Blood clots are naturally derived bioadhesives that adhere to tissues, plug vascular damage and stop bleeding. Their function of hemostasis hinges on their resistance against rupture (toughness). Despite the relevance, fracture mechanics of blood clots remains largely unexplored, particularly the toughness and critical length scales governing clot fracture have not been reported. Here, we study the fracture behavior of human whole blood clots and platelet-poor plasma clots. The fracture energy of whole blood clots and platelet-poor plasma clots determined using modified lap-shear method is 5.90 ± 1.18 J/m² and 0.96 ± 0.90 J/m², respectively. We find that the measured toughness is independent of the specimen geometry and loading conditions. These results reveal an important contribution of blood cells to the clot fracture, as well as the dissipative length scale and nonlinear elastic length scale governing clot fracture. This study will motivate the investigation on blood clot fracture and inspire the development of clot-mimicking bioadhesives.

血凝块是天然衍生的生物粘合剂，可粘附在组织上，堵塞血管损伤并止血。它们的止血功能取决于它们对破裂的抵抗力（韧性）。尽管具有相关性，但血凝块的断裂力学在很大程度上仍未得到探索，特别是尚未报道控制血凝块断裂的韧性和临界长度尺度。在这里，我们研究了人类全血凝块和贫血小板血浆凝块的断裂行为。使用改良的搭接剪切法测定的全血凝块和贫血小板血浆凝块的断裂能分别为 5.90 ± 1.18 J/m ²和 0.96 ± 0.90 J/m ²， 分别。我们发现测得的韧性与试样几何形状和加载条件无关。这些结果揭示了血细胞对凝块断裂的重要贡献，以及控制凝块断裂的耗散长度尺度和非线性弹性长度尺度。这项研究将推动对血凝块断裂的研究，并激发血凝块模拟生物粘合剂的发展。