生物组织生长的修正乘法分解预测模型及力电耦合调控机制研究

Electromechanical effects and tenability using applied electric field of biological tissues have been demonstrated in numerous experimental tests. The developed volumetric growth theory based on multiplicative decompositions only accounts for the elastic growth procedure, which needs a virtual stress-free state as the reference configuration that is difficult to achieve in practice. This project aims to put forward the traditional multiplicative decomposition method by replacing the virtual stress-free state with the real growth state with residual stresses as the reference configurations, as well as accounting for the electromechanical coupling effects of biological tissues. The main missions of this project are to develop free energy functions and constitutive equations for biological growth that including both the effects of residual stresses and electrical field, and to establish the coupling equations that govern the evolution of biological tissues due to mechanical, electrical, biochemical driving effects. The electromechanical finite deformation theory and incremental theory will be employed to tuning analyses of growth and morphological evolution of biological tissues. The outcomes of this project may facilitate to put forward the growth theories of continuum mechanics, and may also provide references for tuning and control of biological growth that is omnipresent in aging, solid tumour growth, tissue engineering, thus to demonstrate the significance of mechanics in biomedical engineering and healthcare applications.

生物组织的力电耦合特性以及受外电场的可调控性已得到大量实验证实，现有生长模型仅局限于弹性生长框架，且需设定虚拟零应力状态为初始构型，应用受到极大限制。本项目提出以具有生长残余应力的真实状态为初始构型，对传统乘法分解弹性生长模型进行修正，构造包含残余应力且满足初始应力对称性条件的弹性生长自由能函数和力电耦合生长自由能函数，推导多场耦合的组织生长本构关系，开展生物组织的力电耦合生长演化过程预测，采用非线性力电耦合理论和增量理论，对生物组织生长和形貌演化开展力电耦合调控研究。通过本项目研究，进一步发展和完善现有组织生长演化预测的连续介质力学理论体系，学术价值明显；同时也可为延缓衰老、病变组织生长监测、疾病诊断、及组织工程提供可参考的理论依据，发挥力学在生物医学和医疗健康领域的作用。

项目研究了组织生长和形貌演化的弹性生长模型及其力电调控机制，主要成果包括：建立了考虑初始应力的弹性生长本构关系和修正乘法分解模型，考察了初始应力和各向差分生长比对组织生长应力及表面失稳形貌的调控规律，针对管状双层软组织及核壳球结构组织的生长及表面失稳形貌演化过程，开展了初始应力调控规律的理论建模分析，并引入初始几何不相容条件构造具有初始应力的水凝胶双层管，通过溶胀模拟生长和表面形貌失稳实验及有限元模拟，验证了理论模型的有效性；针对生物组织生长过程受电场影响的生理现象，建立了力电耦合体生长理论模型，从理论上解释了管状软组织生长和失稳形貌的力电耦合调控机制。本项目研究成果揭示了初始应力及力电耦合效应对组织生长和形貌演化的影响规律，提出的考虑初始应力的修正乘法分解模型，突破了传统乘法分解模型中初始构型虚拟零应力的局限性，为组织生长提供了可靠的理论预测和调控手段。依托本项目，指导博士研究生6名、硕士研究生2名，发表SCI收录论文19篇，授权国家发明专利9项，PCT国际专利检索2项，举办国际国内学术会议5次，研究成果被Physics Today选为Back Scatter进行了专题报道，博士生杜洋坤同学的学位论文《软组织体生长理论的修正扩展及其在生物健康监测中的应用》获浙江大学优秀博士学位论文提名奖和浙江省优秀博士学位论文提名奖。