ISO 20487:2019

Overview

ISO 20487:2019 specifies an in vitro test method to characterize the corrosion resistance of single‑use acupuncture needles when used for electro‑acupuncture. The standard defines a repeatable laboratory procedure using simulated body fluid (1× PBS), electrical stimulation and visual inspection to document corrosion behavior. ISO 20487 applies only to needles that conform with ISO 17218 and does not set pass/fail criteria or provide clinical safety guidance.

Key topics and technical requirements

• Test principle: Immerse needles in simulated body fluid, apply pulsed electrical current from a pulse generator to another needle, and inspect for corrosion at specified times.
• Test solution: 1× phosphate‑buffered saline (PBS) as the simulated body fluid.
• Pulse generator: Balanced biphasic waveform, output stability ±10%, frequency ≤ 1 000 Hz. Example RMS currents in the standard: (1 ± 0.1) mA, (3 ± 0.3) mA, (5 ± 0.5) mA.
• Recorder: Voltage resolution ≥ 1 mV and sampling frequency ≥ 200 kHz to measure voltage/current between electrodes.
• Temperature control: Simulated body fluid maintained at (37 ± 1) °C (water bath or equivalent).
• Resistor: Example 10 Ω with ±1 % tolerance (allowed range 1 Ω to 500 Ω depending on generator capacity).
• Geometry and positioning: Electrode spacing and immersion depths specified (ranges given in Table 1 / Annex A; e.g., inter‑electrode distance typically in the 10–30 mm range and immersion depths provided to millimetre tolerances).
• Test duration and sample size: Example electrical quantities and durations are provided; a minimum of five sets of needles per test condition is recommended.
• Reporting: Test reports must include details such as test date, needle type/size, test solution, pulse generator settings, measured voltage/current, electrode geometry, equipment models, result charts and any deviations.

Practical applications

• Compare corrosion performance across needle materials, coatings, designs or manufacturing processes used for electro‑acupuncture.
• Provide standardized laboratory data for R&D, quality engineering and premarket characterization of single‑use acupuncture needles intended for electrical stimulation.
• Support manufacturers, test laboratories and regulatory teams in documenting electrical corrosion behavior as part of product development and technical files.

Who should use this standard

• Medical device manufacturers of acupuncture needles and electro‑acupuncture systems
• ISO/IEC‑accredited test laboratories and quality assurance teams
• Regulatory affairs professionals preparing product dossiers or comparative technical data

Related standards

• ISO 17218 - Sterile acupuncture needles for single use (applicability prerequisite)
• IEC 60601‑2‑10 - Requirements for nerve and muscle stimulators (referenced for electrical definitions)
• IEC and ISO terminologies (IEC 60050, ISO online resources)

Keywords: ISO 20487, electro‑acupuncture, acupuncture needle corrosion, corrosion resistance test, single‑use acupuncture needles, simulated body fluid, ISO 17218.