IoT enabled microfluidic colorimetric detection platform for continuous monitoring of nitrite and phosphate in soil

Abstract

With the amalgamation of microfluidics and cyber-physical systems, a paradigm shift can be witnessed in the way the devices are conceptualized and developed for many applications, including soil and water monitoring for agricultural application and overall environmental monitoring. Such technological enhancements are leveraged to facilitate on-site detection and quantification by developing miniaturized devices offering multiplexed detection and data transmission across the globe using internet of things (IoT). Herein, a colorimetry-based miniaturized device was developed by incorporating optoelectronic components and employing a poly(dimethylsiloxane) (PDMS) microfluidic device for precise determination of two of the soil macronutrients i.e. nitrogen and phosphorus. Miniaturization and online data monitoring using the IoT and Bluetooth-based modules, along with Arduino microcontroller, lead to generate data, and its monitoring and storage even in the remote locations. Nitrite and phosphorus were detected in a linear range of 1 µM–30 µM and 10 µM–100 µM with limit of detection (LOD) of 0.33 µM (0.021 ppm) and 0.75 µM (0.095 ppm) respectively which is above the prescribed limits. Furthermore, an android app was developed for continuous monitoring using Bluetooth module for short range data transmission. Overall this work demonstrates the microfluidic colorimetric sensing and IoT enabled data monitoring of soil macro nutrients through a cost-effective platform which opens up avenues for the development of miniaturized point-of-care devices.