Fluorescent-Dye-Doped Sol−Gel Sensor for Highly Sensitive Carbon Dioxide Gas Detection below Atmospheric Concentrations

Abstract

Optical fluorescence sol-gel sensors have been developed for the detection of carbon dioxide gas in the 0.03-30% range with a detection limit of 0.008% (or 80 ppm) and a quantitation limit of 0.02% (or 200 ppm) CO(2). Sol-gels were spin-coated on glass slides to create an organically modified silica-doped matrix with the 1-hydroxypyrene-3,6,8-trisulfonate (HPTS) fluorescent indicator. The luminescence intensity of the HPTS indicator (513 nm) is quenched by CO(2), which protonates the anionic form of HPTS. An ion pair technique was used to incorporate the lipophilic dye into the hydrophilic sol-gel matrix. TiO(2) particles (<5 microm diameter) were added to induce Mie scattering and increase the incident light interaction with the sensing film, thus increasing the signal-to-noise ratio. Moisture-proof overcoatings have been used to maintain a constant level of water inside the sensor films. The optical sensors are inexpensive to prepare and can be easily coupled to fiber optics for remote sensing capabilities. A fiber-optic bundle was used for the gas detection and shown to work as part of a multianalyte platform for simultaneous detection of multiple analytes. The studies reported here resulted in the development of sol-gel optical fluorescent sensors for CO(2) gas with sensitivity below that in the atmosphere (ca. 387 ppm). These sensors are a complementary approach to current FT-IR measurements for real-time carbon dioxide detection in environmental applications.

Fluorescent-Dye Doped Thin-Film Sensors for the Detection of Alcohol Vapors

“…The optical sensors have also been designed to function in a multianalyte platform for the simultaneous detection of multiple gas analytes. The studies here follow our earlier work in the development of optical sensors for chemicals in both liquid and gas phases [35]- [39].…”

“…The optimum particle size would be approximately 0.5 times the wavelength of interest which, in this case, would be around 250 -350 nm for the emission wavelength of 550 nm from the dye. This method was adapted from CO 2 sensors that we developed recently [39]. One possible method using TiO 2 particles would be to prepare size-controlled TiO 2 particles so that it would correspond to the optimum particle size needed for the emission wavelength.…”

Nanoscaled Fluorescent Films and Layers for Detection of Environmental Pollutants

“…For instance, Sampathkumaran et al reported the development of a sol-gel fluorescent sensor for detecting CO 2 with a detection limit below the amount of CO 2 in the atmosphere (ca. 387 ppm) (Figure 11b) [43]. In their work, a sol-gel fluorescent sensor was modified into silica-doped matrix with 11 by spin coating on glass slides.…”

Fluorescent Chemosensor for Quantitation of Multiple Atmospheric Gases

“…Another class of gas sensor exploits optical properties. The optical gas sensors are used in fire and explosion prevention, healthcare, indoor air quality control, leak detection, food production and process optimization and control, among the other applications [13]. This particulate technology has progressed rapidly and now-a-days the optical gas sensors are capable to monitor multiple gases, sometimes remotely at a distance of a kilometer or more.…”