Insertion force is due mainly to the effects of cutting and friction, whereas retraction force is due primarily to friction. We also used numerical simulation to elucidate the influence of COF on the performance of the needles.įigure 2 presents the insertion/retraction force measurement results in rubber and pig muscle. In this study, we applied TFMG coating to 304 stainless-steel (SS304) dental needles (size 31 G) and compared the results with conventional crystalline metallic coating, pure titanium (Ti) and ceramic coating (titanium nitride, TiN) with regard to the surface properties of the devices. In previous studies, thin film metallic glass (TFMG) has been shown to provide effective antibacterial properties 14, 15 as well as sharpness and durability when applied to surgical blades 14, 16. Researchers have recently reported that MGs exhibit excellent biodegradability and biocompatibility 11, 12, 13. This makes MGs a promising alternative candidate for biomedical applications 10. A new class of metallic glass (MG) exhibit high strength, elasticity and good corrosion and wear resistance due to a lack of long-range atomic periodicity 8, 9. However, DLC is brittle and has high internal compressive stress, leading to the poor adhesion to the metallic substrates 7. DLC coatings on the needles used in ophthalmic surgery have been shown to reduce the friction involved in penetrating the cornea of pig eyes by about 30% 6. However, the effectiveness of these coatings decreases with use, particularly when used for the sewing of skin.ĭiamond-like carbon (DLC) coatings have been applied in biomedical applications, to take advantage of their exceptionally low friction properties and biocompatibility 5. The surface of most medical needles is coated with silicone fluid lubricants to reduce friction and thereby reduce the amount of force required for insertion. Few studies have reported on the coatings used in the preparation of needles for medical applications, despite their importance on the performance of the devices. Insulin needles and dental needles are examples of fine needles used for individual and clinical use, respectively 3, 4. Fine needles with a smaller gauge size are becoming increasingly popular for their ability to reduce the pain associated with needle insertion. The force necessary for penetration can be affected by many factors, such as the geometry of the point, the method of insertion and characteristics of the tissue. The interaction between the needle and tissue greatly influences the discomfort associated with the use of these devices 1, 2. Syringe needles are common medical devices used in the transdermal delivery of drugs.
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