Development of a multi-physics biofilm model incorporating biofilm mechanical and structural characteristics from multi-dimensional imaging datasets acquired by means of optical coherence tomography

本项目的目的是详细研究水动力和营养条件对生物膜聚集体中尺度行为的影响。通过独特的实验和计算优势的结合，将开发一个全面的生物膜模型，该模型能够可靠地预测生物膜的生长、结构、与周围流体的相互作用以及在广泛不同条件下的脱离。中尺度的光学相干层析成像(OCT)和微观尺度的激光共聚焦扫描显微镜(CLSM)等成像技术将提供在确定的养分有效性和流体动力学条件下生物膜发育和内部结构的必要信息。氧敏感光电探测器将提供有关代谢活动的信息。然后，这些数据将用于建立和校准先进的连续生物膜模型。由于生物膜材料的性质决定了它的行为和与周围流体的相互作用，因此对生物膜的物理特性的透彻了解是至关重要的。因此，将开发一种成像方案，该方案将允许在中尺度上可视化生物膜结构，并通过在3D中评估生物膜对改变的流动条件的时间分辨响应来表征其特性。这些实验数据将通过数字图像处理的方式传输到计算模型中，然后将成为使用逆分析方法确定生物膜材料特性的基础。从均质材料的假设出发，接下来还将考虑生物膜特性的(非均质)分布，以便能够更真实地模拟生物膜的行为。作为下一步，将开发一个考虑不同时间尺度的可靠的生物膜生长模型。同样，联合实验-建模工作对于确定相关因素(例如，养分可获得性和机械应力)并量化其对生物膜生长的影响至关重要。为了估计生物膜的粘附力和粘附力，将进行分离实验。这些信息将再次用于计算模型的进一步开发和校准。通过比较模拟和实验观察的生物膜结构，将评估得到的生物膜模型的质量，包括流体-结构相互作用(FSI)、基质转移、生长和脱落。特别是，模型的预测能力将通过将其应用于未知场景来评估，例如真实的废水生物膜或改变的水动力负荷。然后，该模型将被用来在不一定通过实验实现的大范围不同条件下获得更多关于中尺度生物膜动力学的见解。通过这些手段，将采取有系统地制定生物膜控制/优化战略的第一步。

The objective of this project is to investigate in detail the influence of hydrodynamic and nutritional conditions on the mesoscale behavior of biofilm aggregates. By means of a unique combination of experimental and computational strengths, a comprehensive biofilm model will be developed that enables the reliable prediction of biofilm growth, architecture, interaction with the surrounding fluid, and detachment for a wide range of different conditions. Imaging techniques such as optical coherence tomography (OCT) for the mesoscale and confocal laser scanning microscopy (CLSM) for the microscale will provide the necessary information on biofilm development and internal structure at defined nutrient availability and hydrodynamic flow conditions. Oxygen sensitive optodes will provide information about the metabolic activity. These data will then be used for setting up and calibrating an advanced continuum biofilm model. Since biofilm material properties govern its behavior and interaction with the surrounding fluid, a thorough knowledge of the physical characteristics of biofilms is essential. Therefore, an imaging protocol will be developed, which will permit to visualize the biofilm structure at the mesoscale and characterize its properties by assessing the time resolved response of the biofilm to altered flow conditions in 3D. These experimental data will be transferred to the computational model by means of digital image processing and will then be the basis for the determination of biofilm material properties using an inverse analysis approach. Starting from the assumption of a homogeneous material, a (heterogeneous) distribution of biofilm properties will also be considered in the following to enable a more realistic modeling of biofilm behavior.As a next step, a reliable model for biofilm growth accounting for the different time scales involved will be developed. Again, a joint experimental-modeling effort is essential to identify relevant factors (e.g., nutrient availability and mechanical stress) and quantify their effect on biofilm growth. To estimate the cohesive and adhesive strength of the biofilm, detachment experiments will be conducted. This information will again be utilized for further development and calibration of the computational model.The quality of the resulting biofilm model including fluid-structure interaction (FSI), substrate transfer, growth, and detachment will be assessed by comparing simulated and experimentally observed biofilm structures. In particular, the predictive capability of the model will be evaluated by applying it to unknown scenarios such as real waste water biofilms or altered hydrodynamic loading. The model will then be utilized to gain more insights into mesoscale biofilm dynamics for a wide range of different conditions not necessarily realized experimentally. By these means, first steps towards systematically developing strategies for biofilm control/optimization will be taken.