Surface energy modification method using x-ray synchrotron irradiation for controlling bacterial adhesion on biodegradable-polymer structures for bacteria-flagellated microrobots

Bacteria-based biomedical microrobots have been proposed to achieve effective localized drug delivery. To enhance a directional locomotion of bacteria-attached microsystem, structures with selective bacterial adhesion are necessary. Having different surface morphologies of microstructures is beneficial for selective attachments of bacteria. In this paper, a surface energy modification method for controlling bacterial adhesion on biodegradable-polymer structures is presented. This is achieved by controlling exposed doses of x-ray synchrotron irradiation. To calculate the x-ray exposure time for varying the surface morphology of the biodegradable polymeric devices, the equation for exposed dose is derived. The contact angles of different surfaces are measured, and the corresponding surface energies are calculated to verify the modification of the surface morphology. As a result, the surface energy increases with the increment of the exposed dose to the biodegradable-polymer. The developed surface energy modification method is suitable for modifying the polymeric surface without additional physical/chemical treatments. The fabricated cubic structures with different surface morphologies can be used for effectively flagellating bacteria on selective surfaces for directional locomotion.