Surface-blended texturing of medical needles for friction reduction using a picosecond laser

The success of percutaneous procedures depends on the accuracy of the medical needle insertion. Reducing the insertion force and using better needle visualization during needle insertion can reduce needle placement errors. Surface texturing is frequently used to create micro-features on medical needle's tip portion to improve the visibility in ultrasound-guided percutaneous procedures. However, these micro-features usually increase the friction between the needle and tissue because of stress concentrations. This paper explores a method for creating micro-features with blended edges on echogenic needles and studies the friction behavior between textured echogenic needles and phantom tissue to identify blended texture patterns that would minimize the friction during needle insertion. Laser surface texturing was used to create regular micro-circumferential channels and micro-corner-cube-like dimples along the needle's axial direction. Variations of the overlap in the feed direction were used to blend the edges of micro-channels and micro-dimples with different fillet radii. Both needles with regular and blended surface textures were experimentally investigated through needle extraction experiments from phantom tissue. It was found that the blended textured needles with large fillet radii exhibit a much better friction behavior.