Determination of biofilm mechanical properties from tensile tests performed using a micro-cantilever method

Abstract

Recently, a micro-cantilever method was introduced for measuring the ultimate tensile strength of intact bacterial biofilms. Herein, is reported the analysis of the video files from the testing of a 4-day-old Staphylococcus epidermidis biofilm to determine the elastic modulus, toughness, and failure strain. Elastic modulus (1270±280 Pa) was within the range of previously reported values (17–6000 Pa). The high failure strains (240±16%) indicate the substantial ductility of bacterial biofilms. In addition, the toughness of the biofilm sample was determined from the area under the stress–strain plot (2.8±0.44 kJ m⁻³). Thus, it was demonstrated that the micro-cantilever test video files can be used for the determination of other mechanical property parameters besides ultimate tensile strength.

Keywords:

• micro-cantilever method
• elastic modulus
• toughness
• failure strain

Acknowledgements

This work was supported by a National Science Foundation grant (Project award number 0728550).