Localized Thrombus Rheology: A Study Through the Development of a Magnetic Bead Microrheometry System

Open Access
Nilkant, Prithvi
Area of Honors:
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Keefe B Manning, Thesis Supervisor
  • Keefe B Manning, Honors Advisor
  • Peter J Butler, Faculty Reader
  • Margaret June Slattery, Faculty Reader
  • thrombus
  • blood clot
  • rheology
  • elasticity
Cardiovascular disease (CVD) has manifested into a significant public health epidemic over the last thirty years. Atherosclerosis, the most common cause of CVD death, and implantable devices, designed to treat numerous issues resulting from CVD, impact hemodynamics. Consequently, both scenarios increase the likelihood of triggering the coagulation cascade, leading to thrombus formation, and the potential for thromboembolism. Thromboembolism is the breakage and subsequent circulation of a blood clot through the body due to shear stresses induced by blood flow. It substantially increases the risk of many serious medical conditions such as heart attacks or strokes. Studying the elasticity of thrombi can give researchers insight into growth patterns, locations where it is strongest and weakest, and the mechanisms of thromboembolism, which are all imperative when considering the development of preventative treatments and measures. Because thrombi are very heterogeneous materials, it is important to study the elasticity on a local level. The chief objective of this study is to develop and optimize a microrheometry system to test and measure the mechanical properties of thrombi, specifically elasticity. The force from an external magnet was calculated at various points throughout the working range of the experimental system using viscous glycerol-albumin solution samples with embedded fluorescent paramagnetic beads. The displacement of these beads in response to the magnetic force were imaged and tracked over time; Stoke’s law was then used to calculate the drag force on the beads induced by the bar magnet at each position. It was seen that the force from this bar magnet is on the order of piconewtons, and an equation for this force as a function of distance away from the magnet was empirically derived. Preliminary experiments of thrombi of unknown elasticity have been tested. Initial results using our setup show rough elastic displacement responses; thus, there is confidence that in the future, this developed microrheometry system can be used and further refined to measure local elasticities of thrombi.