detection of so2 at the ppm level with localized surface plasmon resonance (lspr) sensing

Detection and monitoring of so2 is important because it is a representative toxic gas in the atmospheric environment that is emitted from industrial and natural processes. localized surface plasmon resonance (lspr) sensing is a promising method to develop a robust and low-cost sensor for gaseous species. however, with conventional lspr sensing, inorganic gases including so2 are not detectable at the ppm level. in this study, we developed au-nanopatterned chips coated with porous silica, which enabled detection of so2 gas at ppm levels using the lspr sensing system. the au nanopattern was optimized using a finite-difference time-domain simulation and fabricated on quartz substrates using electron beam lithography. the au-nanopatterned chips were coated with porous silica by the sol-gel method, which enables detection of 20 ppm of so2. the sensitivity of the porous-silica-coated chip was four times higher than that of the uncoated chip. modification of the porous silica layer with 3-aminopropyltrimethoxysilane (aptms) using chemical vapor deposition further enhanced the sensitivity to so2 gas, which was 13 times higher than that of the unmodified porous-silica-coated chip. depth profiles by x-ray photoelectron spectroscopy indicated that aptms was uniformly introduced into the porous silica layer. this study demonstrates that porous silica coatings on au-nanopatterned chips and their additional modification with functional groups are potentially important to develop a low-cost and sensitive sensor for inorganic gases such as so2.