Optical Fiber-Top Microcavity CO2 Sensor

A new type of fiber-optic CO2 sensor based on a polymer Fabry-Pérot (FP) cavity fabricated on the end face of a standard single-mode optical fiber has been developed. A photo-crosslinkable poly (ionic liquid) (PIL) with strong CO2 adsorption ability was synthesized and then printed on the top of optical fiber by using an home-built in-situ optical printing technology to form an FP cavity for CO2 sensing. Experimental results show such a miniature fiber-optic sensor has wide detection range and relatively fast response time for CO2 detection.

The result of a cycling test for characterization of the dynamic response of the fiber-optic CO2 microsensor shows that the response time of the CO2 microsensor is around 6.5 minutes, which is much faster than that previously reported PIL CO2 sensor (which is about 30 minutes). The fast response time of the CO2 microsensor is attributed to its small size achieved by optical microfabrication process.