Abstract
A PDMS (Polydimethylsiloxane) microfluidic channel coupled with UV–vis fibre-optic spectrometer and new synthesized colorimetric probe was integrated into an optofluidic based Lab-on-a-chip device for highly sensitive and real-time quantitative measurements of fluoride ions (F¯). An ‘S’ shaped microchannel in a microfluidic device was designed to act as microreactor to facilitate the continuous reaction between synthetized colorimetric probe (sensor) and F¯ ions. Following this reaction, the UV–vis optical probe in the downstream detection zone of the microfluidic device was used to capture their spectrum and present as F¯ concentration in real-time conditions. An initial study of the developed colorimetric probe with multi-colour change with several binding and chromophore groups such as –OH, –NH and –NO2 groups confirmed its high sensitivity and selectivity for F¯ ions with a detection limit of 0.79 ppm. The performance of the developed optofluidic device was evaluated for the selective, sensitive detection of F¯ ions including real samples out-performing conventional methods. The technology has advantages such as low sample consumption, rapid analysis, high sensitivity and portability. Presented new Lab-on-a-chip device provides many competitive advantages for the real-time analysis of F¯ ions needed across broad sectors.
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•First report on an optofluidic based microfluidic device for F¯ ion sensing.•Colorimetric sensor shows limit of detection of 0.79 ppm.•Sensor shows multi-step colour change for different concentration of F¯ ion.•Lab-on-a-chip device can be used for real-time analysis of water samples.•Device has ability to detect F¯ ions below the permissible limit.