Electrochemical test chip for rapid microbial contamination detection

Overview

This solution is a disposable, paper-based electrochemical test chip designed to detect microbial contamination quickly and affordably. It combines a porous carbon bioanode with an electrochromic cathode (Prussian Blue) in a biofuel cell configuration. When a sample containing microbes is introduced, microbial metabolism of glucose in the electrolyte generates electrons that flow to the cathode, reducing Prussian Blue to transparent Prussian White. The resulting visible color change signals the presence of contamination, offering a simple, rapid alternative to conventional laboratory culture methods that can take days.

The technology builds on prior work developing a handheld biosensor for C. difficile detection and aims to further reduce cost by replacing traditional PDMS microfluidic platforms with paper-based substrates. Potential applications include clinical point-of-care diagnostics, food safety testing, water quality monitoring, and environmental contamination screening.

Technical specifications

• Bioanode: Porous carbon material that supports microbial culture and enables oxidation of glucose to CO₂ and water, releasing electrons.
• Cathode: Electrochromic Prussian Blue that transitions from blue to transparent (Prussian White) upon reduction, providing a direct visual readout.
• Electrolyte system: Dried electrolyte layer on the chip that rehydrates upon sample application, simplifying field use.
• Detection modalities (planned development stages):
  • Disposable test strip format with visual color-change readout (analogous to a pregnancy test)
  • Microbe meter using a galvanometer to quantify current intensity and estimate microbial load
  • Enhanced microbe meter employing cyclic voltammetry to differentiate microbial species, with smartphone connectivity for data display

Technology readiness level

The concept is at an early stage of development. The underlying biofuel cell principle and electrochromic signaling mechanism have been established through prior biosensor work for C. difficile detection on PDMS-based microfluidic platforms. Current efforts focus on translating this approach to a paper-based, disposable format. Validation steps include demonstrating dried-electrolyte rehydration upon sample introduction and confirming the color-change response. Subsequent stages will involve quantifying current intensity for microbial load estimation and developing species-level differentiation via cyclic voltammetry.