Bacterial biofilm found on a catheter. (www.cdc.gov)

Certain types of bacteria regulate gene expression through quorum-sensing, the detection of extracellular levels of signaling compounds produced by bacteria of the same species.  Once bacteria such as E. coli sense their population is sufficiently large to overwhelm a host’s immune system, they will aggregate and form a pathogenic matrix of bacteria, or biofilm.

While previous research already has provided insight into the mechanisms of bacterial quorum-sensing, it is of interest to evaluate drugs targeting biosynthesis of quorum-sensing molecules, such as AI-2 in E. coli.  The next step in this work is to evaluate the effect of biosynthetic pathway products formed in the microfluidic system on bacterial colonies.  A successful drug targeting quorum-sensing molecule biosynthesis will yield products that inhibit biofilm formation.  A MEMS (micro-electromechanical systems) biosensor designed for integrated biofilm detection is thus required for full evaluation of such drugs. 

 Schematic of microfluidic platform for biofilm monitoring. I am working on developing an integrated,optical-absorbance based sensor to detect and monitor bacterial biofilm growth. Once bacteria are deposited on the sensor surface, they will form a biofilm over a period of days. As the biofilm increases in thickness, it becomes less permissive to light. This feature is measured by illuminating the sensor with an LED array, and measuring the electrical output of an external photodiode.


 Bacteral biofilm formed in a microfluidic device. This microfluidic platform allows for continuous optical monitoring of biofilms, providing instantaneous data as to the biofilm state. The platform not only can be used by researchers as a tool to study biofilms, but it can also be applied toward pharmaceutical development. Other types of sensors may be integrated into the platform, allowing for rapid, continuous, multimodal monitoring of biofilms in response to drugs being tested in the platform.