Towards an autonomous microfluidic sensor for dissolved carbon dioxide determination

In this work, we present a new system for the determination of dissolved carbon dioxide (from 7.2 ppm to 425.6ppm) in aqueous environments. Microfluidic technology has been incorporated in sensor design to reduce the volume of samples and reagents. Moreover, a detection system has been integrated in the chip, consisting of a white light-emitting diode as a light source and a high-resolution digital colour sensor as the detector, which are able to detect changes in colour produced by the reaction of the sensing chemistry and carbon dioxide in water. The optimised parameters found for the system are: flow rate 0.6 mL·min-1, integration time 30 s and the time for pumping of solutions was 3 min, obtaining a LOD of 7.2 ppm. The CO2 response, reproducibility, precision, and stability of the sensing chemistry have been studied and compared with those obtained using benchtop instrumentation (i.e. a spectrophotometer), obtaining good agreement.Talentia Postdoc Program launched by the Andalusian Knowledge Agency, co-funded by the European Union’s Seventh Framework Program, Marie Skłodowska-Curie actions (COFUND – Grant Agreement nº 267226)European Union's Horizon 2020 research and innovation programme under grant agreement No 706303 (Multisens)Spanish MINECO (CTQ2016-78754-C2-1-R)Unidad de Excelencia de Química aplicada a biomedicina y medioambiente of the University of GranadaScience Foundation Ireland (INSIGHT Centre, Grant Number SFI/12/RC/2289)European Union (FP7 NAPES project, Project ID: 604241