SEM images recorded using various accelerating voltages on the same area of an IL-treated biofilm specimen. The IL used was 1% [Ch][Lac]. The accelerating voltages were (a) 1 kV, (b) 5 kV, (c) 10 kV, and (d) 20 kV. At an accelerating voltage of 1 kV, it was difficult to focus the image. At 5 kV, the bacteria and biofilm outlines were observed clearly. Scale bars = 5 μm.