ABSTRACT
Micro-energy harvesting has a crucial role in the modern wireless communication technology including the Internet of Things and cloud computing concepts of Industry 4.0. It involves capturing and converting energy from various ambient sources to power small-scale electronic devices and systems. Industry 4.0 enables efficient data collection, analysis, management, and integration of these systems into industrial processes and grids, ultimately contributing to sustainability, cost savings, and improved overall efficiency in energy utilization. In comparison with periodically replaceable energy sources, green energy alternatives are quite useful. Abundantly available ambient sources such as heat, vibration, and sound energy around the machinery and structures in factories can be exploited to obtain electrical power. A specially designed cantilever oscillator with embedded piezoelectric (PE) or electromagnetic (EM) circuits is often employed for such energy harvesting. When the ambient vibration frequencies come close to the natural frequency of the harvester beam, the resulting large vibration amplitudes due to resonance generate considerably large electrical power output. However, it is difficult to tune the harvester with the surrounding vibrations as most ambient vibrations are of low-frequency signals. To enhance the circuit output, several modifications in the design, such as adding nonlinearities into the system or parametric/stochastic resonances or multiple resonance states, are employed in the design. The present chapter reports some developments in such power enhancement approaches using hybrid PE and EM principles of energy conversion. Structural response and power output evaluations of these harvesters are discussed by using some basic dynamic models. The optimized design of a harvesting system for power enhancement is also described. General laboratory-level experimental testing is explained and future research outlook is given in the conclusion.
