Biointerfaces Institute and Department of Chemistry & Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L89, Canada.
Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada.
Water Res. 2015 Mar 1;70:360-9. doi: 10.1016/j.watres.2014.12.005. Epub 2014 Dec 12.
In this paper we describe a combination of paper-based sensors and a novel smart-phone application for on-site quantification of colorimetric readouts as an ultra-low cost solution to monitoring water quality. The system utilizes a paper-based analytical device (μPAD) that produces a colorimetric signal that is dependent on the concentration of a specific target; a cell phone equipped with a camera for capturing images of two μPADs - one tested with a water sample and the other tested with clean water that is used as a control; and an on-site image processing app that uses a novel algorithm for quantifying color intensity and relating this to contaminant concentration. The cell phone app utilizes a pixel counting algorithm that performs with less bias and user subjectivity than the typically used lab-based software, ImageJ. The use of a test and control strip reduces bias from variations in ambient lighting, making it possible to acquire and process images on-site. The cell phone is also able to GPS tag the location of the test, and transmit results to a newly developed website, WaterMap.ca, that displays the quantitative results from the water samples on a map. We demonstrate our approach using a previously developed μPAD that detects the presence of organophosphate pesticides based on the inhibition of immobilized acetylcholinesterase by these contaminants. The objective of this paper is to highlight the importance and potential of developing and integrated monitoring system consisting of μPADs, cell-phones and a centralized web portal for low-cost monitoring environmental contaminants at a large-scale.
在本文中，我们描述了一种基于纸张的传感器与新型智能手机应用程序的结合，用于现场量化比色读出结果，这是一种超低成本的水质监测解决方案。该系统利用基于纸张的分析设备（μPAD）产生一种比色信号，该信号取决于特定目标的浓度；一部配备摄像头的智能手机，用于拍摄两个μPAD 的图像——一个用水样测试，另一个用清洁水测试作为对照；以及一个现场图像处理应用程序，该应用程序使用一种新颖的算法来量化颜色强度，并将其与污染物浓度相关联。手机应用程序使用一种像素计数算法，与通常使用的基于实验室的软件 ImageJ 相比，该算法具有更小的偏差和用户主观性。使用测试和对照条带可以减少环境光照变化带来的偏差，从而可以在现场获取和处理图像。手机还能够对测试位置进行 GPS 标记，并将结果传输到一个新开发的网站 WaterMap.ca，该网站将水样的定量结果显示在地图上。我们使用先前开发的μPAD 演示了我们的方法，该μPAD 基于这些污染物对固定化乙酰胆碱酯酶的抑制作用来检测有机磷农药的存在。本文的目的是强调开发和集成监测系统的重要性和潜力，该系统由 μPAD、智能手机和一个集中式门户网站组成，用于大规模低成本监测环境污染物。
