**1. Introduction**

The chapter describes the results obtained in the field of energy harvesting (hereinafter referred to as EH, also known in the literature as power harvesting or energy scavenging). EH is a set of methods that allow obtaining electricity from sur-rounding sources, such as mechanical, thermal, solar, and electromagnetic energy, salinity gradients, etc. [1, 2]. Energy harvesting is the use of sources commonly found in the environment (the so-called background energy), which are undesirable and usually suppressed (e.g., noise, shocks and mechanical vibrations of devices and structures, electromagnetic smog, heat as a result of friction and combustion, current flow, cooling engines, etc.) or widely available (sunlight, wave energy, salinity differences, biochemical processes, e.g., in plants), as well as those related to human biology (movement, body heat, etc.), for example [3]. Currently, it is assumed that EH can be an effective source of "cost-free" energy (after omitting the installation costs) for powering low-power devices (e.g. electronic devices, sensor systems, etc.). Hence the growing interest in civil and military applications. The area of use of EH concerns numerous civil and military applications and includes such disciplines as medicine, transport (cars, aviation, pipelines), construction structures (bridges, buildings), mechanical structures, sports and rescue equipment, and many more.

Energy harvesting creates new opportunities today, especially in the field of the so-called self-powered microsystems. This is a consequence of the progress in the field of materials and technologies enabling the recovery of energy from the socalled background, i.e., from known sources, but so far omitted, which in turn was due to the low efficiency of transforming energy and the high cost of producing the necessary devices for this purpose (the so-called harvesters). The decreasing energy consumption of these microsystems is also of key importance, which causes power sources with a power of a mile or even microwatts to acquire practical significance and allow to eliminate traditional power systems using cable systems or batteries or accumulators. A particularly promising area of EH applications is systems for continuous monitoring of inaccessible structures or biomedical implants, as well as distributed systems for the detection of threats on large surfaces (e.g., fire protection systems in forests or detection of chemical or radioactive contamination). It is predicted that in the near future the power of EH systems will increase significantly and will also have significance in industrial power engineering. A better solution is to take energy from the surroundings unlimited in time. It is assumed that in the future EH will be a source of high-power energy by creating appropriately extensive harvester networks.

The paper describes the main directions of EH research based on magnetic transducers and characterized numerous own constructions, including harvesters with magnetic processing using the Faraday effect and modal resonance, with a large increase in voltage under the influence of coil movement, with a moving core of austenitic steel and magnetostrictive core. In particular, the construction, selected characteristics, and possible areas of harvester use are described. The issue of miniaturization of the harvester's construction and modification of the magnetostrictive core was undertaken. Magnetographic field measurements were also carried out outside the harvester. In addition, harvesters using mechanical shock and a dedicated inverter as well as a low-power electronic system were presented. A method has been developed for the use of harvesters and actuators for the wireless transmission of energy and information using Smart Ultrasonic Resonant Power System (the so-called SURPS system), an autonomous system of diagnostics of environmental and operating parameters' multi-degree-of-freedom (Multi-DOF) and the so-called wireless harvesting nodes. The directions for further research have been defined at the end.

Authors recommend energy-harvesting solution to go (**Figure 1**), as an indispensable development system in EH applications. This is a versatile device from Würth Elektronik demonstrating the capabilities of EH and power supplies based on various sources of energy. There are two built-in subassemblies for obtaining energy: using a thermoelectric effect and photovoltaic panel. The electronic site consists of a series of inverters dedicated to EH by linear technology and EFM32 Giant Starter Kit (Silicone Labs) equipped in addition to the microcontroller including LED display and light sensor. This harvester provides the option of changing the configuration of connecting [4–6] power sources. This solution shows a multitude of potential power options using EH, which will be described later in the work.

#### **1.1 Influence of smart materials on energy harvesting**

Describing smart magnetic materials and taking into account their properties, it is difficult not to undertake in their own research the issues of their application in

**35**

in the construction of harvester.

*Energy Harvester Based on Magnetomechanical Effect as a Power Source for Multi-node Wireless…*

the field of energy recovery (EH) and—as discussed further—wireless transfer of energy and information. It can even be said that the development of EH is possible thanks to the advances in science and engineering in the field of smart materials, including those stimulated by a magnetic field. From a wide group of them, materials with a giant magnetostriction (GMM) were considered to be particularly worth the attention and acceptance as an object of research in the field of EH. The GMM properties are crucial here. A typical example is Terfenol-D. Materials with gigantic magnetostriction can convert magnetic energy into mechanical and vice versa. Thanks to such properties, these materials can be used in the construction of sensors, actuators, and harvester. GMMs obtain much larger deformations (Terfenol-D up to 70 times) than traditional magnetostrictive materials, and to achieve this effect, not very high magnetic field strength H is required. There is also the opposite effect. Relatively small deformations generate relatively high magnetic field and therefore the induced electric current (in comparison with other ferromagnets). A very important feature of these materials is the wide range of operating temperature, as well as their low inertia (small hysteresis loop field), which facilitates their use in various conditions. The Curie temperature for Terfenol-D is 653–693 K, while the working temperature can reach up to 473 K. Examples of GMM applications in the EH range include aviation, road transport, stationary mechanical structures, medicine, sports and tourism equipment, and many more. The aim of the research is mainly to increase the efficiency of converting mechanical energy into electricity, miniaturization of harvesters, and reduction of their price. Solid Terfenol-D, despite its many advantages, has several disadvantages that hinder its wider application in the field of EH. A significant drawback is, above all, the high brittleness, which is associated with low tensile strength. Another limitation is eddy currents of considerable value, which limits the effective frequency of operation of the devices to several kilohertz. An important parameter is also the price of Terfenol-D, which remains at the level of 1 \$/1 g. These disadvantages are the reason for searching for new solutions. One of them is magnetostrictive composites, which can also be used

**1.2 Wireless energy and information transfer through energy harvesting**

The use of harvesters increasingly requires solving the problem of unconventional energy and information transfer by solid, liquid, and gas media. Therefore, it was considered important to characterize the state of the art in this area and undertake own research. Smart materials in this case can be effectively used for wireless energy and information transfer using ultrasonic vibrations. Most often,

*DOI: http://dx.doi.org/10.5772/intechopen.85987*

**Figure 1.**

*Energy-harvesting solution to go.*

*Energy Harvester Based on Magnetomechanical Effect as a Power Source for Multi-node Wireless… DOI: http://dx.doi.org/10.5772/intechopen.85987*

**Figure 1.** *Energy-harvesting solution to go.*

*A Guide to Small-Scale Energy Harvesting Techniques*

ment, and many more.

the installation costs) for powering low-power devices (e.g. electronic devices, sensor systems, etc.). Hence the growing interest in civil and military applications. The area of use of EH concerns numerous civil and military applications and includes such disciplines as medicine, transport (cars, aviation, pipelines), construction structures (bridges, buildings), mechanical structures, sports and rescue equip-

Energy harvesting creates new opportunities today, especially in the field of the so-called self-powered microsystems. This is a consequence of the progress in the field of materials and technologies enabling the recovery of energy from the socalled background, i.e., from known sources, but so far omitted, which in turn was due to the low efficiency of transforming energy and the high cost of producing the necessary devices for this purpose (the so-called harvesters). The decreasing energy consumption of these microsystems is also of key importance, which causes power sources with a power of a mile or even microwatts to acquire practical significance and allow to eliminate traditional power systems using cable systems or batteries or accumulators. A particularly promising area of EH applications is systems for continuous monitoring of inaccessible structures or biomedical implants, as well as distributed systems for the detection of threats on large surfaces (e.g., fire protection systems in forests or detection of chemical or radioactive contamination). It is predicted that in the near future the power of EH systems will increase significantly and will also have significance in industrial power engineering. A better solution is to take energy from the surroundings unlimited in time. It is assumed that in the future EH will be a source of high-power energy by creating appropriately extensive harvester networks. The paper describes the main directions of EH research based on magnetic transducers and characterized numerous own constructions, including harvesters with magnetic processing using the Faraday effect and modal resonance, with a large increase in voltage under the influence of coil movement, with a moving core of austenitic steel and magnetostrictive core. In particular, the construction, selected characteristics, and possible areas of harvester use are described. The issue of miniaturization of the harvester's construction and modification of the magnetostrictive core was undertaken. Magnetographic field measurements were also carried out outside the harvester. In addition, harvesters using mechanical shock and a dedicated inverter as well as a low-power electronic system were presented. A method has been developed for the use of harvesters and actuators for the wireless transmission of energy and information using Smart Ultrasonic Resonant Power System (the so-called SURPS system), an autonomous system of diagnostics of environmental and operating parameters' multi-degree-of-freedom (Multi-DOF) and the so-called wireless harvesting nodes. The directions for further research have been defined at the end. Authors recommend energy-harvesting solution to go (**Figure 1**), as an indispensable development system in EH applications. This is a versatile device from Würth Elektronik demonstrating the capabilities of EH and power supplies based on various sources of energy. There are two built-in subassemblies for obtaining energy: using a thermoelectric effect and photovoltaic panel. The electronic site consists of a series of inverters dedicated to EH by linear technology and EFM32 Giant Starter Kit (Silicone Labs) equipped in addition to the microcontroller including LED display and light sensor. This harvester provides the option of changing the configuration of connecting [4–6] power sources. This solution shows a multitude of potential power options using EH, which will be described later in the work.

**34**

**1.1 Influence of smart materials on energy harvesting**

Describing smart magnetic materials and taking into account their properties, it is difficult not to undertake in their own research the issues of their application in the field of energy recovery (EH) and—as discussed further—wireless transfer of energy and information. It can even be said that the development of EH is possible thanks to the advances in science and engineering in the field of smart materials, including those stimulated by a magnetic field. From a wide group of them, materials with a giant magnetostriction (GMM) were considered to be particularly worth the attention and acceptance as an object of research in the field of EH. The GMM properties are crucial here. A typical example is Terfenol-D. Materials with gigantic magnetostriction can convert magnetic energy into mechanical and vice versa. Thanks to such properties, these materials can be used in the construction of sensors, actuators, and harvester. GMMs obtain much larger deformations (Terfenol-D up to 70 times) than traditional magnetostrictive materials, and to achieve this effect, not very high magnetic field strength H is required. There is also the opposite effect.

Relatively small deformations generate relatively high magnetic field and therefore the induced electric current (in comparison with other ferromagnets). A very important feature of these materials is the wide range of operating temperature, as well as their low inertia (small hysteresis loop field), which facilitates their use in various conditions. The Curie temperature for Terfenol-D is 653–693 K, while the working temperature can reach up to 473 K. Examples of GMM applications in the EH range include aviation, road transport, stationary mechanical structures, medicine, sports and tourism equipment, and many more. The aim of the research is mainly to increase the efficiency of converting mechanical energy into electricity, miniaturization of harvesters, and reduction of their price. Solid Terfenol-D, despite its many advantages, has several disadvantages that hinder its wider application in the field of EH. A significant drawback is, above all, the high brittleness, which is associated with low tensile strength. Another limitation is eddy currents of considerable value, which limits the effective frequency of operation of the devices to several kilohertz. An important parameter is also the price of Terfenol-D, which remains at the level of 1 \$/1 g. These disadvantages are the reason for searching for new solutions. One of them is magnetostrictive composites, which can also be used in the construction of harvester.

## **1.2 Wireless energy and information transfer through energy harvesting**

The use of harvesters increasingly requires solving the problem of unconventional energy and information transfer by solid, liquid, and gas media. Therefore, it was considered important to characterize the state of the art in this area and undertake own research. Smart materials in this case can be effectively used for wireless energy and information transfer using ultrasonic vibrations. Most often,

piezoelectric and magnetostriction transducers are used for this purpose. There are many ways of wireless power transmission (WPT) using various couplings, e.g., inductive (most popular today since the pioneering work of N. Tesla), capacitive coupling, microwaves, optical coupling, and sound waves, including ultrasound. This last opportunity has been known for over 40 years. In 1970, the first paper [7] appeared, indicating the possibility of using ultrasounds not only for medical or engineering research but also as an energy carrier in transmission through solid bodies. The ease with which ultrasound passes through the solids was then observed. In 1998, using the given idea, a special heart stimulation electrode was patented for arrhythmia [8]. The biomedical application of ultrasound for energy transmission is intensively developed. Particularly noteworthy here is, for example, work [9], which shows the way of powering, using ultrasound, an actuator placed in the human body. The idea of this type of power lies in the fact that in the receiver, the energy of ultrasonic waves and vibrations caused by them are not converted back to the electrical voltage at all, but through the arrangement of vibrating elements—they directly supply the actuator. Other interesting studies in this area are described in [10, 11].

Much attention is devoted to energy conversion efficiency using piezoelectric transducers. The most frequently cited are works [12–14]. The last of them showed efficiency at the level of 50% in the transmission of ultrasound in the air at a distance of 70–80 m. Equally spectacular achievements are the Dutch team [15, 16]. Another interesting example is the transmission of data with the help of ultrasound over the plane [17, 18]. It should be noted that very intensively developed activities are aimed at mastering the effective transfer of energy and information through thick metal barriers, mainly using piezoelectric harvester. These works, initiated in the United States by Saulnier in 2006 [19], gained interest in the navy due to the possibility of sending energy and information through the thick walls of submarines. Particularly significant results were published in the dissertation of Lawry [20] and in a dozen or so publications after its defense, e.g., [21, 22]. The last two indicate that the state of knowledge allows the use of such relays on submarines today. The continuous supply of approximately 50 W of electricity, along with 12.4 Mbps of data through 2.5-inch (over 6 cm) metal walls, is an ideal system for use in submarines that require avoiding leakage and high safety. In [23], it is also pointed out that the system can also be used in ships, unmanned vehicles, armored personnel carriers, tanks, and airplanes.

Another large American project funded by the National Aeronautics and Space Administration (NASA) is research conducted by the team of Sherrit from the Jet Propulsion Laboratory. The research, begun already in 1998, concerned the possibility of generating and reading ultrasound signals using piezoelectric actuators and generators [23]. In 2005–2008 this technique was constantly improved. In 2005, the theoretical basis for energy transmission by flexible materials of thickness over 1.5 cm [24] using piezoelectric actuators was described and then—to improve efficiency—using special graphite "patches" attached with thin layers on both sides of the wall [25]. Obtained results were promising, and it was decided to do the first trials with use of mentioned above technology in the vehicles of the NASA. The team's many years of work have been summarized in a comprehensive publication on the physical basis of ultrasonic harvesting [26] with the use of piezoelectric receivers and transmitters. Recently, a team led by Sherrit has developed a method for feeding the stepper motor through the metal wall of the vessel [27]. Thanks to the uniform power transmission, it is possible to continuously control the motor by the generated ultrasonic waves. Interestingly, this wave is not converted here to electricity and again to the mechanical energy of the engine, but the vibrating elements cause the motor to move directly by picking up ultrasonic waves. A broader literature analysis in the field of power transfer using ultrasound was carried out in [28].

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*Energy Harvester Based on Magnetomechanical Effect as a Power Source for Multi-node Wireless…*

**2. Review of EH methods capable of supplying wireless harvesting nodes**

The development of the physics of cross-field phenomena, in which one field (e.g., mechanical, thermal, magnetic) enables energy to be obtained in a different form (e.g., electricity), progresses very quickly and is supported by achievements in the field of material engineering. This results in the fact that there are an increasing number of materials usually called smart, which can be effectively used to build

The number of physical phenomena that produce electric current is significant,

EH can also be realized using double cross fields, for example, first heat and then electric current. The interdisciplinary nature of the issue, which is energy harvesting (physics of cross effects, material engineering, mechanics, electronics), stimulates the development of science and the economy. It should be emphasized that, despite numerous works undertaken mainly in the last decade in the research centers of the most developed countries, the subject of EH and the various smart materials used for this purpose is still very topical in terms of science and application. Leading economies and research centers allocate significant resources to basic

Due to scientific goals and interests, further work was focused on the use of methods increasing the parameters of harvester, mainly energy conversion efficiency, using the acquired experience in the field of magnetomechanical cross effects, smart materials, strength of materials and mechanical structures, and measurement methods. The extent of the subject matter required the imposition of restrictions. Therefore, magnetostrictive harvesters using GMM-type materials were recognized as key. Thanks to their application, instruments that were able to recover energy from sources not yet explored such as mechanical impact were obtained. An important limitation of the magnetic core harvester is its size and weight. Installing piezoelectric harvesters is a lot simpler than a magnetic core harvester that requires a complicated mechanical construction, premagnetization,

Currently, there is a trend to create autonomous power supply systems for low-power consumer electronic devices (including the so-called toward zero-power information and communication technology (ICT)) or a variety of sensor systems and monitoring systems (e.g., structural health monitoring (SHM)), e.g., [6]. It is assumed that even the use of batteries in these cases is not an optimal solution, e.g.,

due to the troublesome replacement of batteries and their recycling.

*DOI: http://dx.doi.org/10.5772/intechopen.85987*

e.g., [29–32]. You can include here:

• Reverse magnetostriction (Villari effect)

• Thermoelectric effect (Seebeck effect)

• Differences in superconductor parameters

• Ionization using an electromagnetic field

and applied research in the field of EH.

• Faraday electromagnetic induction phenomenon

• Piezoelectric effect

• Static electricity

• Pyroelectric effect

harvester.

*Energy Harvester Based on Magnetomechanical Effect as a Power Source for Multi-node Wireless… DOI: http://dx.doi.org/10.5772/intechopen.85987*
