To prepare a C. citratus oil coated silicone rubber surface, a layer ofhypromellose ointment containing the oil was placed in a sterile Petridish and a piece of sterile silicone rubber sheet was placed on top ofthat. Following this, gentle pressure was applied onto the siliconerubber sheet to let the ointment stick onto the material. Subsequently,the coated silicone rubber sheet was gently taken out of the Petri dishand placed inside sterile 6 well-plates for the biofilm formation experiments. The coating thickness was estimated by Optical CoherenceTomography (OCT) (Ganymade, Thorlabs INC., Munich, Germany) andwas found to be approximately 0.3 mm.