50 years of nanomechanics: Scale-bridging mechanistic insights through the looking glass

Historical and recent advances in the field of nanomechanics, ranging from the early development of nanoindentation to recent advances in artificial intelligence- and machine learning-based characterization and modeling are covered in this article. Early advances were motivated by thin-film mechanics challenges driven by the microelectronics industry. In the ensuing years, different methodologies for probing mechanical properties at length scales relevant to a myriad of applications and materials systems have been developed, coupled with a variety of in situ testing methods that shed insights into new mechanisms. Built upon the knowledge base from nanomechanics, new mechanical metamaterials with otherwise unachievable material properties have been discovered, and new methods in testing and analyzing properties for extreme conditions have been recently reported. This article discusses the journey that the nanomechanics community has gone through over the past 50 years and shares the scale-bridging mechanistic insights through the looking glass.