Optical Sensor for Real-Time Detection of Trichlorofluoromethane

Abstract

Trichlorofluoromethane was once a promising and versatile applicable chlorofluorocarbon. Unaware of its ozone-depleting character, for a long time it was globally applied as propellant and refrigerant and thus led to significant thinning of the ozone layer and contributed to the formation of the so-called ozone hole. Although production and application of this substance were gradually reduced at an early stage, we still face the consequences of its former careless use. Today, trichlorofluoromethane is released during recycling processes of waste cooling devices, traded on the black market, and according to recent findings still illegally manufactured. Here, we present an optical sensor device for real-time in-situ detection and measurement of this environmentally harmful chlorofluorocarbon. The described sensor is based on a planar Bragg grating that is functionalized with cyclodextrin derivatives and operates on the principle of a chemical sensor. In our study, the sensor is sensitized using per-methyl-, per-ethyl-, and per-allyl-substituted α -, β -, and γ -cyclodextrins as affinity materials for airborne trichlorofluoromethane. These functional coatings have been proven to be highly efficient, as an up to 400-times stronger signal deflection could be achieved compared to an identical but uncoated sensor. The presented sensor device shows instantaneous response to trichlorofluoromethane exposure, and features a limit-of-detection of less than 25 ppm, depending on the applied affinity material.

Research Progress on Synthesis and Application of Cyclodextrin Polymers

“…The reaction produced a stable supramolecular molecule, which is a color transparent crystal complex that can be used repeatedly. Girschikofsky and Maiko [ 84 ] used permethyl, perethyl, and allallyl which substituted α-CDs, β-CDs, and γ-CDs as the sensitive sensor materials. Liang et al [ 85 ] used the CD molecule itself to obtain multiple chiral centers, and they synthesized benzylureido-β via the reaction of 6-amino-β-cyclodextrin and reactive benzyl isocyanate.…”

Deep UV Formation of Long-Term Stable Optical Bragg Gratings in Epoxy Waveguides and Their Biomedical Sensing Potentials

“…Directly laser-written PBGs realized in doped fused silica layers were efficiently employed as refractive index sensors for fermentation monitoring, concentration measurements of binary mixtures, and for biomedical substance detection using antibody surface layers [ 12 , 13 , 14 , 15 ]. Additionally, significant chemosensory potential for trace gas detection of harmful organic compounds [ 16 ] and ozone depleting trichlorofluoromethane was demonstrated using silica-based PBG sensors which were surface functionalized with cyclodextrin capture coatings [ 17 , 18 ].…”

An FPGA Platform for Next-Generation Grating Encoders

“…In addition, the FPGAs' internal circuit structure and pins can be reprogrammed, with flexible and rich resource extensions, and it is easy to implement subsequent structural and algorithm optimization. Thus, FPGAs are as suitable as the hardware platform to realize high-precision, high-speed, low-latency, parallelization, and large data displacement measurements [32,33]. Therefore, in this paper we present a method using FPGA to implement existing optical algorithms into the circuit structure.…”