Cleanability of Metal Surface Finishes Found in Medical Devices and the Environment of Care.

The surface finish of reusable medical devices often is a consideration during design, with attention paid to utility, aesthetics, and cost. To study the cleanability of metal surfaces of varying roughness and finish, soil made of bovine blood and egg yolk was placed on nickel alloy surface of varying average roughness (Ra) values (nominal values of 2-500 μin) and finishes (lapped, ground, milled, profiled, and shape turned). A commercially available wipe consisting of quaternary ammonium compound and less than 20% alcohol was applied for a total of eight wipe cycles to remove the soil. The wipe was applied in both horizontal and vertical directions. Evaluation methods for cleanliness include visual inspection and adenosine triphosphate (ATP) measurement. Rougher surfaces above nominal Ra of 250 were found to have higher ATP readings when wiped in both horizontal and vertical directions. In addition, different surface finishes have different cleanabilities despite similar nominal Ra. To ensure optimal cleaning, surfaces should be cleaned in multiple directions. In the future, similar studies will be coupled with efficacy studies and surfaces made with other materials will be investigated.