Development of a portable, low-cost electrochemical sensor for rapid detection of bacterial contamination in water samples

Project Abstract

Rapid and reliable detection of bacterial contamination in drinking and environmental water sources is critical for safeguarding public health and informing timely treatment decisions. This project presents the design, fabrication, and validation of a portable, low-cost electrochemical sensor capable of rapid detection of bacterial contamination in water samples with minimal sample preparation. The sensor leverages a screen-printed carbon electrode modified with a biorecognition layer consisting of extracellular polymeric substances and aptamer-based probes that selectively bind target bacterial species. When target bacteria bind to the recognition layer, changes in electrochemical impedance and current response are measured using a compact potentiostat integrated with a smartphone-based data acquisition app, enabling real-time data processing and visualization in field conditions. The device architecture emphasizes affordability, portability, and scalability. A disposable single-use sensor strip houses the recognition layer to prevent cross-contamination, while the reusable electronics module provides low-power operation, wireless data transfer, and user-friendly interfaces. The core sensing mechanism exploits impedimetric and amperometric readouts to detect bacterial binding events, with signal amplification achieved through nanostructured electrode surfaces to enhance sensitivity. To extend applicability across diverse water matrices, the sensor design incorporates surface passivation strategies and matrix-tolerant references to mitigate fouling and interference from organic matter, ions, and particulates commonly encountered in surface and groundwater samples. Methodologically, the project integrates sensor fabrication, surface chemistry optimization, and calibration across multiple bacterial surrogates representative of waterborne pathogens, including Escherichia coli and Salmonella spp. A rigorous validation protocol assesses analytical performance metrics such as limit of detection, linear dynamic range, selectivity against non-target microbes, response time, reproducibility, and stability under varying temperature and humidity. Real-world water samples collected from municipal supplies, wells, rivers, and treated effluents are tested to demonstrate robustness, with parallel benchmarking against conventional culture-based methods and qPCR to establish concordance and potential throughput advantages. Preliminary results indicate a limit of detection in the vicinity of 10 to 100 CFU per milliliter for targeted bacteria in clean water matrices, with notable improvements in response time to under 15 minutes and a projected cost per test under a few dollars due to the disposable sensing strip. The device achieves sufficient sensitivity and specificity to function as an early warning tool, enabling point-of-need decision support for water safety management, rapid triage during outbreak events, and community-level monitoring in resource-limited settings. The research advances include a robust data pipeline for offline and online analytics, strategies for scalable manufacturing, and guidelines for regulatory compliance and user training. Potential future directions encompass multiplexed detection for simultaneous monitoring of multiple pathogens, integration with autonomous sampling platforms, and deployment in remote or disaster-stricken environments where rapid assessment of water quality is critical.

Project Overview

What This Project Is About

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A plain-language overview of the topic and what the project investigates.

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The Problem It Addresses

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What problem or gap this project tackles and why it matters to the field or society.

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Objectives of the Project

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1. Develop a simple, portable sensor design that can detect bacterial contamination in water.
2. Create a low-cost fabrication method using readily available materials.
3. Test the sensor with common water pathogens and compare results to standard lab tests.
4. Assess the sensor’s speed, accuracy, and ease of use for non-expert users.
5. Document limitations and potential for real-world deployment.

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What You Will Do Step by Step

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1. Review basic concepts of bacteria, water quality, and electrochemical sensing in simple terms.
2. Design a basic sensor electrode and select affordable components.
3. Assemble the sensor and calibrate it using known samples.
4. Collect data from water samples with varying bacterial levels.
5. Analyze data to determine detection limits and reliability.
6. Compare results with standard lab methods and discuss discrepancies.
7. Evaluate user-friendliness and outline a deployment plan.

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Expected Outcome

The project should deliver a working, low-cost sensor prototype, a performance report, and guidelines for field use, contributing to rapid on-site water quality checks.