Fabrication of Google-trackable colorimetric test strips for detecting water leakages

Abstract

South Africa is a water scarce country due to the shortage of rainfall. This scarcity is further exacerbated by the loss of water through leakage from faulty pipes. The consequence is the high amount of revenue lost through leakages and the negative health implication from water unavailability. Given this concern, it becomes highly imperative to address the water wastage through leaks by timely identifying and fixing household leaking pipes. While different method of detecting water leaks have been proposed in the literature, they are, however, expensive and difficult to implement. Hence, it is therefore sensible for South Africa to make use of leading leakage detection technology on pressurised systems, which can rapidly alert operators to leaks and breakages, and detect leaks in old, low-pressure reticulation systems. In the last decade, paper-based microfluidic device had become highly useful for environmental monitoring, health diagnosis, and food safety due to their simplicity, ease of use, and cheap application. This study is focused on the fabrication of a trackable microfluidic device (μPADs) to detect water leaks A quantitative research approach and an experimental design were followed. The µPADs were prepared by printing patterns of wax (100 μm width) on the paper surface and melting the wax into the paper to form hydrophobic barriers and put on a hot plate for the wax to penetrate the paper. Solutions of lower to higher pH were also prepared and were introduced to the chlorophenol red test strips and a range of colours from yellow (lower pH) to purple (higher pH) were obtained. Colour change for chlorophenol paper is irreversible and is based on pH variation and not on the amount of water available in a solution. The optimised pH range was wider than the typical grayscale-based image analysis and was successful for a wide pH range of 2–12 measurements. The QR codes attached to the strips enable tracking to obtain the location from which a leakage was detected and this is done with the use of Google analytics which can tell real-time users from the website and their locations. The digital images obtained with the μPADs were analysed using the CIEL*a*b* colour system. The colour change was also validated using both spectroscopy and optical microscope. The study has exhaustively demonstrated that the combination of digital image analysis and a microfluidic paper-based analytical device (μPADs) are highly effective for both quantitative and qualitative analysis, and thus useful for the detection of household water leaks.