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Dalton Miller, Jasper Theel, Adam Croteau, Brett Nelson, Dr. Jim Browning, Dr. Ken Cornell

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The CDC estimates that 128,000 people are hospitalized due to foodborne illness each year in the United States. The presence of bacterial biofilms in food-processing settings is a concern for the spread of disease, and is responsible for a significant number of the outbreaks that result in hospitalizations and food recalls. Although food-processing plants can be sterilized to some degree, the current means of doing so uses harsh chemicals and requires production to be halted for extended periods of time. To that end, we have developed a novel cold atmospheric-pressure plasma (CAPP) device to combat these types of biofilms in a more cost effective manner that requires no harsh chemicals. This biofilm removal can be imaged using fluorescence microscopy and quantified by profilometry, which measures the height of the biofilm before and after CAPP treatment. Here we demonstrate that even short (e.g. 5 minutes) CAPP treatments could etch away biofilms in a time-dose dependent fashion. Our findings provide a proof-of-concept that a CAPP device is a viable potential alternative to classic food processing decontamination methods that rely on harsh chemicals.


CAP plasma device can be used to deliver ionized gas to kill bacterial biofilms on multiple substrates including industrial surfaces and organic models.

Materials and Methods

Plasma Experiments:

  • Diagram, well with media and cells and coverslip2 day biofilms incubation at 37°C in 12 well plates
  • Rinse with PBS
  • Pseudomonas fluorescens used.

CAP Device:

  • CAP device with diagram, photo CAP device diagramPlasma is generated due to the parallel plate capacitive discharge that occurs between the
    low-temperature co-fired ceramic (LTCC) plates.
  • Parameters:
    • Exposure distance: 3 mm
    • Exposure time: 5 min
    • Source voltage: 2.1 kV
    • Source frequency: 20 kHz
    • Type: Wide 1”
    • Argon flow: 9 slm


  • Profilometer, photoBruker DekTak XT Stylus Profilometer Parameters:
    • 12.5 μm stylus
    • Resolution: 0.25
    • Can only use non-pathogenic bacteria

Results: Profilometry

Preliminary Conclusion: CAP treatment can remove bacterial biofilms from industrial substrate, and this removal can be measured via profilometry.

Scan of section with biofilm removed
Scan of the section where biofilm was removed. Ignoring some small amounts of particulate left behind, there is a clear distinction between areas with biofilm growth (13500000-2180196) and where the biofilm has been removed by the CAPP device (100000-1000000).
photo of section where biofilm was removed
This is the picture of what the above scan shows. An area where the biofilm has been etched away can clearly be seen, even with just the naked eye.
scan showing edge of biofilm
This shows the edge of where the biofilm grew, with the area just after 360000 being the start of the biofilm and the area before it being the substrate on which nothing had grown.
photo of edge where biofilm grew
This is the picture of what the above scan shows. There is a clear edge where the substrate without biofilm can be seen, and an area where thick biofilm can be seen.

Future Work

scan of etching

Although etching was seen to be possible, it wasn’t consistent. Despite consistently using the same settings on the CAPP device, etching was not consistently seen. This is most likely due to an overlooked factor, but more testing is needed to determine what that factor is.

Optical Profilometry:

Optical profilometry

Optical profilometry could also be used in the same way, but would have some potential advantages, including:

  • can be used with pathogenic bacteria, as it never makes contact with the surface
  • Can produce 3-dimensional surface scans, as seen to the left in a sample scan of an industrial part


SG received support from the Ralph Jones Premedical Fellowship. This project was supported by Institutional Development Awards (IDeA) from the NIH NIGMS under Grants #P20GM103408 and #P20GM109095, the BSU Biomolecular Research Center, and the Vertically Integrated Projects program in the BSU College of Innovation and Design with funding from the Leona M. & Harry B. Helmsley Charitable Trust. Lastly, the project has received funding from the U.S. Dept. of Agriculture under Grant 2018-67018-27881.

Additional Information

For questions or comments about this research, contact Dalton Miller at