Quantitative volatile organic compound sensing with liquid crystal core fibers

Katrin Schelski,Catherine G Reyes,Lukas Pschyklenk,Peter-Michael Kaul,Jan P.F Lagerwall

doi:10.1016/j.xcrp.2021.100661

Abstract

SummaryPolymer fibers with liquid crystals (LCs) in the core have potential as autonomous sensors of airborne volatile organic compounds (VOCs), with a high surface-to-volume ratio enabling fast and sensitive response and an attractive non-woven textile form factor. We demonstrate their ability to continuously and quantitatively measure the concentration of toluene, cyclohexane, and isopropanol as representative VOCs, via the impact of each VOC on the LC birefringence. The response is fully reversible and repeatable over several cycles, the response time can be as low as seconds, and high sensitivity is achieved when the operating temperature is near the LC-isotropic transition temperature. We propose that a broad operating temperature range can be realized by combining fibers with different LC mixtures, yielding autonomous VOC sensors suitable for integration in apparel or in furniture that can compete with existing consumer-grade electronic VOC sensors in terms of sensitivity and response speed.

Highlights

The air that we breathe is a complex mixture of many chemicals, with the fraction composed by volatile organic compounds (VOCs) being of particular interest
Polymer fibers with liquid crystals (LCs) in the core have potential as autonomous sensors of airborne volatile organic compounds (VOCs), with a high surface-to-volume ratio enabling fast and sensitive response and an attractive non-woven textile form factor
We demonstrate their ability to continuously and quantitatively measure the concentration of toluene, cyclohexane, and isopropanol as representative VOCs, via the impact of each VOC on the LC birefringence

Summary

Introduction

The air that we breathe is a complex mixture of many chemicals, with the fraction composed by volatile organic compounds (VOCs) being of particular interest. The presence of certain VOCs in exhaled air can be a sign of severe health conditions,[1] and there is a strong interest in quantitative monitoring of VOCs in air for medical diagnostics.[2] Airborne VOCs can indicate imminent danger, being released by bacterial growth in food[3,4] or by explosive devices;[5] their detection can alert people of spoiled meals or of attempted terrorist attacks. They can have serious health effects upon inhalation, causing disease and/or allergenic reactions. They rarely distinguish between different VOCs, as this is highly challenging for consumer-grade electronics-based sensors.[6,7,8] Better selectivity may be provided from specific chemical interactions between a target

Results

Discussion

Conclusion