 Abstract here, we reviewed the state-of-the-art strain sensors that can be used in flexible, printed, and hybrid microelectronics. These sensors were categorized into four mechanisms of optical phenomena, diffraction, reflection, interference, and photonic crystal, fluorescent mapping, mechanochromism and mechanoluminescence, moire effect, and thermal imaging. Additionally, the sensors operating principles, sensitivities, dynamic windows, and spatial resolutions were discussed. Three types of strains, uniaxial, biaxial, and multiaxial, with sub-categories in strain mode, tensile and compressive, and uniformity, isotropic and anisotropic, were also summarized. Finally, three potential applications and markets of healthcare and biomedical engineering, human motion detection, sports science, and roll-to-roll manufacturing were provided as a stepping stone for those working in this field. This article was authored by Padmanapundra Kaksha Pancham, one HSI NGU, Anupam Mukherjee, and others. We are article.tv, links in the description below.