The present study introduces an advanced multi-physics and multi-scale modeling approach to investigate in silico colon motility. We introduce a generalized electromechanical framework, integrating cellular electrophysiology and smooth muscle contractility, thus advancing a first-of-its-kind computational model of laser tissue soldering after incision resection. The proposed theoretical framework comprises three main elements: a microstructural material model describing intestine wall geometry and composition of reinforcing fibers, with four fiber families, two active-conductive and two passive; an electrophysiological model describing the propagation of slow waves, based on a fully-coupled nonlinear phenomenological approach; and a thermodynamical consistent mechanical model describing the hyperelastic energetic contributions ruling tissue equilibrium under diverse loading conditions. The active strain approach was adopted to describe tissue electromechanics by exploiting the multiplicative decomposition of the deformation gradient for each active fiber family and solving the governing equations via a staggered finite element scheme. The computational framework was fine-tuned according to state-of-the-art experimental evidence, and extensive numerical analyses allowed us to compare manometric traces computed via numerical simulations with those obtained clinically in human patients. The model proved capable of reproducing both qualitatively and quantitatively high or low-amplitude propagation contractions. Colon motility after laser tissue soldering demonstrates that material properties and couplings of the deposited tissue are critical to reproducing a physiological muscular contraction, thus restoring a proper peristaltic activity.

翻译：本研究提出了一种先进的多物理场、多尺度建模方法，用于在硅基环境中研究结肠运动。我们建立了一个广义的机电耦合框架，整合了细胞电生理学与平滑肌收缩性，从而首次构建了用于模拟切除术后激光组织焊接的计算模型。该理论框架包含三个核心要素：一是微结构材料模型，基于四族纤维（两族主动导电纤维与两族被动纤维）描述肠壁几何构型及增强纤维的分布特征；二是基于全耦合非线性现象学方法的电生理模型，用于描述慢波传播过程；三是热力学一致性力学模型，通过超弹性能量贡献描述不同载荷条件下的组织平衡状态。采用主动应变方法，利用各主动纤维族变形梯度的乘法分解描述组织机电行为，并通过交错有限元方案求解控制方程。依据当前最优实验证据对计算框架进行参数标定，通过大量数值分析，将数值仿真得到的测压曲线与临床患者实测数据进行对比验证。结果表明，该模型能定性和定量地复现高/低幅度传播性收缩。激光组织焊接后的结肠运动证明，沉积组织的材料特性及其耦合关系对实现生理性肌肉收缩、恢复正常蠕动功能具有关键作用。