Michel Mitov
France
CNRSCNRS, Université Côte d'Azur (France)
Presentation title: Cholesteric optical tags with complex twist
The structural characteristics of cholesteric liquid crystals give rise to wavelength- and polarization-selective properties of reflected and transmitted light beams. The tuning of helix pitch, sense of twist, and in-volume orientation of the helical axis allows for the modulation of the pattern, color, and polarization of optical films. This phenomenon has been observed in beetles, fish, and plants with iridescent structural colors [1]. It is relevant to optical signaling in functional facades, camouflage skins, photonic actuators, anti-counterfeiting labels, and cryptography [2, 3]. We contribute to the topic through the physical design of time-temperature loggers that combine twisted and untwisted structures [4] (Fig. 1), bicolor tags resulting from variable surface tensions [5] (Fig. 2), and polychromatic tags generated by different bulky pitch profiles [6] (Fig. 3).
Acknowledgements: Support by the French government through the France 2030 investment plan managed by the National Research Agency (ANR), as part of the Initiative of Excellence Université Côte d’Azur (ANR-15-IDEX-01).
References:
[1] M. Mitov, Soft Matter, 13, 4176 (2017).
[2] P. Wu, J. Wang, Mater. Horiz., 7, 338 (2020).
[3] J. Zhang, Y. Zhang, J. Yiang, X. Wang, Micromachines, 15, 808 (2024).
[4] C. Boyon, V. Soldan, M. Mitov, ACS Appl. Mater. Interfaces, 13, 30118-3016 (2021).
[5] M. Mitov, C. Boyon, V. Soldan, ACS Appl. Nano Mater., 5, 10560-10571 (2022).
[6] S. Dhingra, M. Mitov, submitted (2025).