Increasing demand for fully autonomous wireless sensors to service the emerging technologies of the internet of things, remote and real time monitoring of vulnerable environments or self-sensing smart structures is driving a requirement for efficient and novel methods of energy harvesting. The sensor's data communication has a substantial power requirement that presents a serious constraint upon the number of sensors, and their capability. Our primary aim is to realise innovative Lead-free electromechanical energy harvesters; these will be easily installed, to power, in a clean and low-cost manner, autonomous wireless sensing devices thereby eliminating batteries and human intervention: This will revolutionise sensor applications whilst simultaneously reducing chemical waste. This is timely as in current solutions battery replacement is either logistically impossible or too expensive and batteries carry a toxic chemical cost. Solar panels have the environmental drawback of using toxic materials. In our vision of future sensor technology, with our vibration energy harvesters (VEH) as their primary power source, a battery, will become unnecessary, and their associated chemical waste will no longer occur, and these sensors will become truly autonomous. The harvester's mechanical core will draw on advanced multiresonator designs, integrating Lead-free piezoelectric patches enhanced by the unique wave control capacities of resonant elastic metamaterials. Currently microVEH, though promising, suffers due to frequency mismatch: We have the ambition to bridge the gap between different scales by leveraging the potential of metamaterials. This will dramatically increase the energy available for harvesting, and operational bandwidth. For electronic applications the integration of rectifiers in the circuitry will allow for the full exploitation of the multiresonant design.