Quantitative volatile organic compound sensing with liquid crystal core fibers

Area of Science:

• Materials Science
• Chemical Sensing
• Polymer Science

Background:

• Liquid crystals (LCs) integrated into polymer fibers offer a unique platform for sensing applications.
• The high surface-to-volume ratio of fibers enhances sensitivity and response times for chemical detection.
• Autonomous sensing capabilities are desirable for various environmental and personal monitoring applications.

Purpose of the Study:

• To demonstrate the capability of polymer fibers with liquid crystals to autonomously sense volatile organic compounds (VOCs).
• To quantitatively measure the concentration of specific VOCs like toluene, cyclohexane, and isopropanol.
• To evaluate the sensor's reversibility, repeatability, response time, and sensitivity.

Main Methods:

• Fabrication of polymer fibers incorporating liquid crystals in the core.
• Utilizing the change in LC birefringence as a measure of VOC concentration.
• Testing sensor performance with representative VOCs (toluene, cyclohexane, isopropanol) at varying concentrations.
• Investigating the effect of operating temperature on sensor sensitivity, particularly near the LC-isotropic transition.

Main Results:

• The fibers demonstrated continuous and quantitative measurement of toluene, cyclohexane, and isopropanol.
• Sensor response was fully reversible and repeatable over multiple detection cycles.
• Achieved response times as low as seconds, indicating rapid detection capabilities.
• High sensitivity was observed when operating near the liquid crystal's isotropic transition temperature.

Conclusions:

• Polymer fibers with LCs are effective autonomous sensors for airborne VOCs.
• The sensor technology exhibits fast response times, high sensitivity, and reversibility.
• Combining different LC mixtures can broaden the operating temperature range for versatile applications.
• These textile-based sensors show potential for integration into apparel and furniture, competing with electronic VOC sensors.