scholarly journals Liquid crystal contact lenses with graphene electrodes and switchable focus

MRS Advances ◽  
2016 ◽  
Vol 1 (52) ◽  
pp. 3509-3515
Author(s):  
Helen F. Gleeson ◽  
S. Kaur
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Contact Lenses ◽  
Optical Power ◽  
Optical Systems ◽  
Large Area ◽  
Alignment Layer ◽  
Age Related ◽  
Voltage Dependent ◽  
Focal Power

ABSTRACTPresbyopia is a ubiquitous age-related disability of the eye, affecting an estimated 1.04 billion people worldwide, reducing their ability to focus on nearby objects. The various solutions to this inevitable vision deterioration are not compromise-free, with a growing need for approaches beyond conventional spectacles. The research motivation for this work is the unique solution offered by liquid crystal (LC) contact lenses to create compromise-free vision across the whole field of view. The distinctive property of LC lenses is that they are switchable, with the application of a voltage activating the lens. The change in focal power is facilitated via a voltage-dependent change in refractive index of the LC. We have successfully demonstrated several versions of electrically switchable LC contact lenses with variable additional optical power of up to +3.00 D, ideal for the correction of presbyopia.This paper offers a review of the optical and electro-optical performance recently demonstrated for the different modes of operation realized in nematic systems, including planar (homogeneous) and vertically aligned (homeotropic) aligned devices. The change in optical power obtained depends on the choice of geometry and LC material. A material with higher birefringence allows a thinner LC-lens layer to achieve a particular focal power. In the homeotropic geometry, the refractive index of the LC layer is a minimum in the ‘off’ state (ordinary refractive index, no) and the mode is polarization-independent, offering a significant advantage over planar lens designs. The construction is also simplified as only one alignment layer needs to be rubbed. Depending on the geometry used, continuously variable changes in focal power of up to +3.00D have been achieved. The response time of the lenses can be better than half a second, achieved with small applied voltages of ~7Vrms.A further important stage in the optimization of the contact lenses is the inclusion of graphene as the electrodes. Conventional ITO electrodes are too brittle for these flexible optical systems. The paper also reviews the successful incorporation of graphene into the lenses, with excellent optical and electro-optical results. The device demonstrates the huge potential of graphene in an unconventional liquid crystal device geometry that includes curvature over a relatively large area.

scholarly journals Liquid Crystal Microlens Using Nanoparticle-Induced Vertical Alignment

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Shug-June Hwang ◽  
Yi-Ming Shieh ◽  
Kuo-Ren Lin
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Focal Length ◽  
Nonuniform Distribution ◽  
Vertical Alignment ◽  
Alignment Layer ◽  
Focus Effect ◽  
Oligomeric Silsesquioxane ◽  
Poss Nanoparticle

The nanoparticle-induced vertical alignment (NIVA) of the nematic liquid crystals (LC) is applied to achieve an adaptive flat LC microlens with hybrid-aligned nematic (HAN) mode by dropping polyhedral oligomeric silsesquioxane (POSS) nanoparticle solution on a homogeneous alignment layer. The vertical alignment induced by the POSS nanoparticles resulted in the formation of a hybrid-aligned LC layer with concentric nonuniform distribution of the refractive index in the planar LC cell, which subsequently played the role of the lens, even in the absence of any applied voltages. The dimensions of the concentric HAN structure significantly depend on the volume of the microdroplet and the POSS concentration. The focus effect of this flat microlens was observed while electrically controlling its focal length using the applied voltages from −50 mm to −90 mm.

scholarly journals Fabrication of TiO2-Embedded Polyimide Layer with High Transmittance and Improved Reliability for Liquid Crystal Displays

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 376
Author(s):  
Seung-Rak Son ◽  
Jongil An ◽  
Jin-Wook Choi ◽  
Jun Hyup Lee
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Indium Tin Oxide ◽  
Liquid Crystal Displays ◽  
Alignment Layer ◽  
Tio2 Nps ◽  
Alkyl Chains ◽  
Display Technology ◽  
High Resolution Images ◽  
The Difference

Construction of liquid crystal (LC) alignment by introducing polyimide (PI) to indium tin oxide (ITO) electrodes is one of the main methods to realize high-resolution images in liquid crystal displays (LCD). However, the loss of transmittance caused by the difference in refractive index between ITO and PI leads to direct degradation of LCD performance. Thus, we herein fabricated a functional hybrid PI alignment layer that reduces the difference in refractive index and greatly increases the transmittance of the device by introducing inorganic titanium dioxide (TiO2) nanoparticles (NP) to the organic PI. The highly refractive TiO2 NPs were surface-treated with stearic acid comprising long alkyl chains to improve their dispersibility and uniformly dispersed in the PI matrix by simply stirring the mixture. The hybrid PI mixture was spin-coated on the ITO substrate, and the resulting LC cell exhibited excellent electro-optical properties. In addition, the reliability of the LC cells was enhanced by the inclusion of the TiO2 NPs, which was confirmed through the evaluation of voltage holding ratio, residual direct current, and LC cell reliability. Overall, functional hybrid PI can be used in advanced display technology for next-generation LC devices that require high transmittance and reliability.

Enhancement of Contrast Ratio by Using Ferroelectric Nanoparticles in the Alignment Layer of Liquid Crystal Display

2008 ◽  
Vol 47 (6) ◽  
pp. 4751-4754 ◽  
Author(s):  
Sudarshan Kundu ◽  
Mitsuhiro Akimoto ◽  
Itaru Hirayama ◽  
Masaru Inoue ◽  
Shunsuke Kobayashi ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystal Display ◽  
Contrast Ratio ◽  
Alignment Layer

scholarly journals Photocontrollable Resistivity Change in Nanoparticle-Doped Liquid Crystal Alignment Layer: Voltage Holding and Discharging Properties of Fringe-Field Switching Liquid Crystal Modes

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 268
Author(s):  
Jeong-Hoon Ko ◽  
Jun-Chan Choi ◽  
Dong-Jin Lee ◽  
Jae-Won Lee ◽  
Hak-Rin Kim
Keyword(s):  
Liquid Crystal ◽  
Power Saving ◽  
Low Frequency ◽  
Fringe Field ◽  
Resistance Level ◽  
Alignment Layer ◽  
Experimental Scheme ◽  
Tunable Range ◽  
Crystal Alignment ◽  
Operation Frequency

In liquid crystal (LC) displays, deriving an optimum resistance level of an LC alignment polyimide (PI) layer is important because of the trade-off between the voltage holding and surface-discharging properties. In particular, to apply a power-saving low-frequency operation scheme to fringe-field switching (FFS) LC modes with negative dielectric LC (n-LC), delicate material engineering is required to avoid surface-charge-dependent image flickering and sticking problems, which severely degrade with lowering operation frequency. Therefore, this paper proposes a photocontrolled variable-resistivity PI layer in order to systematically investigate the voltage holding and discharging properties of the FFS n-LC modes, according to the PI resistivity (ρ) levels. By doping fullerene into the high-ρ PI as the photoexcited charge-generating nanoparticles, the ρ levels of the PI were continuously controllable with a wide tunable range (0.95 × 1015 Ω∙cm to 5.36 × 1013 Ω∙cm) through Ar laser irradiation under the same LC and LC alignment conditions. The frequency-dependent voltage holding and discharge behaviors were analyzed with photocontrolled ρ variation. Thus, the proposed experimental scheme is a feasible approach in PI engineering for a power-saving low-frequency FFS n-LC mode without the image flickering and image sticking issues.

scholarly journals Alignment Layer of Liquid Crystal Using Plant-Based Isoeugenol-Substituted Polystyrene

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 547
Author(s):  
DaEun Yang ◽  
Kyutae Seo ◽  
Hyo Kang
Keyword(s):  
Liquid Crystal ◽  
Surface Energy ◽  
Polymer Film ◽  
Uv Irradiation ◽  
Molar Content ◽  
Polymer Modification ◽  
Alignment Layer ◽  
Energy Value ◽  
Alignment System ◽  
Molar Percent

We synthesized a series of renewable and plant-based isoeugenol-substituted polystyrenes (PIEU#, # = 100, 80, 60, 40, and 20, where # is the molar percent content of isoeugenol moiety), using polymer modification reactions to study their liquid crystal (LC) alignment behavior. In general, the LC cells fabricated using polymer film with a higher molar content of isoeugenol side groups showed vertical LC alignment behavior. This alignment behavior was well related to the surface energy value of the polymer layer. For example, vertical alignments were observed when the polar surface energy value of the polymer was smaller than approximately 3.59 mJ/m2, generated by the nonpolar isoeugenol moiety with long and bulky carbon groups. Good alignment stability at 100 °C and under ultraviolet (UV) irradiation of 15 J/cm2 was observed for the LC cells fabricated using PIEU100 as a LC alignment layer. Therefore, renewable isoeugenol-based materials can be used to produce an eco-friendly vertical LC alignment system.

scholarly journals Demonstration of a Polymer-Based Single Step Waveguide by 3D Printing Digital Light Processing Technology for Isopropanol Alcohol-Concentration Sensor

2021 ◽  
Author(s):  
Kankan Swargiary ◽  
Romuald Jolivot ◽  
Waleed Soliman Mohammed
Keyword(s):  
Refractive Index ◽  
3D Printing ◽  
Limit Of Detection ◽  
Optical Power ◽  
Alcohol Concentration ◽  
Single Step ◽  
Gap Size ◽  
Digital Light Processing ◽  
Fused Deposition ◽  
The Core

AbstractA polymer based horizontal single step waveguide for the sensing of alcohol is developed and analyzed. The waveguide is fabricated by 3-dimensional (3D) printing digital light processing (DLP) technology using monocure 3D rapid ultraviolet (UV) clear resin with a refractive index of n = 1.50. The fabricated waveguide is a one-piece tower shaped ridge structure. It is designed to achieve the maximum light confinement at the core by reducing the effective refractive index around the cladding region. With the surface roughness generated from the 3D printing DLP technology, various waveguides with different gap sizes are printed. Comparison is done for the different gap waveguides to achieve the minimum feature gap size utilizing the light re-coupling principle and polymer swelling effect. This effect occurs due to the polymer-alcohol interaction that results in the diffusion of alcohol molecules inside the core of the waveguide, thus changing the waveguide from the leaky type (without alcohol) to the guided type (with alcohol). Using this principle, the analysis of alcohol concentration performing as a larger increase in the transmitted light intensity can be measured. In this work, the sensitivity of the system is also compared and analyzed for different waveguide gap sizes with different concentrations of isopropanol alcohol (IPA). A waveguide gap size of 300 µm gives the highest increase in the transmitted optical power of 65% when tested with 10 µL (500 ppm) concentration of IPA. Compared with all other gaps, it also displays faster response time (t = 5 seconds) for the optical power to change right after depositing IPA in the chamber. The measured limit of detection (LOD) achieved for 300 µm is 0.366 µL. In addition, the fabricated waveguide gap of 300 µm successfully demonstrates the sensing limit of IPA concentration below 400 ppm which is considered as an exposure limit by “National Institute for Occupational Safety and Health”. All the mechanical mount and the alignments are done by 3D printing fused deposition method (FDM).

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