Bacterial biofilms are ubiquitous on a variety of complex surfaces, and they also play a significant role in human health. They are responsible for more than 65% of hospital associated infections (HAIs). Bacterial biofilms form when planktonic bacteria adhere to a surface, such as a medical implant like a urinary catheter, and encase themselves in an extracellular polysaccharide matrix (ECM). This ECM protects the bacteria from traditional antimicrobials, leading to the recurrence and spread of infections. We here present a flexible, impedance-based microsensor custom fabricated on a polymer substrate for monitoring biofilm formation on a catheter. Our evaluation is twofold; (1) utilize an electrodynamic model of bacterial biofilm to study and evaluate the impedance response due to biofilm growth at the surface of the microsensor, and (2) corroborate the model with custom microfabricated flexible impedance sensors on urinary catheters which are exposed to Escherichia coli biofilm.<br/>Impedance sensors provide a simple and sensitive method for characterizing biofilm growth on the surface, which allows early detection of biofilm formation and thereby increases the chances of preventing long term exposure and infection. We have previously demonstrated such sensors for planar, rigid surfaces; here we are attempting to translate this technology to monitor biofilm on surfaces with complex geometries such as medical implants. The sensor response will be affected by a myriad of parameters; the effect of biofilm thickness and electrode spacing on impedance are examined in this work. We utilize a COMSOL based 3D electrodynamic model to simulate the biofilm formed on the surface of cylindrical shell, similar to a urinary catheter. The sensor sensitivity during initial biofilm formation and percent change in impedance for different biofilm thicknesses are also evaluated experimentally using a flexible impedance sensor on the interior lumen of a cylindrical flow system with similar dimensions and electrode design. Experimentally, the absolute impedance is monitored over time during different phases of the biofilm life cycle; these phases include an electrode conditioning/bacteria-free period, attachment, growth, and removal. The theoretical model is used to optimize and analyze our experimental model. This study, apart from optimizing the design of impedance sensors on catheters, can also be applied to a variety of different vulnerable settings impacted by biofilms.

Experimental and theoretical analysis of biofilm formation and growth on cylindrical surfaces with impedimetric sensors

254th National Meeting (2017)

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