Bioelectronic Biofilm on Chip—Understanding Biofilm Formation Dynamics Through Combined Optical and Electronic Methods

Biofilm formation, characterized by the aggregation and irreversible adhesive of diverse microorganisms on both biotic and abiotic surfaces, represents a complex process. Biofilms are held together by a self-produced matrix known as extracellular polymeric substances (EPS), which are the main responsible for the high antibiotic resistant feature of the biofilm. Bacterial infections associated with biofilms are accountable for a significant portion of healthcare-associated infections, emphasizing the need for in-depth research into biofilm development and resistance mechanisms. Current in vitro biofilm model systems lack the ability for continuous online monitoring, as they require the removal of the biofilm from the growth substrate, disrupting its natural behaviour. We have developped a microfluidic platform with integrated electrodesfor real-time, and non-disruptive biofilm formation studies. Moreover, it serves as a reliable tool by mimicking the natural behaviour of the biofilm formation under flow conditions, thereby enhancing understanding of biofilm behaviour and enabling the development of more effective prevention and treatment strategies. The microfluidic chip incorporates a gold electrode array coated with Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/PEDOT:PSS which has shown to enhance measurement sensitivity due to its low impedance values. Using our combined optical/ electrochemical platform we acquire insights into the biofilm lifecycle—from initial attachment to dispersion. Additionally, we have tested different antibiotic treatments, revealing varying degrees of resistance and responses to specific treatments. By combining and correlating the electrochemical (electrochemical impedance spectroscopy, EIS) and optical (fluoresence microscopy) data we not only acquire mechanistic understanding into biofilm formation and disruption dynamics but we also reveal figures of merit in EIS for characterizing biofilm health in a quantitative manner. This study lays foundation for applications of electrochemical sensing of biofilms in clinical settings, i.e., for detecting the presence of biofilm- related infections as well as evaluating new antibiofilm strategies.