrms at 2 MHz across the stacked device to induce pseudo-dielectric heating, two reflective colors can be resolved due to asymmetrical temperature elevations. Accordingly, the difference in wavelength between the two colors increases with increasing voltage through a series cell connection, while maintaining approximately constant via a parallel connection. This study provides a feasible pathway to developing a multifunctional device with electrothermally tunable bi-reflected and hyper-reflective states based on two conventional cell geometries, which is promising for lasers and color-related display applications.

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“…The pitch is sensitive to chemical composition. In particular, the pitch of a Ch mixture containing chiral molecules with photosensitive groups, such as azobenzene moieties, could be tuned by an exposure to light which causes trans-to-cis isomerization and thus changes molecular interactions responsible for the equilibrium p [17][18][19][20] . Imagine that an active droplet is placed in a Ch confined between two glass plates, one of which is rubbed to produce a unidirectional alignment along an axis x.…”

mentioning

confidence: 99%

Dynamic control of active droplets using light-responsive chiral liquid crystal environment

Jirón,

Rajabi,

Wang

et al. 2024

Commun Phys

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Microscopic active droplets are of interest since they can be used to transport matter from one point to another. In this work, we demonstrate an approach to control the direction of active droplet propulsion by a photoresponsive cholesteric liquid crystal environment. The active droplet represents a water dispersion of bacterial Bacillus subtilis microswimmers. When placed in a cholesteric, a surfactant-stabilized active droplet distorts the local director field, producing a point defect-hedgehog, with fore-aft asymmetry, and allows for the chaotic motion of the bacteria inside the droplet to be rectified into directional motion. When the pitch of the cholesteric confined in a sandwich-like cell is altered by light irradiation, the droplet trajectory realigns along a new direction. The strategy allows for a non-contact dynamic control of active droplets trajectories and demonstrates the advantage of orientationally ordered media in control of active matter over their isotropic counterparts.

show abstract

Photocontrolled capacitive biosensor based on photoresponsive azobenzene-doped liquid crystals for label-free protein assay

Cited by 10 publications

References 29 publications

Dynamic control of active droplets using light-responsive chiral liquid crystal environment

Dynamic control of active droplets using light-responsive chiral liquid crystal environment

Bicolor Tuning and Hyper-Reflective Color Switching Based on Two Stacked Cholesteric Liquid Crystal Cells with Asymmetric Electrothermal Optical Responses

Dynamic control of active droplets using light-responsive chiral liquid crystal environment

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