A comparison of surface roughness analysis methods applied to urinary catheters

The resolution of conventional tactile surface roughness measurement is limited by the stylus tip radius since the stylus can only make a good contact in a valley wider than tip diameter. A 3D scanning electron microscopy (SEM) technique, namely SEM stereo-imaging, was used to reconstruct the surface features of 12 different catheters to validate tactile measurement results. It is demonstrated that if the surface roughness and the stylus tip differ by one order of magnitude, the results of the tactile measurement may not be reliable.