“…Compared to the conventional Vickers-indentation-based fracture toughness test method (VIF) and other currently available microscale mechanical testing methods, e.g., single and double cantilever testing [31], the micro-pillar test method offers several advantages including its ease of application. Note, post-test measurement of the crack length, a factor that is critical for VIF and highly dependent on the image acquisition, is not necessary [32,33]. Any potential residual stress, that might be induced by stoichiometric gradients or differences in thermal expansion in the case of a thin film on a substrate, is fully released and do not affect the test if the pillars have an aspect ratio of height to diameter between 1 and 4 [34].…”