Explanation for the area distribution shape given the uneven surface of the insert.

<p>A) Scanning electron microscope image showing the uneven surface of a sterile insert; B) Schematic of the uneven insert surface with biofilm growth, HDPE roughness height is commonly taken in modelling to be 20 μm, 80 μm was the greatest depth measured in Day 28 biofilms. Broken red lines indicate parts of an example area distribution curve and the corresponding cut through position of the biofilm.