Ultraviolet control of bacterial biofilms in microfluidic chips

Area of Science:

• Microfluidics
• Bacterial biofilms
• Biophysics

Background:

• Polydimethylsiloxane (PDMS) microfluidic systems are valuable for studying bacterial biofilms and hydrodynamic effects.
• Controlling bacterial cell distribution and boundary conditions in microfluidic flow systems remains challenging.
• Unwanted bacterial colonization limits experiment duration, hindering long-term biofilm biophysics studies.

Purpose of the Study:

• To develop a method for precise control of bacterial growth zones in PDMS microfluidic devices.
• To overcome limitations in current microfluidic biofilm research, enabling extended experimental durations.
• To facilitate the study of biofilm evolution over longer time scales.

Main Methods:

• Integration of ultraviolet-C (UV-C) light-emitting diodes (LEDs) into a 3D printed light guide.
• Irradiation of germicidal UV-C directly through PDMS microfluidic chips to confine bacterial growth.
• Application of the system to control *Pseudomonas aeruginosa* biofilm in mixing zones and define bacterial distribution.

Main Results:

• Successful control of undesired *Pseudomonas aeruginosa* biofilm growth in microfluidic mixing zones for 48 hours.
• Demonstration of controlled bacterial colonization for up to seven days, enabling long-term biofilm studies.
• Validation of the system's ability to define initial bacterial distribution and perturb existing biofilms.

Conclusions:

• The UV-C LED system effectively confines bacterial development to desired areas within PDMS microfluidics.
• This approach significantly extends the feasibility of long-term biofilm experiments in microfluidic devices.
• The low-cost and generalizable nature of this method positions it as a potential standard for PDMS microfluidic biofilm research.