Influence of acupuncture needle physical–chemical properties on needling quality

Objectives: This study analyzed the physical–chemical properties of three different brands of acupuncture needle, classified by acupuncturists as high (A), medium (B) and low (C) quality.Methods: Experienced acupuncturists, rated, in terms of perceived needling quality, three acupuncture needle brands as high (A), medium (B) and low (C) quality. Next, scanning electron microscopy (SEM) images of the tip and surface finish of the needles of each brand were analyzed. A mechanical test was developed and performed to evaluate the compressive force required to insert the needles through a smooth surface (silicon). In addition, X-ray fluorescence spectroscopy (XRF) and dispersive energy spectroscopy (DES) were conducted to analyze the material composition of the needles and presence of oxidation.Results: SEM images revealed that needle brands A and B presented a sharper tip and a more regular surface finish in comparison to brand C. In the insertion test, needle brands A and B had similar performance characteristics, with A requiring less force to penetrate the silicon device when compared to B, while C failed to penetrate the silicon and complete the test. The XRF analysis did not reveal any differences in material composition between the three brands. However, brand C exhibited particles embedded on the needle surface and DES confirmed oxidation.Conclusion: This study demonstrates that perceived needling quality by acupuncturists can be correlated with physical–chemical properties of the needles, especially those related to finishing quality of the tip and the surface of the needles.