Portable and Autonomous Device for Real-time Colorimetric Detection: Validation for Phosphorous and Nitrite Detection

Abstract

Application of autonomous devices has disrupted routine digital monitoring in all the domains specifically in the fields of environmental monitoring, agriculture and allied sector, health care, and medical diagnostics. These modern autonomous field-deployable devices facilitate reliable testing, data acquisition, and efficient and immediate data transmission. Among various popular detection methods, colorimetric detection method is capable of detecting environmental samples with very low concentration with a high level of precision, are cost-effective, and provide ease-of-use. Hence, in this work, a portable, and autonomous device for real-time detection was designed using commercially available light-emitting diode (LED) and a photodiode, having peak response at a wavelength at which the chromophore exhibits absorption, were used to build the colorimetric detection device. The developed device is a portable, highly sensitive, low-cost, and low-power-consuming colorimetric detection platform integrated with Internet of Things (IoT) and Bluetooth modules for online and offline data transmission, respectively. The device functionality was further enhanced by adding other important attributes such as data storage, retrieval, and real-time monitoring capabilities. For the proof-of-concept, phosphate and nitrite samples were tested colorimetrically. Phosphorous was detected in the linear range of 10–100 μM with the limit of detection (LOD) being 0.074 ppm, while nitrite was detected in a linear range of 5–30 μM with LOD of 0.06 ppm. By suitably modifying the optoelectronic components, the developed colorimetric detection platform can be made potentially amenable to sense a variety of analytes.