Microscale confinement features can affect biofilm formation
Aloke Kumar┼1, David Karig¥, Rajesh Acharya┼, Suresh Neethirajan£, Partha P. Mukherjee€,
Scott Retterer┼ and Mitchel J. Doktycz┼
┼
Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
¥
Research and Exploratory Development Department, Johns Hopkins University Applied Physics
Laboratory, Baltimore, MD, USA
£
€
School of Engineering, University of Guelph, Guelph, ON, Canada N1G 2W1
Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
Supplementary Figure 1: A confocal laser scanning microscopy image of the biofilm. The
confocal side bars clearly show the three-dimensional nature of the biofilm. Scale bar represents
40 μm.
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Corresponding author Email: [email protected], Phone: +1 8655748661, Fax: +1 8655745345 1 Supplementary Figure 2: A higher magnification image shows cell division.
Supplementary Figure 3: Complete view of the chip at two different flow rates (top view) at
approximately 12 hrs. (a) Biofilm formation on PDMS surface at a flow rate of 0.8 µL/hr (b)
biofilm formation at a flow rate of 8 µL/hr.
2 Supplementary Figure 4: Atomic force microscope (AFM) images of the biofilm were taken
after the microfluidic device was disassembled and allowed to dry. AFM images of biofilm
formation at two flow rates. (a) EPS production is higher at higher flow rates (~ 8 µL/hr) as
compared to (b) lower flow rates (~0.8 µL/hr).
PIV settings: To conduct PIV analysis, 200 images were taken at a frame rate of 10 fps. PIVlab
was used to create a mask, so that baffles were not considered in the computation. 32x32 pixel
windows were employed for correlation tracking. Validation was performed on the velocity field
to remove spurious velocity vectors.
Supplementary Video 1: This video depicts the backward flow in the channel. The fluid is
seeded with 500 nm fluorescent polystyrene particles. The higher magnification images clearly
show the vortex structure.
Supplementary Video 2: This video shows the time sequence of biofilm formation in the
microfluidic device at 8 µL/hr. The subsequent frames are images that were taken 25 minutes
apart. The video spans a total time for 20 hrs.
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