Modelling of Cutting Force and Deflection of Medical Needles with Different Tip Geometries

AbstractInsertion of needle into tissue is influenced by the cutting edges and the needle tip geometry. In this paper, we aimed at investigating the relationship between the insertion forces and cutting edge geometry and general mathematical models of included and inclination angles for two different needle configurations. Two new geometries, one with parabolic cut and other with parabolic surface, cut with two bevel planes have been proposed along with the corresponding mathematical models to improve the cutting edge properties. Results show that parabolic needles after cutting with bevel planes have significantly improved cutting edge properties and are better than the other common needle configurations such as bevel cut. Simulation studies predicted that the deformation and stresses are slightly higher for proposed needle tip geometries than currently available topologies. However, the advantage of included and inclination angles reduce insertion forces thus optimization of medical needle design for the selected tip geometries is a trade-off between insertion forces and deflection in needle

Investigation on bacterial adhesion and colonisation resistance over laser-machined micro patterned surfaces

Micro–nano patterns created directly over solid surfaces to combat microbial activity help in preventing hospital-acquired infections. This Letter is focused on defining surface topologies by laser patterning over solid surfaces. Studies on designing surface topologies and bacterial culture have been carried out and the feasibility of micro scale features in restricting bacterial growth has been investigated. The effects of the engineered roughness index and contact angle are discussed. Contact angle measurement over patterned surfaces using a novel computer vision-based technique is demonstrated and the effect of contact angle on bacterial adhesion has been presented. The results obtained show that the designed micro scale geometries can effectively reduce the growth of bacteria on the said surfaces