Effect of working gas composition in medical needle sharpening by ion beam sputtering

The sharpness of cutting edges and apexes is crucial in the performance of various medical devices. A method of medical needle finishing, consisting of large area ion beam sputtering, is introduced and studied. Significant deburring, edge sharpening and surface modification of the needles is demonstrated by an experiment. The influences of working gas composition and total ion fluence on the resulting needle properties are emphasized. It was shown that the utilization of an Ar/dry air mixture (37/6) resulted in a significant improvement in surface morphology, compared to pure Ar sputtering. The effect of gas composition is discussed in terms of concurrent material sputtering and chemisorption of reactive species. Needle sharpening aspects studied using microscopy techniques were confirmed by measuring the force required to push a needle through a plastic film. The puncture force of an as-grinded needle was reduced by ∼50% by means of the reported method.