Liquid crystal-based sensors for selective and quantitative detection of nitrogen dioxide

Abstract

A highly sensitive nitrogen dioxide (NO2) sensor based on orientational transition of a thin film of liquid crystal (LC) supported on a gold surface is reported. Transport of NO2 molecules through the LC film to the LC-gold interface induces an orientation transition in the LC film. The dynamic behavior of the sensor response exhibits a concentration-dependent response rate that is employed to generate an algorithm for quantitative determination of unknown concentrations. Sensitive, selective and reversible detection with minimal effects of environmental fluctuations suggest that these sensors can be used for quantitative NO2 detection for a number of applications.

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

“…Additionally, several secondary factors play an equally important role to the interplay between VOCs and LCs, such as the roughness of the substrate, the chemical functionalities of the sensing material itself, the LC layer thickness, the transport efficiency of the analyte molecules to the LC/interface, and the adsorption–desorption kinetics at the LC‐interface. [ 46,47 ]…”

“…In this work, we focus on the prevailing interaction mechanisms of LC sensing systems with gas analytes, implementing solely thermotropic systems. We report on the sensing capabilities of platforms that exploit not only interfacial phenomena, [ 45–47 ] but also changes in the bulk, [ 43,44,48 ] yielding various measurable outputs. Furthermore, we detail the strategies in which LCs amplify or directly participate in the molecular recognition of gases and VOCs and we provide details on the probing approaches and transduction (this term refers to the ability of converting variations in physical properties such as brightness or electrical conductivity into a measurable signal) methods employed so far.…”

Chemical gas sensors using chiral nematic liquid crystals and its applications

“…Recent studies have shown that cholesteric liquid crystals (CLCs) have great potential to be used as gas or environmental sensors . The peak wavelength of selective reflection (λ max ) of CLCs changes upon interaction with an adsorbed gas …”

“…Recent studies have shown that cholesteric liquid crystals (CLCs) have great potential to be used as gas or environmental sensors. [3][4][5][6][7][8][9][10][11][12][13][14] The peak wavelength of selective reflection (λ max ) of CLCs changes upon interaction with an adsorbed gas. 15 Despite the many research studies conducted on CLCs, we found none that had investigated the relationship between the CLC chemical structures and the shift in λ max upon exposure to different VOCs.…”

New liquid crystals derived from thiophene connected to the 1,2,4-oxadiazole heterocycle

“…Thus, these materials have become good candidates for technologic application in electro-optic displays, in solar cells [6], as sensors [7], for high-density memory storage [8] and in light-emitting diodes (OLEDs) [9].…”