An energy harvesting device combined with a giant magnetoimpedance (GMI) sensor is presented to analyze low frequency vibrating systems. An electromagnetic harvester based on magnetic levitation is proposed for the electric power generation. The device is composed of two fixed permanent magnets at both ends of a cylindrical frame, a levitating magnet acting as inertial mass and a pick-up coil to collect the induced electromotive force. At the resonance frequency (10 Hz) a maximum electrical power of 1.4 mW at 0.5 g is generated. Moreover, an amorphous wire was employed as sensor nucleus for the design of a linear accelerometer prototype. The sensor is based on the GMI effect where the impedance changes occur as a consequence of the variations of the effective magnetic field due to an oscillating magnetic element. As a result of the magnet’s periodic motion, an amplitude modulated signal (AM) was obtained, its amplitude being proportional to mechanical vibration amplitude (or acceleration). The sensor’s response was examined for a simple ferrite magnet under vibration and compared with that obtained for the vibrational energy harvester. As a result of the small amplitudes of vibration, a linear sensor response was obtained that could be employed in the design of low cost and simple accelerometers.

Pollution, the lack of energy security, and rare earth supply constraints have given rise to the research of alternatives in energy matters at all levels. In this context, ambient energy harvesting has become an important research path, aligned with the UN sustainable development goals (7- Affordable and clean energy; 9- Industry, innovation and infrastructure). Many kinds of energy harvesters exist, classified according to the energy harvested, the technology used, their size, or their application. This thesis focuses on harvesting vibration energy through electromagnetic harvesters based on magnetic levitation. The main objective is to design devices that allow for the replacement of batteries and wiring in sensor networks and portable devices. It should be noted that both the analysis and the design were carried out using Open Source tools, thus facilitating access and reproducibility for researchers and technologists interested in this field. First, a review of the state of the art was conducted, pointing out the advantages and limitations of the different types of harvesters. This analysis puts the current interest of the work into context, highlighting the improvements that can lead to innovative results in this field. Furthermore, the physical principles underlying the work have been introduced, along with the main tools (theoretical, computational, or experimental) used in its development. The first development consisted of a harvester based on a vertical one degree of freedom (1 DoF) magnetic spring, characterized by an ultra-low resonance frequency (1.7 Hz). These devices are based on the levitation of a moving magnet under the action of the magnetic field generated by a fixed magnet used as a base. For its design, an optimization algorithm based on analytical equations (Matlab scripts compatible with GNU Octave) has been implemented, whose solutions are refined and validated through finite element analysis (FEA). The use of ferrite magnets as a fixed magnet constitutes a technical and environmental improvement over conventional magnetic levitation harvesters, which are usually characterized by higher resonance frequencies and the exclusive use of rare earth magnets. However, the device presents a limitation regarding its portability due to the high weight of the fixed ferrite magnet used. Therefore, its application can be oriented towards large-scale infrastructures, such as bridges or viaducts. In the next stage, the design procedure was generalized for the optimization of the harvester in terms of weight and cost. After analyzing different ferrite magnet configurations for the fixed magnet, a harvester with a resonance frequency of 2.8 Hz and a portable size was prototyped. The use of resin guides manufactured by 3D printing for the displacement of the moving magnet yielded demonstrable improvements in manufacturing flexibility, performance, and cost reduction. As a complement to the previous studies, more complex systems were explored. On one hand, harvesters based on vertical two degrees of freedom (2 DoF) magnetic springs, integrating two magnets in levitation. The study, focused on the Dynamic analysis of the magnets’ displacement, shows the superposition of multiple resonance modes, giving rise to a broader operating bandwidth. On the other hand, regenerative shock absorbers have been analyzed, capable of operating simultaneously as dampers and generators. These larger-scale systems are designed to replace conventional shock absorbers in vehicles, as they can withstand greater forces while generating significant electrical power. Finally, the study of composite materials composed of magnetic particles embedded in a polymeric matrix is presented, with the purpose of using them as customized magnets. The study has focused on the development of calculation tools for the estimation of the generated magnetic field. Although the results indicate that their use in levitation or electrical generation is unfeasible (low magnetic field strength), their possible application in microactuators or sensors is promising. As a complement, the annexes and datasets include additional information (analytical equations of the magnetic field and forces) as well as dynamic análisis procedures for resonant systems and scripts for the Open Source 3D finite element simulation program GetDP.