Vibration-Based Energy Harvesters: New Ways to Scavenge Energy

The need for wirelessly connected systems is heavily anticipated in today’s smart world since it is necessary for such a world to quickly transform into a global market through them. Utilizing mobile energy sources is crucial due to technological advancements such as wireless sensor networks (WSNs) [1], micro-electromechanical systems (MEMS) [2], and the Internet of Things (IoT). These requirements can be met using battery connectivity, cable connectivity, non-regenerated energy sources, and so forth. However, there is a growing need to develop alternative effective energy storage methods due to certain technical shortcomings, such as current leakage in batteries (in cases of both used and unused batteries), electricity resistance, practical challenges in cases of connections made through a wire, and so forth. The barriers to using the currently available energy sources include personnel shortages, regular maintenance, limited life cycles, limited energy availability, and delays in disposing of associated waste. A creative approach for energy generation from the available environmental sources has been developed to supplement the current technological demands without polluting the environment in order to overcome all of these obstacles. There are various ways to collect energy near to an area without compromising the area’s sanitation or ecological health. Therefore, different energy sources such as wind, solar, geothermal, hydropower, and vibration, among others, can be taken into consideration to generate power in light of environmental concerns and the current energy crisis. Both solar and vibration sources of energy are superior study focus areas when taking into account several advantageous features such as technological viability, cleanliness, scope for improvement, maintenance costs, and so forth. Vibration energy sources, however, are ideal for upcoming studies as we examine the technology maturity element. Small-scale devices as well as energy-consuming equipment for transportation, infrastructure, and human movement may benefit from this.

Vibration energy harvesting (VEH) is a method for recovering energy from unwelcome environmental vibrations. The movement of vehicles on bridges and the operation of numerous types of machinery in factories and on construction sites cause significant vibrations. This leftover energy that is released into the environment might be thought of as a lost source of potential energy. Electrical energy can be captured by utilizing intelligent materials and implementing various energy harvesting strategies. Such energy is regarded as free energy because it is extracted from natural and industrial environments. Therefore, vibration is an attractive source of energy for small devices. It can be defined as nothing more than the accumulation of waves moving through solid objects. Vibration movement needs to be paired with a generator employing the seismic mass’s inertia in order to convert mechanical energy into electrical energy. Different transduction mechanisms have been developed for this purpose.

In contrast to micro energy harvesters (EHs), which are based on vibration and produce electricity in the mW and μW range, renewable energy harvesting plants employing wind, sun, etc., can produce power in the kW and MW range. The powering of wireless devices is the main problem, though. Vibration energy can be harvested as a sustainable energy source to power remote equipment. Because vibration energy generation is viable and eco-friendly with low installation and maintenance costs, it is the subject of current research. Health monitoring devices such as low-power wearable sensors, [3] electrocardiogram (ECG) machines, electronic microscopes, serum analyzers, glucometers, treadmills, magnetic resonance imaging (MRI) machines, and auto-analyzers can all function using the energy produced by these vibrations, and so forth [4]. Various strategies have been reported and reviewed in various studies to increase the capacity of power generation [5,6]. Although it has not yet been able to entirely replace batteries, there are several research studies being undertaken to lessen its risks to the environment, and current inventions will undoubtedly assist in enhancing the earlier research efforts, thus having a great impact on the sector.

This Special Issue discusses the evolution of the VEH mechanism, including its benefits and limitations as it has adopted new harvesting principles. The harvester’s weight and dimensions have been reduced through inventive design, the addition of proof mass to increase strain, and the introduction of nonlinearity [7,8,9]. A lot of work has been carried out in recent years to achieve effective power output. Finding a more reliable and efficient approach to create more voltage output from a low-frequency range is a significant challenge in today’s world. The majority of recent research investigations have focused on establishing ways to use various configurations and energy removal strategies to increase the conversion efficiency of EHs. With technological advancements, both large-scale VEH and small-scale EHs now provide viable solutions to the energy dilemma. When a wind load is applied, a building of a few stories can generate about a few hundred kW of power [10]. Such EHs are more durable, maintenance-free, and environmentally friendly than traditional storage options such as batteries.

Additional research on hybrid and broadband EH mechanisms is needed because different energy sources can be combined with vibration energy to form a hybrid system. This kind of system is more expensive and inefficient, however [7,11]. The harvesting of a considerable amount of energy from raindrops, soundwaves, flow-induced vibration, vortex-induced vibration, etc., should be prioritized in the future. Creating more efficient storage circuits and discovering novel materials should be the main objectives of future research. Such EHs are not only a viable battery replacement source but also a fresh approach to promoting efficient, self-sufficient, and versatile green energy sources.