Publication Date

Summer 2019

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Advisor

Sang-Joon J. Lee

Keywords

blood coagulation, clot analog, co-flow shear rate, fluorescence microscopy, microchannel hemodynamics, particle image velocimetry

Subject Areas

Mechanical engineering; Biomedical engineering

Abstract

Hemodynamics plays an important role in the formation of blood clots, for which changes in hydrodynamic stresses and transport phenomena can initiate or inhibit the clotting process. The fibrin network is highly influential in the structural mechanics of a clot. This work demonstrated an ability to produce clot analogs at the boundary between co-flow fluid streams, and investigated the dependence of clot shape and density distribution on flow conditions. The time evolution of fibrin clots formed in microchannel flow was investigated using fluorescence imaging. Clots were formed in a polydimethylsiloxane (PDMS) microfluidic device which consisted of a Y-shaped microchannel with two inlets and a single outlet. The clotting region had a cross-section that was 300 µm wide and 12 µm deep. The first inlet introduced fresh frozen plasma (FFP), while the second inlet introduced thrombin. Clot analogs were formed at the interface of these two parallel streams at withdrawal flow rates of 100 nL/min, 200 nL/min, and 400 nL/min. These clots were shown to be insensitive to initial co-flow shear rates, exhibiting similar clot shape and density distribution across the different flow rates. Clots that are formed in such an engineered device provide opportunities to mimic in vivo scenarios in which clot density and composition gradients depend on flow conditions.

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