On October 25, a team led by Professor Wie Jeong-jae of Hanyang University Department of Organic and Nano Engineering published a study that simulates natural flower shapes to create a three-dimensional microarray that does not have chiral properties and selectively converts the structure to semi-clock and clock chirality using external magnetism.

Chirality refers to properties that do not overlap each other due to a lack of symmetry when a structure is inverted around a vertical line or a point. The symmetry of the center of the vertical line is called mirror symmetry and the symmetry of the center of the point is called point symmetry, and it is expressed that any structure with only one of the two symmetries has an achirality, which is the opposite of chirality.

Professor Wie's research team's three-dimensional micropillar array was manufactured by naturally simulating flowers such as an achiral Phlox Subulata and Mandevilla that has counter-clockwise chirality. The shape of five or six semicircular micropillars arranged radially at regular intervals is achiral because they have mirror and point symmetry. However, since the magnetic particles are arranged horizontally inside the semicircular micropillars in this achiral array, the top of the pillar is designed to be distorted and the chirality of the array appears only when the magnetic field is applied.

The semicircular micropillars twist in the direction to minimize the magnetic repulsive energy with respect to the applied magnetic field direction. The array of clockwise twisted micropillars has counterclockwise chiralties. However, when the direction of the magnetic field direction changes, the micropillars twist to counterclockwise, which causes the arrays to have clockwise chiralities. At this time, the research team also found out that the number of twisted micropillars must be odd, not even, to break all symmetry and establish chiralties.

Three-dimensional and micro-sized counterclockwise or clockwise chiral arrays can be used to selectively detect left-handed or right-handed polarized light or to develop devices that detect binding pairs of genetic proteins, which are expected for future applications.

The study was conducted with the support of the Korea Research Foundation, Lawrence Livermore National Research Institute, and the U.S. Air Force Research Institute, as well as the school expenses research project at Hanyang University. In addition, a joint study was conducted with Dr. Park Se-jin of the Lawrence Livermore National Research Institute and Dr. Koo Ja-hyun of the U.S. Air Force Research Institute.

The paper (Title: On-Demand Dynamic Chirality Selection in Flower Corolla-like Micropillar Arrays) was published in the renowned U.S. international journal ACS Nano (IF=18.027) by Park Jeong-eun, a major in Research Institute of Industrial Science, Hanyang University and Polymer Environmental Convergence Engineering at Inha University who is taking integrated Ph.D. programs took part as the first author.