title: Tools for water quality monitoring and mapping using paper-based sensors and cell phones.
abstract: 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.
authors.affiliation: Biointerfaces Institute and Department of Chemistry & Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L89, Canada.
authors.forename: Clémence
authors.initials: C
authors.lastname: Sicard
authors.affiliation: Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada.
authors.forename: Chad
authors.initials: C
authors.lastname: Glen
authors.affiliation: Biointerfaces Institute, McMaster University, 1280 Main Street West, Hamilton, ON L8S OA3, Canada.
authors.forename: Brandon
authors.initials: B
authors.lastname: Aubie
authors.affiliation: Biointerfaces Institute, McMaster University, 1280 Main Street West, Hamilton, ON L8S OA3, Canada.
authors.forename: Dan
authors.initials: D
authors.lastname: Wallace
authors.affiliation: Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada.
authors.forename: Sana
authors.initials: S
authors.lastname: Jahanshahi-Anbuhi
authors.affiliation: Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Pennings
authors.affiliation: CH2M HILL, Englewood, CO 80112, United States.
authors.forename: Glen T
authors.initials: GT
authors.lastname: Daigger
authors.affiliation: Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada; Biointerfaces Institute, McMaster University, 1280 Main Street West, Hamilton, ON L8S OA3, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Pelton
authors.affiliation: Biointerfaces Institute and Department of Chemistry & Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L89, Canada; Biointerfaces Institute, McMaster University, 1280 Main Street West, Hamilton, ON L8S OA3, Canada. Electronic address: brennanj@mcmaster.ca.
authors.forename: John D
authors.initials: JD
authors.lastname: Brennan
authors.affiliation: Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada; Biointerfaces Institute, McMaster University, 1280 Main Street West, Hamilton, ON L8S OA3, Canada. Electronic address: filipec@mcmaster.ca.
authors.forename: Carlos D M
authors.initials: CD
authors.lastname: Filipe
mesh_terms: D003124:Colorimetry / Q000295:instrumentation; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D046210:Microfluidic Analytical Techniques; D010755:Organophosphates / Q000032:analysis; D010209:Paper; D010575:Pesticides / Q000032:analysis; D000068997:Smartphone; D014874:Water Pollutants, Chemical / Q000032:analysis*; D060753:Water Quality
chemical_list: D010755:Organophosphates; D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Cell phones; Low cost; Paper-based sensors; Pesticide; Water; Webpage