Grantee Research Project Results
Final Report: Developing a Low-Cost Wireless Device for Real-Time Monitoring of Lead Levels in Drinking Water
EPA Grant Number: SU839450Title: Developing a Low-Cost Wireless Device for Real-Time Monitoring of Lead Levels in Drinking Water
Investigators: Tang, Xiaochao , Song, Xiaomu , Saha, Dipendu , Wang, Po-Yen , Buchter, Gabrielle , Nordfors, Ian , Kienbaum, Madeleine , Wajda, Alexander
Institution: Widener University - Main Campus
EPA Project Officer: Aja, Hayley
Phase: I
Project Period: November 1, 2018 through October 31, 2019 (Extended to October 31, 2020)
Project Amount: $14,935
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2018) RFA Text | Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources , Sustainable and Healthy Communities
Objective:
Exposure to lead via drinking water is a substantial health hazard. The current common practice of measuring lead levels in drinking water is to use analytical chemical analysis that involves sophisticated laboratory instruments. As lead contamination in drinking water is often a close-to-home contamination caused by corroded lead service pipes connecting households to main lines or lead-based pluming within the households, a low-cost and portable device that can be conveniently deployed to individual households to monitor lead levels in drinking water would offer consumers the opportunity to obtain first-hand information about the lead levels in their drinking water. The main objective of this project is to develop a portable low- cost device for detecting lead levels in drinking water. The lead-detecting device consists of two primary components: lead ion-selective electrode (ISE) sensing membrane and a microcontroller- based measuring unit. ISE membrane has proven to show low detection limits, good selectivity, low cost and great potential to be integrated in a miniature device. The ISE membrane in this study utilized polymeric membrane as the matrix with lead-selective ionophores embedded in the matrix. As lead contamination is usually caused by corrosion of lead-based pipes or pluming near or within individual households, the device is designed and developed to potentially detect lead levels in drinking water at consumers’ water taps. The device is designed to detect dissolved lead (Pb II) in drinking water. Lead particles in drinking water are not detected by the device.
Summary/Accomplishments (Outputs/Outcomes):
Hydroxyl type Vinyl Chloride-vinyl Acetate Terpolymer (Van Horn, Mertz & Co. Inc., Conshohocken, PA) was used to create polymeric membrane matrix and allowed for all components to be housed in the membrane. The selected ionophore was Tert-Butylcalix(4)Arene-Tetrakis (Sigma-Aldrich, St. Louis, MO) with its primary function is to differentiate and transport a specific ion (in this case, Pb2+ ions) through a membrane. The solvent selected was Tetrahydrofuram (THF) (Sigma-Aldrichm, St. Louis, MO) which reacts with the resin, and then evaporates when left in an ambient environment. Sodium Tetraphenyl Borate (NaTPB) (Sigma-Aldrich, St. Louis, MO) was utilized as a bonding agent due to its abilities as a cation exchanger. A range of different ionophore : NaTPB : Resin ratios were investigated in order to determine the optimal ratio of the chemicals that yields the desired performance of the membrane. The electrochemical performance of the ISE membranes was tested and analyzed by open-circuit potential (OCP). A limit of detection of 1.0 ´ 10-7 M was achieved along with a linear Nernstian response over a lead concentration range from 1.0 ´ 10-7 M to 1.0 ´ 10-4 M as shown in Figure 1. Durability test of the membrane showed a lifetime close to 30 days.
Figure 1. Results of open-circuit potential tests: (a) EMF responses to varying lead concentrations; (b) linear fit showing Nernstian slope of 29.3 mV decade-1 over lead concentration range 10-7 M to 10-4 M.
As one of the goals of this project is to develop a device that is low-cost and affordable to allow for widespread use, the project team has designed an amplification circuit to measure the low potential between the electrodes. The working electrode and reference electrode are connected to the coaxial input (Figure 2-a). A radio frequency interference (RFI) filter is placed at the input to cut off unwanted interference generated by electronic and electrical devices. The RC Filter at the input to the LT1167 Instrumentation Amplifier (Analog Devices, Wilmington, MA) is an effective way to reduce rectification of High Frequency Out-of-Band signals (Figure 2-a). At the output of the instrumentation amplifier, a Notch Filter AD8542AR (Analog Devices, Wilmington, MA) is used to remove any line noise during a measurement while the instrument is plugged to an AC source for charging. The output from the Notch Filter is fed to the analog input of a commercial off-the-shelf microcontroller Arduino MKR WIFI 1010. A MKR WIFI 1010 module is used due to its 12-bit ADC capability which provides a signal measurement resolution between 0 and 4095. The Arduino MKR WIFI 1010 also has a wireless module that can transmit data to a web portal. Measurements are fed to a LCD display.
A printed circuit board (PCB) was created for the circuit (Figure 2-b and Figure 2-c). The cost of the prototype is estimated to be around $84.01 per unit. The cost is anticipated to be significantly less for large quantity or mass production. OCP testing with the prototype showed its ability to identify the limit of detection of the ISE sensing membrane.
Figure 2. Custom-built low-cost amplification unit: (a) block diagram of circuit; (b) circuit board with a mounted microcontroller that has a wireless module; (c) encased with LCD display.
The development of the ISE membrane electrode and the custom-built low-cost amplification unit in this study paves the way to create low-cost and yet robust devices for real- time monitoring of lead levels in drinking water in individual households. This in turn would enable the widespread use of such affordable devices and the associated dissemination of first- hand data at the consumers’ end. Such real-time pervasive monitoring at the consumers’ end would likely prevent the potential disastrous consequences like those of Flint’s water crisis.
Journal Articles:
No journal articles submitted with this report: View all 1 publications for this projectSupplemental Keywords:
ion-selective electrode (ISE) membrane, open-circuit potential (OCP), limit of detection (LOD)Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.