Towards an autonomous microfluidic sensor for dissolved carbon dioxide determination

Abstract

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.

Dissolved Carbon Dioxide Sensing Platform for Freshwater and Saline Water Applications: Characterization and Validation in Aquaculture Environments

“…In addition, in what concerns shelf life, the sensing film can be stored in a sodium carbonate solution [36] at low temperatures (2 < T < 10 • C) for at least 6 months, and can be used after a new calibration. As stirring is not needed, the sensor is suitable to be used for continuous dissolved CO 2 monitoring, contrary to the systems used by other authors [14,37].…”