In-plane switching of cholesteric liquid crystals for visible and near-infrared applications

We have investigated the in-plane switching of cholesteric liquid crystals for reflective wavelength shifters for visible and near-infrared applications. These devices are based on the elongation of the cholesteric pitch by an electric field perpendicular to the helical axis. The transmission notch-reflection peak position can be tuned continuously to a longer wavelength (redshift) by application of an in-plane electric field. The helix is completely unwound when the electric field is higher than the cholesteric-to-nematic transition field, and the sample is transformed to a transparent state. We have investigated the electro-optic performance of in-plane switching of cholesteric samples and developed a simple phenomenological model to describe the underlying electro-optic phenomena.     

Color gamut of cholesteric liquid-crystal films and flakes by standard colorimetry

Despite angle dependence and polarization selectivity, the color of cholesteric liquid-crystal (CLC) polysiloxane films can be quantified by standard colorimetry. A new fractured form of the film called “flakes” makes it possible to use the Center of Gravity Color Mixing Principle to predict the chromaticity of CLC color mixtures. A complete color gamut can be produced by layering CLC films, mixing CLCs physico-chemically, and mixing CLC flakes. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 210–220, 1998     

Electric-field-induced motion of polymer cholesteric liquid-crystal flakes in a moderately conductive fluid

Polymer cholesteric liquid-crystal flakes suspended in a fluid with nonnegligible conductivity can exhibit motion in the presence of an ac electric field. The plateletlike particles with a Grandjean texture initially lie parallel to the cell substrates and exhibit a strong selective reflection that is diminished or extinguished as the flakes move. Flake motion was seen within a specific frequency bandwidth in an electric field as low as 5 mV(rms)/microm. Flakes reoriented about their longest axis to align parallel to theapplied field, and a rise time of 560 ms was seen in a 40-mV(rms)/microm field at 100 Hz.     

A survey on wireless sensor network databases

Wireless Networks - In recent years, the use of wireless sensors has increased drastically in most fields. Wireless Sensor Networks (WSNs) have attracted the interest of industries and they have...