Development and optimization of a lab-on-a-chip device for the measurement of trace nitrogen dioxide gas in the atmosphere

Abstract

We propose the use of lab-on-a-chip technology for measuring gaseous chemical pollutants, and describe the development of a microchip for the detection of nitrogen dioxide (NO2) in air. A microchip fabricated from quartz glass has been developed for handling the following three functions, gas absorption, chemical reaction and fluorescence detection. Channels constructed in the microchip were covered with porous glass plates, allowing nitrogen dioxide to penetrate into the triethanolamine (TEA) flowing within the microchannel beneath. The nitrogen dioxide was then mixed with TEA and reacted with a suitable fluorescence reagent in the chemical reaction chamber in the microchip. The reacted solution was then allowed to flow into the fluorescence detection area to be excited by an ultraviolet light-emitting diode (UV-LED), and the fluorescence was detected using a photomultiplier tube (PMT). The reaction time, reagent concentration, pH, flow rate and other measurement conditions were optimised for analysis of nitrogen dioxide in air. Preliminary studies with standardized test solutions revealed quantitative measurements of nitrite ion (NO2-), which corresponded to atmospheric nitrogen dioxide in the range of 10-80 ppbv.

Direct Observation of Dispersion and Mixing Processes in Microfluidic Systems

“…This value showed very good agreement with that evaluated from our latest paper (~110 mm). 22 Therefore, we conclude that such a scientific approach has potential for practical use in investigating the diffusion, dispersion, and mixing processes between solutes and solutions in microchannels. This approach also becomes a very powerful tool to design and develop a new microfluidic system for a chemical pretreatment and analysis using microchips.…”

“…Based on the present results, a total microchannel length, required for the reaction of DAN and NO2 -at a total flow rate of 2 mL min -1 , was calculated for a microchannel having 500 mm width ¥ 100 mm depth, and the obtained value showed very good agreement with that obtained for our previous NO2 gas-measuring mTAS experiment. 22 Fig . 6 Comparison of the t-value dependence of DAbs for mechanically fabricated and wet-chemical-etched microchannels.…”

“…Recently, we developed mTAS for a direct measurement of nitrogen dioxide (NO2) gas in the atmosphere with a flowinjection type microchip. [19][20][21][22] Since NO2 is considered to be one of the chemicals responsible for acid rain, it is important to monitor its concentration in real time. In our mTAS, NO2 gas is absorbed via a nano-porous glass plate into a microchip, where it is converted into NO2 -by reacting with triethanolamine (TEA).…”

A three-dimensional vortex microsystem designed and fabricated for controllable mixing

“…Its applications cover health care [2,3] , biological chemistry [4][5][6] , materials chemistry [7] , as well as environmental monitoring [8][9][10] . According to its wide application, some of the functional units, such as injector, separator, mixer, reactor and detector, should be integrated into the microfluidic chip.…”

Process Characterization of the Reactive-Ion Etching of Borosilicate Glass for Microfluidic Channels

“…Lab-on-a-chip technology can monitor environmental pollutants. Takabayashi This technology made it easier for on-site monitoring [4].…”