Sensor node for remote monitoring of waterborne disease-causing bacteria.

Kyukwang Kim,Hyun Myung

doi:10.3390/s150510569

Abstract

A sensor node for sampling water and checking for the presence of harmful bacteria such as E. coli in water sources was developed in this research. A chromogenic enzyme substrate assay method was used to easily detect coliform bacteria by monitoring the color change of the sampled water mixed with a reagent. Live webcam image streaming to the web browser of the end user with a Wi-Fi connected sensor node shows the water color changes in real time. The liquid can be manipulated on the web-based user interface, and also can be observed by webcam feeds. Image streaming and web console servers run on an embedded processor with an expansion board. The UART channel of the expansion board is connected to an external Arduino board and a motor driver to control self-priming water pumps to sample the water, mix the reagent, and remove the water sample after the test is completed. The sensor node can repeat water testing until the test reagent is depleted. The authors anticipate that the use of the sensor node developed in this research can decrease the cost and required labor for testing samples in a factory environment and checking the water quality of local water sources in developing countries.

Highlights

Coliforms are a group of oxidase-negative bacteria that produce acid from lactose or express β-galactosidase, and form yellow colonies of diverse shapes and sizes on membrane filters [1]
(CPI International, Huntington Beach, CA, USA), Colilert® (IDEXX Laboratories, Westbrook, ME, USA), and Coliscan® (Micrology Laboratories, Goshen, IN, USA) are available for testing the presence/absence of coliform bacteria based on this principle, and are widely used and approved by diverse sanitation authorities, including the Republic of Korea Ministry of Environment [6] and the United States Environmental Protection Agency (US EPA) [2]
We propose a low-cost sensor node system that can be placed in the water source or tanks in a factory and automatically and continuously samples water with a self-priming water pump, mixing with media containing a substrate, and checking the color change caused by bacterial growth

Summary

Introduction

Coliforms are a group of oxidase-negative bacteria that produce acid from lactose or express β-galactosidase, and form yellow colonies of diverse shapes and sizes on membrane filters [1]. The chromogenic enzyme substrate test using color indicating chemicals digested by the coliforms is one of the low cost methods used to detect E. coli. (CPI International, Huntington Beach, CA, USA), Colilert® (IDEXX Laboratories, Westbrook, ME, USA), and Coliscan® (Micrology Laboratories, Goshen, IN, USA) are available for testing the presence/absence of coliform bacteria based on this principle, and are widely used and approved by diverse sanitation authorities, including the Republic of Korea Ministry of Environment [6] and the United States Environmental Protection Agency (US EPA) [2] This method relies on bacterial growth in the edia and digestion of a given substrate, and the average time for the test is about 8 to 48 h. In the case of developing countries, individual users of different water sources interested in the presence of E. coli can place the sensor node in the source and check whether the source is contaminated

Bacterial Culture and Chromogenic Enzyme Substrate Assay

Circuit Design and Monitoring System Setup

Assembly of the Sensor Node and System Integration

Conclusions