Characterization of Biofilm Wrinkles Based on the Composite Bilayer Model

The study of the biofilm mechanical stability is important in the fields of biomedical and environmental engineering. In this paper, we present an innovative simplified bilayer model, which is obtained based on a simplification of the complex four-layer model. We simplify the model and reduce the computational complexity by ignoring the top layer of the biofilm and treating the middle layer and the substrate layer as a spring system connected in series. In finite element analysis, we used a simplified two-layer model to simulate the bending behavior of biofilm wrinkles and found the influence of elastic modulus ratio (Ef/Es) and biofilm thickness (h) on biofilm wrinkles and critical stress ( $\epsilon$ ). We simulated the wrinkle morphology changes of biofilm in regions II and III on three low, medium, and high agar substrates, and compared the simulated wrinkle wavelengths with experimental data for verification, providing a new perspective for understanding the mechanical behavior of biofilms.