MECHANICAL CHARACTERIZATION OF BACTERIAL CELLULOSE USING ATOMIC FORCE MICROSCOPY

• Main Author: Ebenezer Leonard, Frederick
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75853
• Institution: Institut Teknologi Bandung

<p align="justify">Bacterial cellulose (BC) is a biomaterial with unique physicochemical properties, characterized by an ultrafine reticulated structure, high crystallinity, high tensile strength, high hydrophilicity, and biocompatibility, making it suitable for applications ranging from food and medicine production to coatings and proton-conducting membranes for fuel cells. The mechanical characterization of BC would provide valuable insight into the material’s behavior under loading, enabling enhanced design, optimization and structural modification procedures; as well as serving as input for numerical simulations. Atomic Force Microscopy (AFM) is a method of measuring the mechanical properties such as the elastic modulus of biomaterials on a localized level with high resolution and range in addition to being non-destructive. The process involves indenting a sample locally using a microfabricated tip attached to the end of cantilever, calculating the force exerted on the tip and the indentation depth, and fitting the data over contact mechanics models. A functional AFM experimental setup has been assembled in ITB’s Nano Engineering Laboratory. It was observed that setup is prone to inaccuracies, however, yielding results that are several orders of magnitudes in difference compared to existing literature values. The sources of these problems were identified, and improvement of the AFM setup was carried out to enhance the accuracy and reliability of measurement results as part of this research. This involved a re-designing of the experimental setup, incorporating components including a high-resolution motorized stage, a helium-neon laser, and adjustable linear stages. The experimental procedures were also formulated in greater detail to increase repeatability and reproducibility. A derivation of relevant contact mechanics models for adhesive contact was also conducted for the purpose of data processing. The setup was then assembled, and then successfully utilized to measure the elastic modulus of BC samples. The results indicate that the modifications made has successfully improved the accuracy and reliability of the AFM experimental setup, procedures, and data processing methods, as the parameters of force acting on the AFM probe, indentation depth, and elastic modulus fall within the expected range.