skip to main content


Search for: All records

Creators/Authors contains: "Nah, So Hee"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract

    The giant circular photo‐galvanic effect is realized in chiral metals when illuminated by circularly polarized light. However, the structure itself is not switchable nor is the crystal chirality in the adjacent chiral domains. Here spindle‐shaped liquid crystalline elastomer microparticles that can switch from prolate to spherical to oblate reversibly upon heating above the nematic to isotropic transition temperature are synthesized. When arranged in a honeycomb lattice, the continuous shape change of the microparticles leads to lattice reconfiguration, from a right‐handed chiral state to an achiral one, then to a left‐handed chiral state, without breaking the translational symmetry. Accordingly, the sign of rotation of the polarized light passing through the lattices changes as measured by time‐domain terahertz spectroscopy. Further, it can locally alter the chirality in the adjacent domains using near‐infrared light illumination. The reconfigurable chiral microarrays will allow us to explore non‐trivial symmetry‐protected transport modes of topological lattices at the light–matter interface. Specifically, the ability to controllably create chiral states at the boundary of the achiral/chiral domains will lead to rich structures emerging from the interplay of symmetry and topology.

     
    more » « less
  2. Abstract

    Liquid crystal elastomers (LCEs) are promising candidates for creating adaptive textile‐based devices that can actively and reversibly respond to the environment for sensing and communication. Despite recent advances in scalable manufacturing of LCE filaments for textile engineering, the actuation modes of various LCE filaments focus on contractual deformations. In this study, manufacture of polydomain LCE filaments with potential scalability by wet‐spinning is studied, followed by mechanical exploitation to program liquid crystal mesogen alignments, demonstrating both contractual and twisting actuation profiles. By plying these LCE filaments into yarns with different twist concentrations, yarn actuation, and mechanical performance is tuned. Yarns plied at 4 twists per cm can generate up to a seven‐fold increase in elastic modulus while maintaining 90% of actuation strain performance from their native filament. The contractual and twisting LCE filaments are then embroidered with varying stitch types to spatially program complex 2D‐to‐3D transformations in “inactive” fabrics. It is shown that a running stitch can actuate up to 15% in strain and create angular displacements in fabric with twisted mesogen alignments. It is envisioned that the wet‐spun polydomain LCE filaments for diverse plied yarn production together with textile engineering will open new opportunities to design smart textiles and soft robotics.

     
    more » « less