Integrated microfluidic array chip and LED photometer system for sulfur dioxide and methanol concentration detection

• A novel integrated microfluidic chip is proposed for formaldehyde analysis.
• The validity of the proposed device is confirmed with formaldehyde concentrations ranging from 1 to 50 ppm.
• The real-world applicability is then demonstrated by measuring the formaldehyde concentration in commercial Chinese herbs.
• The measurement results deviate by no more than 3.7% from those results obtained using colorimetric method.

An integrated platform comprising a PMMA (Polymethyl-Methacrylate) microfluidic array chip and a LED photometer system is proposed for the concentration detection of sulfur dioxide (SO2) and methanol (CH4O). In the proposed device, the sample and reagent are injected into six open chambers on the microfluidic chip and are mixed via a vortex stirring effect. Following the mixing process, a colorimetric reaction is induced between the sample and the reagent by means of a microhotplate positioned beneath the microfluidic chip array. The microfluidic chip is then transferred to a LED photometer system for detection purposes. The experimental results show that correlation coefficients of R2 = 0.9915 and R2 = 0.9941 are obtained when plotting the photometer output voltage against the SO2 and CH4O concentrations of control samples with known concentrations ranging from 50 to 500 ppm. The real-world applicability of the proposed experimental platform is demonstrated by measuring the SO2 concentration in two commercial Chinese herbs and the CH4O concentration in two commercial wines. It is shown that the concentration measurements obtained using the proposed system deviate by no more than 9% from those obtained using standard macroscale methods. Overall, the results presented in this study show that the proposed integrated microfluidic platform provides a compact and reliable tool for SO2 and CH4O concentration measurement purposes.

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