Research Projects

Blood clots formed inside the blood vessels or heart (thrombosis) obstructs the passage of blood flow. These clots are highly prone to fragmentation, leading to various pathological disorders for example, Acute Ischemic Stroke. Mechanical thrombectomy is a minimally invasive process that uses a stent retriever or aspiration catheter to retrieve blood clots (thrombus) from arteries or veins. In the current scenario, multiple procedures are required to retrieve the blood clots whilst only two-third of the patients achieve complete revascularisation. Although researchers have tried to improve the design of thrombectomy devices, yet, distal embolism (clots fragment during thrombectomy) still remains a challenge. Hence it is essential to reveal the fragmentation process of such clots. Limited work focused on understanding the time-dependent properties of blood clots of varying compositions while a recent study showed the microstructural changes for fibrin clots (no red blood cells). Although, the mechanical response are highly dependent on clot compositions (red blood cells/fibrin ratio), yet only one study accounted this in Type I loading. Fracture of blood clots during thrombectomy is a rather complicated process involving both dissipative process and intrinsic fracture toughness along various modes of fracture. As such, these factors should be taken into consideration. Overall, a gap exist in understanding the complex fracture mechanics of different types of blood clots. The aim of the project is to understand the complex time-dependent properties and fracture toughness on blood clots having varying clot composition during mechanical loading via complex mechanical behaviour such as viscoelasticity, fracture toughness in various loading modes and time-dependent fracture behaviour along with their microstructural changes. The researchers will start with fabrication of controlled blood clots with varying red blood cells/fibrin ratio using blood from sheep/goat. This will be followed by perform time-dependent experiments such as cyclic loading to understand hysteresis, damage (Mullin’s effect), plastic strain etc. Creep and stress-relaxation will also be employed and viscoelastic parameters will be extracted using viscoelastic models. This will be followed by testing the varying blood clots in different modes of fracture along with their microstructural changes. This structure-function relationship would explain the process of fragmentation of blood clots when mechanical forces are applied. More importantly, the crack growth under various strain-rates and modes of fracture will also be investigated. This research is crucial for future funding opportunities and collaborations as the researchers would try to develop advanced retrieval devices by optimising designs of the device and building computational models (pre-clinical testbeds from the data generated in this study) to test them.