Study on Fast Needle Puncture to Reduce Pain

This study focused on evaluating different COFs (coefficient of friction) between needles and skin generated by different diameters, surface treatments, needle loads, and puncturing speeds of syringe needles. The goal of this study is to design a COF measurement device and to find a way to reduce the skin pain caused by needles in order to improve the quality of life of those who need frequent blood collections and injections. The result of synchronized measurement of high speed camera and load cell indicates that the distance, instantaneous speed, average speed, friction force and COF are proportional to diameter of syringe needles. The aforementioned experimental result also indicates the maximum COF is at diameter of 1.2 mm, followed by 0.8 mm and 0.5 mm. That is, a needle with a larger diameter will produce greater friction and COF during passage through human skin, resulting in greater pain. The summary of experimental results indicates that the higher needle puncturing speed, the smoother needle surface (for example, the coated surface), the less needle load, and the smaller needle diameter will result in smaller COF such that it can reduce the pain caused by friction during needle puncturing. The key points of the experimental result are summarized as below: 1.With needle diameter of 1.2 mm and bare needle load of 100 g, the µs (the maximum static coefficient of friction) is reduced by 60% (0.89: 0.36) and the µk (the dynamic friction) is reduced by 61% (0.80: 0.31) when the needle puncturing speed is increased from 0.01 m/s to 1.35 m/s. Note also that µs is always greater than µk, 2.With needle diameter of 1.2mm under puncturing speed 0.01m/s, the µs and µk reduced by 9% (0.65: 0.59) and 5% (0.57: 0.54) respectively, when the bare needle load is decreased from 200g to 100g. 3.With needle load of 100g under speed 0.01m/s, µ s is reduced by 20% (0.59: 0.47) and $\mu k$ is reduced by 24% (0.54: 0.41) when the needle diameter is decreased from 1.2 mm to 0.5 mm. 4.With the needle diameter of 1.2mm under speed 0.0 1m/s and load 100g, the comparison between bare needle and coated needle indicates that µs is reduced by 32% (0.65: 0.44) and µk is reduced by 30% (0.57: 0.40).