title: Interfacial separation of a mature biofilm from a glass surface - A combined experimental and cohesive zone modelling approach.
abstract: A good understanding of the mechanical stability of biofilms is essential for biofouling management, particularly when mechanical forces are used. Previous biofilm studies lack a damage-based theoretical model to describe the biofilm separation from a surface. The purpose of the current study was to investigate the interfacial separation of a mature biofilm from a rigid glass substrate using a combined experimental and numerical modelling approach. In the current work, the biofilm-glass interfacial separation process was investigated under tensile and shear stresses at the macroscale level, known as modes I and II failure mechanisms respectively. The numerical simulations were performed using a Finite Volume (FV)-based simulation package (OpenFOAM®) to predict the separation initiation using the cohesive zone model (CZM). Atomic force microscopy (AFM)-based retraction curve was used to obtain the separation properties between the biofilm and glass colloid at microscale level, where the CZM parameters were estimated using the Johnson-Kendall-Roberts (JKR) model. In this study CZM is introduced as a reliable method for the investigation of interfacial separation between a biofilm and rigid substrate, in which a high local stress at the interface edge acts as an ultimate stress at the crack tip.This study demonstrated that the total interfacial failure energy measured at the macroscale, was significantly higher than the pure interfacial separation energy obtained by AFM at the microscale, indicating a highly ductile deformation behaviour within the bulk biofilm matrix. The results of this study can significantly contribute to the understanding of biofilm detachments.
authors.affiliation: School of Mechanical and Materials Engineering, University College Dublin (UCD), Belfield, Dublin 4, Ireland.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Safari
authors.affiliation: Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Zagreb, Croatia.
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Tukovic
authors.affiliation: School of Mechanical and Materials Engineering, University College Dublin (UCD), Belfield, Dublin 4, Ireland.
authors.forename: Philip
authors.initials: P
authors.lastname: Cardiff
authors.affiliation: School of Chemical and Bioprocess Engineering, University College Dublin (UCD), Belfield, Dublin 4, Ireland.
authors.forename: Maik
authors.initials: M
authors.lastname: Walter
authors.affiliation: School of Chemical and Bioprocess Engineering, University College Dublin (UCD), Belfield, Dublin 4, Ireland.
authors.forename: Eoin
authors.initials: E
authors.lastname: Casey
authors.affiliation: School of Mechanical and Materials Engineering, University College Dublin (UCD), Belfield, Dublin 4, Ireland. Electronic address: alojz.ivankovic@ucd.ie.
authors.forename: Alojz
authors.initials: A
authors.lastname: Ivankovic
mesh_terms: D018441:Biofilms; D005898:Glass; D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force; D008962:Models, Theoretical; D013314:Stress, Mechanical; D013499:Surface Properties
keywords: Atomic force microscopy; Biofilm; Cohesive zone model; Interfacial failure; JKR contact model