Sihui He

Blue-Phase Liquid Crystals for Reflective Projection Displays

A reflective projection display based on blue phase liquid crystal (BPLC) is proposed. The fast response time of BPLC enables color sequential projection display while suppressing color breakup. Methods for reducing the operation voltage of BPLC are also discussed.

Fast-Response Blue-Phase Liquid Crystal for Color-Sequential Projection Displays

Color sequential projection display using a vertical field switching (VFS) polymer-stabilized blue phase liquid crystal (BPLC) is proposed. The VFS-BPLC exhibits submillisecond response time which is useful for suppressing color breakup. The proposed projector also has a small throw ratio. With phase compensation, the distortion from oblique LC panel could be corrected.

Liquid crystal based sensors for the detection of cholic acid

The concentration level of cholic acid is a biomarker for the early diagnosis of liver and intestinal diseases. We present a biosensor platform based on the anchoring transition of 4-cyano-4′-pentylbiphenyl (5CB) liquid crystals at surfactant-laden 5CB/aqueous interfaces for the detection of cholic acid (CA) in aqueous solution. In the biosensor platform, the competitive adsorption of CA at the surfactant-laden 5CB/aqueous interfaces can trigger a homeotropic-to-planar anchoring transition of the 5CB at the interface, which can be easily observed using a polarizing optical microscope. We find that the detection limit of the 5CB based biosensors for CA depends on the pH and ionic strength of the aqueous phase and the headgroup of the surfactants.

Influence of chain lengths of liquid crystals on cholic acid detection

The concentration level of bile acids is a useful indicator for the diagnosis of liver diseases since individual suffering from liver diseases often has a sharp increase in bile acid concentration. Here we present a sensor platform based on the anchoring transition of nematic liquid crystal (LC), 4’, 4-alkylcyanobiphenyls (nCB, n=5-8), at the surfactant-laden LC/aqueous interfaces for the detection of cholic acid (CA) in aqueous solution. In the sensor platform, the competitive adsorption of CA at the surfactant-laden LC/aqueous interface triggers a homeotropic-to-planar anchoring transition of the LC at the interface. We find the detection limit, which is the minimum concentration of CA required to trigger the LC transition, increases with the increase of the chain length of nCB.