Examination of needle surface corrosion in electroacupuncture

Background: Electroacupuncture (EA) is a modern form of acupuncture therapy where stainless steel acupuncture needles are used as percutaneous electrodes to apply electrical stimulation. The concern about electrolytic corrosion of needles during EA has not been conclusively addressed. Aim: To examine whether corrosion of stainless steel acupuncture needles occurs after EA to establish the safety profile of this therapy. Methods: The study comprised four EA sessions on healthy participants mimicking a common clinical practice, with needle surface examinations conducted immediately after each session. Used acupuncture needles that did not undergo electrical stimulation and unused needles taken from the original package were also examined as control comparisons. Two commonly used types of single-use, silicone-coated, stainless steel needles were selected for the experiment. The ES-160 digital acupunctoscope (a charge-balanced electric stimulator) was used to deliver electrical stimulation, and an oscilloscope was used to record the waveforms and electric currents. All needles were sterilised before examination by a scanning electron microscope (SEM), where images of needle tips and shafts were taken for further analysis. Results and conclusions: 32 needles were examined under the SEM. As the main findings, the SEM images showed the surface finish, burr attachments and surface characteristics of needle samples. No evidence of electrolytic corrosion was detected on any needle that underwent electrical stimulation for 30 min delivered by a charge-balanced acupunctoscope in healthy participants. The choice of a charge-balanced acupunctoscope is recommended to avoid any potential corrosion of needles in EA clinical practice.