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Faculty Advisors

Ryan, Shawn D.; Wirth, Christopher L.


Self-propelled or “active” micrometer scale particles are capable of supplying local mechanical work, necessary for microscale cargo delivery and useful in other applications within bioimaging and sensing. Research in the last decade has focused on developing, measuring, and manipulating the locomotion mechanisms of active particles in simple environments. However, many applications will be in complex environments with nearby boundaries or variations in physiochemical cues. This poster reports the directed motion of platinum coated polystyrene particles at infinite dilution in the presence of H2O2, which acts as a fuel to drive motion. A transport mechanism called “diffusiophoresis” drives motion of the particle as a consequence of the local gradient in chemical species following the breakdown of hydrogen peroxide into oxygen and water on the platinum cap. The apparent swimming speed of the particle increased from 0 m/s to approximately 2 m/s with fuel concentrations between 0% and 10% near a boundary. Complementary simulation work showed clustering as a consequence of the balance between swimming speed and random Brownian diffusion. Finally, the poster will summarize efforts to tune swimming speed by adjusting the physiochemical environment of the particle via the addition of salt and non-adsorbing nanoparticles. Results from this work demonstrate how the local environment will alter the dynamic behavior of active Janus particles.

Publication Date



Washkewicz College of Engineering; College of Sciences and Helath Professions


Chemical & Biomedical; Mathematics


Biomedical Engineering and Bioengineering | Chemical Engineering | Engineering | Mathematics

Boundary effects on the locomotion of active Janus particles