Present energy harvesting solutions, based on metamaterials, have been proposed by the scientific community with the vast majority remaining at the proof-of-concept level, without incorporating realistic design conditions. At this colloquium we aim to bring together world-leading, complementary expertise in the theory, simulation, manufacturing, and experimental realisation of metamaterials and architected materials to define novel energy harvesting solutions for next-generation self-powered sensors. Such a colloquium would sow the seeds for a new global network between applied mathematics, physics, and engineering to address specific issues related to vibration-based energy harvesting for Internet of Things (IOT) sensors.