Liquid crystal microcapillary-based sensors for affordable analytical applications.

Area of Science:

• Materials Science
• Chemical Sensing
• Liquid Crystals

Background:

• Liquid crystals (LCs) exhibit stimuli-responsive and optical properties suitable for sensitive detection.
• Amphiphilic species in aqueous media require effective tracking for biological and chemical monitoring.

Purpose of the Study:

• To develop and demonstrate a microcapillary-based method for online detection of amphiphilic species.
• To utilize liquid crystals' responsive properties for sensing applications in aqueous environments.
• To enable continuous tracking of chemical and biological species.

Main Methods:

• Utilized compartments of nematic 4-cyano-4'-pentylbiphenyl (5CB) within cylindrical glass microcapillaries.
• Promoted homeotropic anchoring of LCs, with flat surfaces in contact with aqueous media.
• Characterized equilibrium and nonequilibrium responses of LCs to changes in aqueous interface anchoring.

Main Results:

• Observed the formation and movement of a positively charged defect upon anchoring transition, leading to a four-petal configuration.
• Quantified the transition time to an average of 41 ± 19 minutes, attributed to elastic force imbalance.
• Demonstrated reversible sensor behavior facilitating temporal and cumulative quantification, with metastable states removable via thermal treatment.

Conclusions:

• The microcapillary LC sensor offers a sensitive and rapid method for detecting amphiphilic species.
• The sensor's reversibility and quantification capabilities support continuous monitoring of chemical and biological targets.
• This technology has potential applications in health and safety monitoring requiring real-time tracking.