We demonstrate the dynamic coloration of polymerized cholesteric liquid crystal (PCLC) networks templated by the “wash-out/refill” method in the presence of organic compounds. The reflection colors were modulated by two key approaches, that is, the injection of mutually soluble organic fluids into a microfluidic channel and the diffusion of volatile organic compounds (VOCs). The reversible tuning of reflected colors with central wavelengths between ∼450nm and ∼600nm was achieved by alternative injection of nematic liquid crystal E7 (n_av = 1.64) and benzyl alcohol (n = 1.54) using syringe pumps. The fascinating iridescence with reflection centers from ∼620nm to ∼410nm was presented from the volatilization and diffusion of alcohol as a model VOC. Additionally, the flow velocity of fluid and the diffusion time were adjusted to explore the underlying mechanism for the dynamic coloration of cholesteric networks. This work is expected to extend the study of PCLCs as a dynamically tunable optofluidic reflector, visually readable sensor, or compact anti-counterfeit label in response to organic compounds.

The method for batch continuous production of polymerized cholesteric liquid crystal (PCLC) microdisks based on centrifugal microfluidics was proposed. The prototype centrifugal microfluidic chip was fabricated by the wet-etching technique with a series of ladder-like concentric ring channels whose depths decrease radially. Two types of dye-doped PCLC microdisks with different doping procedures were generated by this method, the tunable lasing properties were characterized, and corresponding potential applications in a micro-cavity laser and optical barcode were demonstrated. The method is also applicable to a broad range of other polymerized materials.

We demonstrate a soft lithography approach for fabrication of a topographically patterned polyvinyl alcohol (PVA) liquid-crystal (LC) alignment layer. This specific approach employs modified micromolding in capillaries for negative replication of the PVA microstructures on indium tin oxide (ITO) substrates from patterned poly(dimethylsiloxane) molds in a single step, leading to planar alignment on the desired regions. By doping with polyhedral oligomeric silsesquioxane nanoparticles, which can induce vertical alignment on bare ITO surfaces, periodic LC phase gratings based on an alternating vertical-aligned/hybrid-aligned nematic geometry are presented as an application, and a theoretical model was used to simulate and examine the experimental results.