Evaluating Characteristics of Electrostatic Discharge (ESD) Events in Wearable Medical Devices: Comparison with the IEC 61000-4-2 Standard

Electrostatic discharge (ESD) malfunctions in wearable medical devices have resulted in injuries and deaths. The U.S. Food and Drug Administration (FDA) recommends medical device manufacturers to qualify the electromagnetic compatibility of their products according to the IEC 60601-1-2 collateral standard, within which the IEC 61000-4-2 standard is the recommended ESD immunity test method. This paper shows that the IEC 61000-4-2 standard does not provide adequate immunity for wearable medical devices, due to the differences between the test setup and the real usage. The peak and maximum time derivative of the ESD current and transient magnetic fields were measured during realistic discharge scenarios, where a metal piece, in lieu of a wearable device, was worn around human hand or waist. At five voltage levels from 2 to 10 kV, the peak currents and their maximum time derivatives for realistic discharge scenarios were larger than the most severe discharges obtained from the IEC 61000-4-2 test configuration. This discrepancy between the current results from the IEC 61000-4-2 standard setup and the realistic discharge scenarios indicates that the ESD immunity standard for wearable devices needs to be changed with realistic test configurations, to prevent device malfunctions that can subsequently jeopardize patient safety.