Optically-Paired Microfluidics for E. coli Detection

Contamination of food and water by E. coli is a major global health problem. Although most strains are harmless, some are pathogenic and can cause food poisoning, severe infection, and death. The goal of this project is to design a system to optically detect E. coli in real time, with a focus on developing a device to read paper microfluidic chips, which are a low-cost, biodegradable sensing platform. Antibody-conjugated particles placed on a paper chip bind when exposed to E. coli, resulting in a change in optical signal caused by particle-size-dependent scattering. Current detection methods require smartphone processing and computational software, and are prone to error and false readings caused by inconsistent ambient lighting. The process was made more precise by creating a device that reads red, green and blue values of scattered light in a closed casing produced by 3-D printing. Using an Arduino microcontroller instead of a smartphone and desktop software reduces cost and makes the sensor more feasible for use in developing nations. The device could be adapted to detect other bacteria.