Development of a Micro-Particle Image Velocimetry Platform to Study Thrombosis In Vitro

Open Access
Author:
Harkins, Tice Ryan
Area of Honors:
Biomedical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Keefe B Manning, Thesis Supervisor
  • William O Hancock, Honors Advisor
Keywords:
  • VAD
  • LVAD
  • PIV
  • Micro-PIV
  • thrombosis
  • PDMS
  • microfluidics
Abstract:
Cardiovascular disease is the number one cause of death in the United States, affecting over 600,000 people annually. Many cardiovascular diseases are thought to be caused by a microcirculatory dysfunction. Micro-scale alterations to the blood flow pathway through an implant (e.g. left ventricular assist device, artificial stents, and valves) are one of the known factors that contribute to clot formation. Understanding these micro-scale factors that cause thrombosis is of paramount importance. Few studies have examined flow patterns around geometric irregularities and their effect on coagulation. The goal of this study was to quantify the flow pathway and set up a platform to visualize thrombus development in two channels constructed from a transparent plastic, PDMS. Each channel had a geometric irregularity, crevice or sudden expansion, which served as a nidus of thrombus formation. To quantitatively measure flow, a micro-particle image velocimetry (μPIV) system was coupled with an inverted epi-fluorescent microscope. Due to the nature of μPIV, whole blood could not be used as the fluid medium. A solution to this problem was the use of reconstituted blood composed of tracer-particle seeded plasma and ghost erythrocyte cells in which the hemoglobin and cellular components were removed to achieve optical transparency. The data demonstrated the technique’s ability to generate stable flows within each PDMS channel. Flow maps obtained support the μPIV system’s ability to quantitatively measure flow within a PDMS channel. A backward facing step was observed to greatly reduce the flow speed immediately after the site of expansion. A small crevice was also shown to produce regions of flow stagnation that could increase platelet residency time and promote the adherence of platelets.