低温冷冻下颅脑热-力耦合分析

Thermo⁃Mechanical Analysis of Brain Tissue During Freezing

虽然大脑是人体最重要的器官,但其在低温冷冻过程中的热-力耦合机理仍不明晰.该文考虑颅脑特殊形状、多孔弹性、脑脊液流动、颅骨约束以及冻胀效应,建立脑组织低温冷冻热-力耦合模型,通过分析冷冻过程中的温度场、相场和脑脊液冻胀产生的压力场,发现在凝固过程中脑脊液温度保持不变,而脑组织内部最大温差可达20 K.固-液相界面厚度约0.3 mm,推进速度约0.09 mm/s.冻胀产生的脑组织最大位移(~0.12 mm)发生在靠近头盖骨处.固液界面处压力梯度高达500 MPa/mm,而固体和脑脊液内部压力几乎不变.本研究可为人类大脑的低温冷冻保存策略及脑防护提供理论支撑.

Although the brain is the most important organ in the human body,its thermo-mechanical coupling mechanism during cryogenic freezing remains unclear.A thermo-mechanical model for the cryogenic freezing of brain tissue was established,considering the special shape of the skull and brain,the cerebrospinal fluid,the cranial constraints,and the frost-heave effects.Analyses of the temperature field,the phase field,and the pres-sure field caused by the frost heave of the cerebrospinal fluid during freezing show that,the temperature of the cerebrospinal fluid remains unchanged during coagulation,while the maximum temperature difference within the brain tissue could reach 20 K.The solid-liquid phase interface is about 0.3 mm thick,and the driving veloci-ty is about 0.09 mm/s.The maximum displacement of the brain tissue due to freezing is about 0.12 mm near the skull,and the pressure gradient at the solid-liquid interface is as high as 500 MPa/mm,while the pressure in-side the solid and the CSF keeps almost unchanged.This study provides a theoretical support for the human brain cryopreservation strategy and the brain protection.