Liquid Crystals for Chemical and Biological Sensing: Emerging Transduction Strategies beyond Polarized Optical...

Area of Science:

• Materials Science
• Analytical Chemistry
• Biotechnology

Background:

• Liquid crystal (LC) sensors leverage anisotropic soft materials for signal amplification.
• Classical LC sensing, often using polarized-light optical microscopy (POM), faces limitations in quantification and standardization.
• Interfacial molecular events are amplified into macroscopic optical responses by LC materials.

Purpose of the Study:

• To review emerging transduction strategies for liquid crystal (LC) based sensing.
• To explore advancements moving LC sensing beyond conventional birefringent texture analysis.
• To discuss the potential of LC sensors for quantitative and application-relevant readouts.

Main Methods:

• Discussion of classical nematic and cholesteric LC sensing architectures.
• Examination of emerging transduction strategies including photonic, resonant optical, flow cytometry, and machine learning-assisted analysis.
• Analysis of dye-doped LC systems and dynamically reconfigurable complex LC emulsions.

Main Results:

• Emerging strategies convert LC ordering transitions into measurable spectral, scattering, fluorescence, absorbance, or electrical outputs.
• Integration of molecular recognition, LC reconfiguration, and signal generation enables quantitative transduction.
• New approaches enhance compatibility with portable and automated analytical formats.

Conclusions:

• Advanced LC sensing strategies offer quantitative transduction and broader applicability.
• Future opportunities lie in robust platforms for biosensing, environmental monitoring, and point-of-care diagnostics.
• Challenges remain in reproducibility, selectivity, device integration, and scalability.