A research group led by Dr. Jialei He from Nagoya Universitys Graduate School of Engineering has established a technique for processing cholesteric liquid crystals (CLCs) into micrometer-sized round particles. The group integrated round CLC particles with easily available pigments to develop an anti-counterfeiting QR code that is only visible under a particular circular polarizer. As soon as recognized, CLCs that imitate the units that create the colors of the exoskeletons of beetles are synthesized in the lab since of their unusual colors and properties, which lie in between liquids and crystals.
To make use of CLCs more successfully, researchers produce round CLC particles. These codes would integrate the color of round CLC particles with non-chiral, commercially available pigments, and could only be read with a specific circular polarizer that permits non-chiral light but obstructs the chiral light of the QR code.
Optical Properties of Cholesteric Liquid Crystals
The optical homes of CLCs are particularly advantageous. CLCs consist of long particles that duplicate themselves in the shape of a helix. If the helix has duplicating systems that are close together, the liquid crystal has a brief pitch and reflects shorter wavelengths of light, offering off blue and violet colors.
Moreover, due to the helical plan of molecules in the crystal, the perceived color can change based upon the viewers orientation to the helix, offering a practically limitless palette of colors.
One prospective application for this research study is the creation of more protected QR codes that can not be replicated. Credit: Yukikazu Takeoka and Jialei He
Producing Spherical CLC Particles
To exploit CLCs more effectively, scientists produce round CLC particles. To resolve this, scientists Jialei He and Yukikazu Takeoka from Nagoya University, along with their colleagues, used a mixture of solvents to produce micrometer-sized round CLC particles using a method understood as dispersion polymerization.
Discovering this new method was challenging due to the soft nature of the samples at space temperature level. “The sample testing was an especially difficult time due to the softness of the samples at space temperature level, which is a residential or commercial property inherent to CLCs,” said Dr. He. “Consequently, a substantial amount of effort was needed to discover a suitable technique to define the samples without triggering any damage.”
Development of Monodisperse Spheres
Considering that the pitch of the cholesteric liquid crystal in round CLC particles differs with the particles curvature, the group concentrated on producing particles of uniform size, likewise referred to as monodisperse spheres.
” During the experiment, we all of a sudden discovered that the particle size of the microspheres substantially affected the resulting structural color. We might produce a range of colors depending on particle size,” stated Dr. He. “We also discovered that covering the spherical CLC particles with the polymer polydimethylsiloxane enhanced the pigmentation and thermal stability.”
Anti-Counterfeiting Applications and Future Prospects
A crucial possible application for this research study is the production of more secure, unreplicable QR codes. By utilizing the chirality of CLCs– an asymmetrical residential or commercial property that avoids a things or molecule from being superimposed onto its mirror image– researchers could develop anti-counterfeiting QR codes. These codes would combine the color of round CLC particles with non-chiral, commercially offered pigments, and might only read with a particular circular polarizer that permits non-chiral light however obstructs the chiral light of the QR code.
” The development of spherical CLC particles advancement resulting from this research study will offer new possibilities for low-priced structural color functions different from those of conventional color materials,” said Dr. Takeoka. “As well as being utilized as an unique practical pigment for anti-counterfeiting, it can also be used for other applications that take benefit of the circularly polarized structural color with little angle reliance.”
Recommendation: “Particle Size Controlled Chiral Structural Color of Monodisperse Cholesteric Liquid Crystals Particles” by Jialei He, Sizhe Liu, Guohao Gao, Miki Sakai, Mitsuo Hara, Yuto Nakamura, Hideo Kishida, Takahiro Seki and Yukikazu Takeoka, 9 July 2023, Advanced Optical Materials.DOI: 10.1002/ adom.202300296.
Cholesteric liquid crystals (CLCs) display uncommon colors due to their distinct molecular structure and optical residential or commercial properties that result in the selective reflection of light at specific wavelengths. Credit: Yukikazu Takeoka and Jialei He
Scientists have established a technique to produce distinct anti-counterfeiting QR codes using micrometer-sized spherical cholesteric liquid crystals (CLCs), leading the way for more safe, unreplicable QR codes.
Revolutionizing Anti-counterfeiting: QR Codes Based on Cholesteric Liquid Crystals
A research group led by Dr. Jialei He from Nagoya Universitys Graduate School of Engineering has established a method for processing cholesteric liquid crystals (CLCs) into micrometer-sized spherical particles. CLCs, which exhibit a helical structure, possess distinct optical properties, and they can selectively reflect light. The group integrated round CLC particles with easily available pigments to establish an anti-counterfeiting QR code that is just noticeable under a specific circular polarizer. The research studys findings were released on July 9 in the journal Advanced Optical Materials.
Utilizing the Power of Nature in Engineering
Cholesteric liquid crystals work as an example of how we can draw motivation from nature for engineering functions. The iridescent wings of butterflies or the shiny coating on beetle exoskeletons are examples of the extraordinary phenomena CLCs can generate. When identified, CLCs that mimic the systems that create the colors of the exoskeletons of beetles are manufactured in the lab due to the fact that of their unusual colors and homes, which lie between liquids and crystals.
