Characterization of ESD Risk for Wearable Devices
The core difference between the posture assumed for IEC 61000-4-2 human metal discharge and a discharge to a wearable device is the impedance between the charged body and the grounded structure discharged to. Especially for a waist-worn device, a larger portion of the body is close to the grounded structure; thus the geometry forms much lower impedance which will lead to higher currents. Despite the variability for the air discharge, in most cases, the current will be higher than 3.75 A/kV as specified for contact mode electrostatics discharge (ESD) calibration. Even for the most slowly rising discharges having a spark length equal to the value given by Paschen's law, a 10 kV ESD from the waist will surpass 37.5 A for a waist-worn metal part discharged (e.g., to a door frame). Modeling the wearable device discharge provides predictions on the current derivative and the transient field a wearable device is subjected to. Observed failure levels of a wearable electronic device and comparing discharges according to the IEC 61000-4-2 test standard against discharges from the device while wearable showed that the IEC set-up may be insufficient to ensure the robustness of the wearable devices.
J. Zhou et al., "Characterization of ESD Risk for Wearable Devices," IEEE Transactions on Electromagnetic Compatibility, vol. 60, no. 5, pp. 1313-1321, Institute of Electrical and Electronics Engineers (IEEE), Oct 2018.
The definitive version is available at https://doi.org/10.1109/TEMC.2017.2780056
Electrical and Computer Engineering
Electromagnetic Compatibility (EMC) Laboratory
Keywords and Phrases
Electric Current Measurement; Electric Discharges; Electric Grounding; Electric Sparks; Electron Devices; Electrostatic Devices; Electrostatic Discharge; Electrostatics; Hidden Markov Models; Laser Optics; Markov Processes; Models; Standards; Current Derivatives; Electronic Device; Grounded Structures; IEC Standards; Impedance Measurement; Soft Failure; Transient Fields; Wearable Devices; Wearable Technology; Modeling; Sparks
International Standard Serial Number (ISSN)
Article - Journal
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