CO2-driven Diffusiophoresis of Colloidal Particles and Bacterial Cells

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Surface contamination due to the accumulation of particles and biofilm formation causes fouling of surfaces and malfunction of devices that process particulate materials (e.g. water purifying systems and medical devices).

Researchers at Princeton have invented a novel process and a method for improving existing processes for the separation of particles and water/surface cleaning, including showing a significant effect on bacteria near surfaces. The proposed method describes a new way to manipulate bacterial cells so to delay or reduce their accumulation to a surface. Bacterial cells have a negative surface charge and thus migrate away from a source of CO2, which suggests either formation of an exclusion zone, or slowed down (or no) accumulation of cells at the boundary. Therefore, the method suggests a material or surface design that can introduce CO2 dissolution to reduce particle accumulation or biofilm formation, by removing the cells by diffusiophoresis. Also, the method can focus or concentrate particulate matter including DNA, macromolecules, etc. to achieve charge regulated particle separation. Therefore, by tracking particles, we not only achieve manipulation of charged materials, but also indicators for particle surface charge, pH, and CO2 concentration in the system.


-Delays biofilm formation

-Water cleaning processes

-Achieve anti-(bio)fouling surfaces



-Easy to implement

-Useful in the systems with small length scales

-A cost effective and environmental-friendly method that utilizes CO2 gas

-Combine physicochemical and fluid dynamical effects to achieve directional motion of contaminants

Stage of Development

The inventors have tested the method by using the CO2 sources with moving and fixed boundaries. Bacterial cells with different characteristics were tested for CO2-driven diffusiophoresis, and the inventors demonstrated that the bacteria removal in the vicinity of CO2 source is achieved for both Gram-positive and Gram-negative bacteria, and for both motile and immotile cells. Since most bacterial cells have a negative surface charge, we obtain a general conclusion that the method can improve anti-biofouling properties of surfaces near a CO2 source.



Howard Stone is the Donald R. Dixon ’69 and Elizabeth W. Dixon Professor and Chair for the Department of Mechanical and Aerospace Engineering. Professor Howard A. Stone received the Bachelor of Science degree in Chemical Engineering from the University of California at Davis in 1982 and the PhD in Chemical Engineering from Caltech in 1988. Following a postdoctoral year in the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, in 1989 Howard joined the faculty of the (now) School of Engineering and Applied Sciences at Harvard University, where he eventually became the Vicky Joseph Professor of Engineering and Applied Mathematics. In 1994 he received both the Joseph R. Levenson Memorial Award and the Phi Beta Kappa teaching Prize, which are the only two teaching awards given to faculty in Harvard College. In 2000 he was named a Harvard College Professor for his contributions to undergraduate education. In July 2009 Howard moved to Princeton University.

Professor Stone's research interests are in fluid dynamics, especially as they arise in research and applications at the interface of engineering, chemistry, physics, and biology.  In particular, he and his group developed original research directions in microfluidics including studies and applications involving bubbles and droplets, red blood cells, bacteria, chemical kinetics, etc. He received the NSF Presidential Young Investigator Award, is a Fellow of the American Physical Society (APS), and is past Chair of the Division of Fluid Dynamics of the APS. For ten years he served as an Associate Editor for the Journal of Fluid Mechanics, and is currently on the editorial or advisory boards of New Journal of Physics, Physics of Fluids (until 31 December 2015), Langmuir, (until  31 December 2015), Philosophical Transactions of the Royal Society, Soft Matter, and is co-editor the (new) Soft Matter Book Series.  He is the first recipient of the G.K. Batchelor Prize in Fluid Dynamics, which was awarded in August 2008. He was elected to the National Academy of Engineering in 2009, the American Academy of Arts and Sciences in 2011 and the National Academy of Sciences in 2014.

Suin Shim is a Postdoctoral Research Associate in the Department of Mechanical and Aerospace Engineering. Suin Shim received the Bachelor of Engineering degree in Mechanical Engineering from Pohang University of Science and Technology (POSTECH) and the PhD in the Mechanical and Aerospace Engineering from Princeton University. Currently she is continuing her research as a postdoctoral researcher. Her research interests are in various interfacial flow problems and their applications, which include studies on CO2-driven diffusiophoresis and their applications to water/surface cleaning and particle separation, effect of channel flow on the motion of charged particles, effect of surfactants on the dissolution of CO2 bubble, and controlled evaporative cooling using a thin film flow of water.


Intellectual Property Status

Patent protection is pending.

Princeton University is currently looking for Industry collaborators to further develop and commercialize this technology.



Prabhpreet Gill

Princeton University Office of Technology Licensing • (609) 258-3653•

Patent Information:
For Information, Contact:
Prabhpreet Gill
Licensing Associate
Princeton University
Suin Shim
Howard Stone