Fiber Optic Sensor for Simultaneous Determination of Atmospheric Nitrogen Dioxide, Ozone, and Relative Humidity

Abstract

We describe a novel optical sensor for the simultaneous measurement of atmospheric nitrogen dioxide (NO(2)), ozone (O(3)), and relative humidity (RH). A transparent backing thin layer silica gel chromatographic plate impregnated with 8-amino-1-naphthol-5-sulfonic acid (ANS) is used as the collection/sensor element. The plate transmittance is probed by three discrete light emitting diodes (LEDs) centered, respectively, at 442, 525, and 850 nm. The transmission of the plate changes reversibly across visible to NIR wavelengths as the RH around the plate changes; this is the basis for a limited-resolution RH sensor. The ANS on the plate reacts to form brown and pink colored products, respectively, when it reacts with NO(2) and O(3). The sample air impinges on the plate via an entrance nozzle. The LEDs are alternately turned on in a preprogrammed manner and the light is brought to the impregnated face of the plate by a three-legged fiber optic. The transmitted light is detected on the obverse side of the plate. The 850 nm signal provides the RH value and optionally serves as the reference measurement for the other two wavelengths; the NO(2) and O(3) reaction products do not absorb at this wavelength. The absorbance at 442 and 525 nm, thus referenced against 850 nm, are used to obtain NO(2) and O(3) concentrations from a pair of simultaneous equations. For a sampling period of 5 min, the limits of detection (LOD) based on 3 times the standard deviation of blank responses were 0.64 and 0.42 ppbv for NO(2) and O(3), respectively. Data obtained with collocated commercial instruments (O(3) induced chemiluminescence analyzer for NO(2) and UV-absorption for O(3)) show good agreement. Overall, this provides a viable affordable approach for inexpensive measurement of atmospheric NO(2) and O(3).

Materials and Transducers Toward Selective Wireless Gas Sensing

“…351,468 Thus, putting the sensor design phases into the broad perspective of TRLs should provide important guidance for more efficient sensor development. Over the years, representative examples of sensors that have matured for practical applications include those based on metal-oxide semiconductors, 469 dielectric polymers, 470 colorimetric films, 471 chemiluminescent films, 472 and conducting polymer composites. 201 …”

Nano-assembled thin film gas sensors. IV. Mass-sensitive monitoring of humidity using quartz crystal microbalance (QCM) electrodes

“…In particular, the humidity sensing in fuzzy control systems in buildings with high occupant densities for the thermal comfort is highly important and will be useful for the energy and cost efficiency management that becomes a worldwide mission regarding the reduction of carbon dioxide emission [3]. In addition, cheap humidity sensors that are able to operate in the range of 30-80% rH can be synchronised to improve the performance of other gas sensors that are strongly influenced by the surrounding humidity in real environments [4,5].…”

A fiber optic sensor with a metal organic framework as a sensing material for trace levels of water in industrial gases

“…These sensors were based on solid phases impregnated with reagents to collect and concentrate the analyte, and show color changes in response to the analyte for detection. Atmospheric NO 2 and O 3 have been detected simultaneously with the reagent 8-aminonaphthylsulfonate, which reacts with NO 2 and O 3 to generate different colors [12]. In this case, light emitting diodes (LEDs) and a photodiode (PD) were used to observe the developed colors, and M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 atmospheric NO 2 and O 3 were detected within 5 min [12].…”

“…Atmospheric NO 2 and O 3 have been detected simultaneously with the reagent 8-aminonaphthylsulfonate, which reacts with NO 2 and O 3 to generate different colors [12]. In this case, light emitting diodes (LEDs) and a photodiode (PD) were used to observe the developed colors, and M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 atmospheric NO 2 and O 3 were detected within 5 min [12]. A fiber optic gas sensor with calix [4]arene derivatives has been used to detect reversibly parts-per-million by volume (ppmv) levels of NO 2 [13], and a sensor with cobinamide has been used to detect cyanide in blood after pervaporation by the colored vitamin B12 [14].…”