Date of Graduation


Document Type


Degree Name

Bachelor of Science

Degree Level



Biomedical Engineering


Kim, Jin-Woo


Zaharoff, David A.

Second Reader

Wochok, Jeffrey C.


Water is one of the most important compounds on Earth. If a water supply is contaminated with a pathogen, it can have devastating results to an individual or a community. This research is directed at constructing an easily reproducible procedure that could increase the sensitivity of detecting and separating bacteria from the current limits of about 100 cells to 10-20 cells per sample with a ultimate goal of a single cell detection. Here, we report a micro-fluidic system to magnetically capture pathogenic bacteria in water followed by rapid impedance detection using Escherichia coli K-12 as a model bacterium. Paramagnetic beads coated with antibodies to target E. coli captured the bacteria under a magnet. By controlling the flow rate of the washing solution (i.e., PBS buffer), the excess unbound free magnetic particles, which were also captured by the magnet, can be removed, allowing for separation of the target cells. This is because each bacterium has multiple magnetic beads (>2 beads per cell), so it is more strongly bound to the magnet as compared to the free magnetic particles. The concentrated cells targeted by magnetic particles could yield a much higher signal of impedance, significantly increasing the detection sensitivity. The significant improvement in the detection sensitivity is mainly attributed to the substantial signal amplification by the magnetic particles. The results demonstrate the excellent potential of our system as a rapid, highly effective and sensitive, and economical way to capture and detect pathogens in diluted water samples.