Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

Esteves, C, Ramou E, Porteira ARP, Barbosa AJM, Roque ACA.  2020.  Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies. Advanced Optical Materials. 1902117:1-29.


Fast, real-time detection of gases and volatile organic compounds (VOCs) is
an emerging research field relevant to most aspects of modern society, from
households to health facilities, industrial units, and military environments.
Sensor features such as high sensitivity, selectivity, fast response, and low
energy consumption are essential. Liquid crystal (LC)-based sensors fulfill
these requirements due to their chemical diversity, inherent self-assembly
potential, and reversible molecular order, resulting in tunable stimuliresponsive soft materials. Sensing platforms utilizing thermotropic uniaxial
systems—nematic and smectic—that exploit not only interfacial phenomena,
but also changes in the LC bulk, are demonstrated. Special focus is given to
the different interaction mechanisms and tuned selectivity toward gas and
VOC analytes. Furthermore, the different experimental methods used to
transduce the presence of chemical analytes into macroscopic signals are discussed and detailed examples are provided. Future perspectives and trends
in the field, in particular the opportunities for LC-based advanced materials in
artificial olfaction, are also discussed.

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