Grant: Special Research Opportunity Program - Inter-American Collaboration in Materials Research

The transport of colloidal particles in confined environments occurs in nature as well as in engineered devices. The emerging area of microfabricated lab-on-a-chip systems aims at creating integrated small-scale devices that incorporate several bio-chemical functions such as sample analysis, synthesis and compound delivery. Many lab-on-a-chip devices transport small particles through their microfluidic channels; fluorescent particles are used as markers for biomolecules and drug-laden particles are used as drug carriers for advanced drug delivery. Even particles much smaller than the width of the flow channels have been found to deposit systematically in specific locations. Over time particles build up in these locations and block flow passages, which in most cases leads to device failure. In previous work particle deposition in microchannel contractions has been described in general terms for suspensions of particles of uniform size as well as for suspensions with a range of particle sizes. In contrast, the work proposed here will aim at quantifying this mechanism in order to allow designing microfluidic systems that either prevent deposition from occurring, or that lead to predictable particle deposition inside a microfluidic device. Specifically, we will focus on the effect that channel geometries and flow conditions, as well as materials such as the surfaces of channels and particles as well as the pH and ionic strength of the liquid phase have on particle adhesion and subsequent channel clogging. For this purpose, microfluidic experiments will be coupled with particle flow simulations, both covering a wide range of geometries and materials. This project is a collaboration between Dr. Stoeber at the University of British Columbia in Canada (experimental work) and Dr. Drazer at the Johns Hopkins University in the US (theoretical work).