Schematic describing the four primary techniques to evaluate barrier layer performance. A. Water vapor transmission rate determination using the Ametek MOCON platform or a calcium test, B. Visual degradation studies using dissolvable metals such as magnesium, C. Electrochemical impedance spectroscopy to determine water uptake or delamination, and D. Device performance rapid soak tests at elevated temperatures. A1, calcium test. Reproduced with permission.[481] Copyright 2016, Elsevier. B, visual Mg degradation test. Reproduced with permission.[463] Copyright 2017, John Wiley and Sons. C, electrochemical impedance spectroscopy. Reproduced with permission.[449] Copyright 2020, American Chemical Society. D, rapid soak test. Reproduced with permission.[450] Copyright 2018, American Chemical Society.