Hetero-core fiber-optic surface plasmon resonance sensor with ionic liquid gel coating for CO2 sensing

Abstract

Fiber-optic CO _2 sensors are free of electromagnetic interference and highly resistant to corrosion but often require expensive measurement systems or sophisticated preparation procedures. To address this challenge, we developed a CO _2 sensor comprising a hetero-core fiber-optic surface plasmon resonance sensor coated with an ionic liquid (IL) gel as a cost-effective CO _2 sensing system. Among the various sensors tested, the sensor using ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF _4 ]) as the IL, prepared at a pull-up speed of 4.5 mm s ^−1 , showed the best CO _2 sensing performance. A hybrid membrane of [EMIM][BF _4 ] and a CO _2 -absorbing polymer (monoethanolamine) demonstrated higher sensitivity for CO _2 concentrations ranging from 0 to 100%. The highlight of the proposed system is its low-cost configuration comprising an 850 nm-wavelength LED and a photodiode as the light source and signal detection device, respectively. Along with facile preparation and low-cost system configuration, the proposed system exhibited significant potential for CO _2 sensing in various fields.

Keywords

• CO2 sensing
• fiber-optic sensors
• hetero-core structure
• ionic liquid
• surface plasmon resonance