MEMS structures utilizing the piezoelectric effect are used to fabricate a wide variation of sensingand actuating devices. The most common piezoelectric material for MEMS is PZT which has beenintensively investigated. In order to improve the performance of PZT and create materialsoptimized for specific applications, altered versions of PZT are being investigated. One way toalter the behavior of PZT is to introduce dopants. In this work, doped and non-doped PZT filmshave been fabricated using the sol-gel deposition process and the transverse piezoelectriccoefficient (e31) value of these films has been measured. Two types of dopants have been used tosee if these dopants could boost the e31 making the film more suitable for energy harvestingapplications. Furthermore processes alteration has been performed to increase the quality andthroughput of the PZT film fabricated at Silex Microsystems. The quality of the film could be seenby inspecting the level of non-uniform areas in regards to color and clarity of the film. The qualitywas improved and the color and clarity uniformity across the wafer was visibly improved. Thethroughput of the PZT deposition process was increased by ~33% by finding an alternative processrequiring fewer crystallization steps. One type of dopant gives an e31 increase of ~12% compared to the highest e31 value previously obtained at Silex Microsystems using non-doped PZT. / Piezoelektrisk MEMS används för att konstruera många olika sorters av sensorer och aktuatorer.Det piezoelektriska material som används mest frekvent inom MEMS är PZT, vilket har blivitintensivt undersökt. För att förbättra prestandan hos PZT och skapa material optimerade förspecifika applikationer, undersöks olika modifikationer av PZT. Ett sätt att modifiera egenskapernahos PZT är att introducera dopningsämnen. I detta arbete har filmer av dopad och odopad PZTtillverkats med en sol-gelprocess och e31-värdet hos dessa filmer har mätts. Två typer avdopningsämnen har använts för att se om ett högre e31-värde kunde nås vilket skulle göra filmenbättre för ”energy harvesting” tillämpningar. Dessutom har process-modifikationer gjorts för attförbättra sol-gel processen hos Silex Microsystems. Modifikationerna gjordes med målet attförbättra kvaliteten hos filmen och minska processtiden. Kvaliteten hos filmen kunde observerasgenom att se i vilken utsträckning filmen var uniform i färg och klarhet. Efter modifikationerna påprocessen så förbättrades både dessa aspekter. Färgskillnader kunde inte längre observeras påfilmen och klarheten ökade. Produktionstiden minskade med ~33% med hjälp av en stabilalternativ process som krävde färre kristalliseringssteg. Ett av dopningsämnena förbättrade e31-värdet med ~12% jämfört med det e31-värdet hos den odopade filmen tidigare skapad av SilexMicrosystems.

Point absorber style marine energy harvesters have been investigated based on their structure, energy harvesting efficiency, and reliability along with costs. However, due to the continuously varying ocean conditions and climates, the system usually suffers low power output and reliability from low input and high Peak to Average Ratio (PAR). Therefore, a Mechanical Motion Rectifier (MMR) based point absorber is introduced in this thesis to promote the harvesting efficiency and reduce the PAR by unifying the input rotation, and allow disengagement inside the gearbox during low power output phase. A 1:20 scale full system was then designed, prototyped, and tested based on the MMR. The bench test results show that the proposed MMR based point absorber could improve the energy conversion efficiency by 10 percent, which brings feasibility to the implementation. Traditional Wave Energy Converter(WEC) can only harvest ocean waves while ocean current is also one of the significant energy sources widely existing in ocean. In order to further increase the energy harvesting efficiency, one individual energy input source shows its limits. A vast majority of places around the world tends to co-exist both marine waves and current, and extracting energy from both sources could potentially increase the electric power output. Therefore, the Hybrid Wave and Current Energy Harvester (HWCEC) is introduced along with the hybrid gearbox. It is capable of harvesting energy from both ocean waves and current simultaneously so that the electric power output is significantly higher from a combined system. Tank test data shows 38-79 percent of electric power output promotion of an HWCEC compared to a regular WEC, and 70 percent reduced PAR in irregular wave condition. After that, system electric damping has been thoroughly investigated on both electrical side and mechanical side. The best power output corresponding electrical resistance is identical to the generator internal resistance while the best gear ratio of 3.5 is determined via both simulation and tank test. Furthermore, the system's PAR has been investigated by analyzing the trend of the peak occurrence. Tank test data shows the HWCEC's output power peak occurrence is at roughly 20 percent located at its PAR average. Therefore, the HWCEC system can promote energy harvesting efficiency to the combined system design, and improve its reliability from a significantly reduced peak to average ratio. It also gives HWCEC a large variety of deployable locations compared to a regular WEC under more marine environment. Furthermore, a new design of the Hybrid model, Hybrid LITE, is then developed, which not only features the HWCEC features, but also a lightweight, immersive and inflatable design for fast deployment and transportation. Since the system is built with an open water chassis, the overall system robustness is significantly improved since no water sealing is required on the powertrain compared to the HWCEC. / Master of Science / Ocean contains enormous amount of Marine Hydrokinetic (MHK) energy including ocean waves, tidal streams, and ocean current. Marine energy was investigated due to its continuous, massive and high-density hydrokinetic power output. In order to better serve the needs for ocean surface applications and take advantage of high energy density compared to other renewable energy sources, Wave Energy Converters (WEC) has been investigated, which harvests energy from the ocean wave. In the past years of study, it came to our attention that places such as the west coast of the U.S., northern Europe, and the Mediterranean area tend to have both abundant marine wave and current energy. Therefore, a new design of the Hybrid Wave and Current Energy Converter (HWCEC) is investigated for higher power output. In order to combine the energy sources from waves and current, a Hybrid Gearbox was selected to joint the power and unifies the motion from the wave for a higher efficiency. Simulations and 1:10 ratio co-existing wave and current basin test have been conducted for the HWCEC. By using the same system, single wave or current input are used as the baselines and the dual input HWCEC has demonstrated great benefit and potential. The electric damping and the gearbox ratio of the HWCEC are studied for the best power output in both simulation and tank test. The result shows that the HWCEC could promote up to 38-71 percent of electricity output in a regular wave condition, and 79 percent in irregular wave condition. The Peak to Average Ratio (PAR) is a key factor for system's mechanical reliability. The testing shows that the HWCEC can reduce 70 percent of the peak motion and contribute to the average, which is an indirect indicator of the system's better reliability. Furthermore, to align the needs of the design for real-life applications, The Hybrid LITE Converter idea was then developed for special deployment requirements for the future application of the Hybrid system. It has a novel open-system design with the implementation of a newly designed hybrid gearbox. This converter has the potential of promoting the reliability, deployability and weight reduction for easy transportation from its open system design compared to HWCEC. The system modeling could be done as future work varies from the changing deployment locations for higher electric power output.

Wearable and mobile devices are an important part of our daily life. Most of those devices are powered by batteries. The limited life span of batteries constitutes a limitation, especially in a multiple-day expedition, where electrical power can not access conveniently. At the same time, there is a huge amount of energy stored in the human body. While walking, there is a large amount of power dissipated in the human body as negative muscle work and the energy loss by impact. By sourcing locally and using locally, human body energy harvesting is a promising solution. This dissertation focuses on harvesting energy from the human body to power wearable and mobile devices while poses a minimum burden on the human body. Three topics related to the human body energy harvesting are explored, i.e, energy harvesting backpack, negative muscle work harvester, and energy harvesting tile/paver. The energy harvesting backpack was invented in 2006. Extensive work was done to improve the performance of backpack energy harvester. The backpack is modeled as a spring-mass-damper system. Mechanical Motion Rectifier was added to the spring-mass-damper system to increase the frequency bandwidth. A spring is added to the spring-mass-damper system, between the harvester and the backpack mass, and a inerter-based 2DOF (degree-of-freedom) backpack is created. The inerter-based 2DOF backpack improves the power output, frequency bandwidth, and power stroke ratio performance. MMR was added to the inerter-based 2DOF backpack to reduce the peak stroke. Compared with the conventional spring-mass-damper backpack, the MMR and inerter-based 2DOF backpack can harvest more power with large bandwidth at a small sacrifice of stroke. The electric damping was also tuned to increase the power output and bandwidth for the energy harvesting backpack. The negative work harvester mounts on the human ankle and harvests energy in the terminal stance phase in human walking, when the calf muscle is doing negative muscle work. This harvester is an analogy to regenerative brake in vehicles. The energy harvesting paver/tile harvests energy when the heel contacts with ground and energy are dissipated by impact. / Doctor of Philosophy / Wearable and mobile devices are an important part of our daily life. Most of those devices are powered by batteries. The limited life span of batteries constitutes a limitation, especially in a multiple-day expedition, where electrical power can not access conveniently. At the same time, there is a huge amount of energy stored in the human body. While walking, there is a large amount of power dissipated in the human body as negative muscle work and the energy loss by impact. By sourcing locally and using locally, human body energy harvesting is a promising solution. This dissertation focuses on harvesting energy from the human body to power wearable and mobile devices while poses a minimum burden on the human body. Three topics related to the human body energy harvesting are explored, i.e, energy harvesting backpack, negative muscle work harvester, and energy harvesting tile/paver. The energy harvesting backpack was invented in 2006. Extensive work was done to improve the performance of backpack energy harvester. The backpack is modeled as a spring-mass-damper system. Extensive work have been done to make the energy harvesting backpack broad frequency bandwidth. The negative work harvester mounts on the human ankle and harvests energy in the terminal stance phase in human walking. This harvester is an analogy to regenerative brake in vehicles. The energy harvesting paver/tile harvests energy when the heel contacts with ground and energy are dissipated by impact.

In der vorliegenden Arbeit wird die Entwicklung eines kinetischen Energy Harvesters vorgestellt, der auf Grundlage des elektrostatischen Wandlerprinzips aus Vibrationen elektrische Energie generiert. Für die Umsetzung wurde eine Siliziummikrostruktur entworfen, die für Arbeitsfrequenzen unter 100 Hz ausgelegt ist. Die Zahnstruktur der verwendeten Elektroden ermöglicht Spaltabstände im Submikrometerbereich und folglich große Kapazitätsänderungen, die durch die Elektrodengeometrie zusätzlich mit einer höheren Frequenz als die mechanische Bewegung stattfinden. Vergleichsweise große Leistungsausbeuten und geringe Quellimpedanzen sind dadurch erreichbar. Die geometrischen Parameter der Elektroden wurden unter Berücksichtigung der auftretenden Fertigungstoleranzen und Wechselwirkungen zueinander optimiert. Für die Ausnutzung einer ausreichend großen Inertialmasse wurde ein feinwerktechnisch hergestellter Hebelmechanismus an die Mikrostruktur angekoppelt. Über diesen wird zusätzlich ein neuer Ansatz zur Abstimmung der Eigenfrequenz des Harvesters umgesetzt. Experimentelle Untersuchungen zeigten Ausgangsleistungen im einstelligen Mikrowattbereich bei Anregungen im Zehntel m/s²-Bereich. Durch fortschreitende Optimierungen der Fertigungstechnologie sind noch deutliche Leistungssteigerungen um mindestens zwei Größenordnungen möglich. Weiterhin wird ein Energiemanagementsystem vorgestellt, welches die effiziente Übertragung der Energie auf den Verbraucher ermöglicht. / In this work the development of a kinetic energy harvester using the electrostatic conversion principle is presented. The silicon microstructure is designed to work in frequency ranges below 100Hz. Its toothed electrode structure enables gap distances in the sub micrometer range and consequently high changes of capacitance. Additionally, due to the electrode geometry the frequency of the capacitance changes is higher then the frequency of the mechanical movement. Thus high power outputs and low source impedances can be reached. The electrodes geometric parameters were optimized considering manufacturing tolerances and interactions of the parameters. To reach a sufficient inertial mass, a lever mechanism manufactured by precision engineering was connected to the microstructure. This mechanism also allows the implementation of a new method of frequency tuning. In experimental tests power outputs in the single digit microwatt range under excitations of 0.3 m/s² were reached. In accordance of further optimizations of the manufacturing technology significantly higher outputs, by at least two orders of magnitude, are possible,. Furthermore an energy management system is presented, that allows the efficient transfer of the electrical energy to the consumer.

In der vorliegenden Arbeit wird die Entwicklung eines kinetischen Energy Harvesters vorgestellt, der auf Grundlage des elektrostatischen Wandlerprinzips aus Vibrationen elektrische Energie generiert. Für die Umsetzung wurde eine Siliziummikrostruktur entworfen, die für Arbeitsfrequenzen unter 100 Hz ausgelegt ist. Die Zahnstruktur der verwendeten Elektroden ermöglicht Spaltabstände im Submikrometerbereich und folglich große Kapazitätsänderungen, die durch die Elektrodengeometrie zusätzlich mit einer höheren Frequenz als die mechanische Bewegung stattfinden. Vergleichsweise große Leistungsausbeuten und geringe Quellimpedanzen sind dadurch erreichbar. Die geometrischen Parameter der Elektroden wurden unter Berücksichtigung der auftretenden Fertigungstoleranzen und Wechselwirkungen zueinander optimiert. Für die Ausnutzung einer ausreichend großen Inertialmasse wurde ein feinwerktechnisch hergestellter Hebelmechanismus an die Mikrostruktur angekoppelt. Über diesen wird zusätzlich ein neuer Ansatz zur Abstimmung der Eigenfrequenz des Harvesters umgesetzt. Experimentelle Untersuchungen zeigten Ausgangsleistungen im einstelligen Mikrowattbereich bei Anregungen im Zehntel m/s²-Bereich. Durch fortschreitende Optimierungen der Fertigungstechnologie sind noch deutliche Leistungssteigerungen um mindestens zwei Größenordnungen möglich. Weiterhin wird ein Energiemanagementsystem vorgestellt, welches die effiziente Übertragung der Energie auf den Verbraucher ermöglicht. / In this work the development of a kinetic energy harvester using the electrostatic conversion principle is presented. The silicon microstructure is designed to work in frequency ranges below 100Hz. Its toothed electrode structure enables gap distances in the sub micrometer range and consequently high changes of capacitance. Additionally, due to the electrode geometry the frequency of the capacitance changes is higher then the frequency of the mechanical movement. Thus high power outputs and low source impedances can be reached. The electrodes geometric parameters were optimized considering manufacturing tolerances and interactions of the parameters. To reach a sufficient inertial mass, a lever mechanism manufactured by precision engineering was connected to the microstructure. This mechanism also allows the implementation of a new method of frequency tuning. In experimental tests power outputs in the single digit microwatt range under excitations of 0.3 m/s² were reached. In accordance of further optimizations of the manufacturing technology significantly higher outputs, by at least two orders of magnitude, are possible,. Furthermore an energy management system is presented, that allows the efficient transfer of the electrical energy to the consumer.

Energy harvesting is playing an increasingly important role in supplying power to monitoring and automation systems such as structural health monitoring using wireless sensor networks. This importance is most notable when the structures to be monitored are in rural, hazardous, or limited access environments such as busy highway bridges where traffic would be greatly disrupted during maintenance, inspection, or battery replacement. This thesis provides an overview of energy harvesting technologies and details the design, prototyping, testing, and simulation of an energy harvester which converts the vibrations of steel highway bridges into stored electrical energy through the use of a translational electromagnetic generator, to power a wireless sensor network for bridge structural health monitoring. An analysis of bridge vibrations, the use of nonlinear and linear harvester compliance, resonant frequency tuning, and bandwidth widening to maximize the energy harvested is presented. The design approach follows broad and focused background research, functional analysis, broad and focused concept generation and selection, early prototyping, parametric modeling and simulation, rapid prototyping with selective laser sintering, and laboratory testing with replicated bridge vibration. The key outcomes of the work are: a breadth of conceptual designs, extensive literature review, a prototype which harvests an average of 80µW under bridge vibration, a prototype which provides quick assembly, mounting and tuning, and the conclusion that a linear harvester out performs a nonlinear harvester with stiffening magnetic compliance for aperiodic vibrations such as those from highway bridges. / text

This paper summarizes and extends the modeling state of the art of magnetostrictive energy harvesters with a focus on the pick-up coil design. The harvester is a one-sided clamped galfenol unimorph loaded with two brass pieces each containing a permanent magnet to create a biased magnetic field. Measurements on different pick-up coils were conducted and compared with results from an analytic model. Resistance, mass and inductance were formulated and proved by measurements. Both the length for a constant number of turns and the number of turns for a constant coil length were also modeled and varied. The results confirm that the output voltage depends on the coil length for a constant number of turns and is higher for smaller coils. In contrast to a uniform magnetic field, the maximal output voltage is gained if the coil is placed not directly at but near the fixation. Two effects explain this behavior: Due to the permanent magnet next to the fixation, the magnetic force is higher and orientates the magnetic domains stronger. The clamping locally increases the stress and forces the magnetic domains to orientate, too. For that reason the material is stiffer and therefore the strain smaller. The tradeoff between a higher induced voltage in the coil and an increasing inductance and resistance for every additional turn are presented together with an experimental validation of the models. Based on the results guidelines are given to design an optimal coil which maximizes the output power for a given unimorph.

Among various energy harvesting technologies reverse electrowetting-on-dielectric energy harvesting (REWOD) has been proved to harvest energy from low frequency motion such as many human motion activities (e.g. walking, running, jogging etc.). Voltage rectification and DC-DC boosting of low magnitude AC voltage from REWOD can be used to reliably self-power the wearable sensors. In this work, a commercial component-based rectifier and DC-DC converter is designed and experimentally verified, for further miniaturization standard 180 nm CMOS process is used to design the rectifier and the DC-DC boost converter.This work also includes the MATLAB based model for REWOD energy harvester for various REWOD models. In REWOD energy harvesting, a mechanical input during the motion causes the electrolyte placed in between two dissimilar electrodes to squeeze back and forth thereby periodically changing the effective interfacial area, hence generating alternating current. The alternating current is given to the rectifier design. There is no realistic model that has been developed yet for this technique. Thereby, a MATLAB based REWOD model is developed for the realistic simulation of the REWOD phenomenon. In the work, a comparison of different REWOD models such as planar surface, rough surface and porous models are performed demonstrating the variations in capacitance, current and voltage.

La récupération de l'énergie des vibrations est un concept relativement nouveau qui peut être utilisé dans l'alimentation des dispositifs embarqués de puissance à micro-échelle avec l'énergie des vibrations omniprésentes dans l’environnement. Cette thèse contribue à une étude générale des récupérateurs de l'énergie des vibrations (REV) employant des transducteurs électrostatiques. Un REV électrostatique typique se compose d'un transducteur capacitif, de l'électronique de conditionnement et d’un élément de stockage. Ce travail se concentre sur l'examen du circuit de conditionnement auto-synchrone proposé en 2006 par le MIT, qui combine la pompe de charge à base de diodes et le convertisseur DC-DC inductif de type de flyback qui est entraîné par le commutateur. Cette architecture est très prometteuse car elle élimine la commande de grille précise des transistors utilisés dans les architectures synchrones, tandis qu'un commutateur unique se met en marche rarement. Cette thèse propose une analyse théorique du circuit de conditionnement. Nous avons développé un algorithme qui par commutation appropriée de flyback implémente la stratégie de conversion d'énergie optimale en tenant compte des pertes liées à la commutation. En ajoutant une fonction de calibration, le système devient adaptatif pour les fluctuations de l'environnement. Cette étude a été validée par la modélisation comportementale.Une autre contribution consiste en la réalisation de l'algorithme proposé au niveau du circuit CMOS. Les difficultés majeures de conception étaient liées à l'exigence de haute tension et à la priorité de la conception faible puissance. Nous avons conçu un contrôleur du commutateur haute tension de faible puissance en utilisant la technologie AMS035HV. Sa consommation varie entre quelques centaines de nanowatts et quelques microwatts, en fonction de nombreux facteurs - paramètres de vibrations externes, niveaux de tension de la pompe de charge, la fréquence de la commutation de commutateur, la fréquence de la fonction de calibration, etc.Nous avons également réalisé en silicium, fabriqué et testé un commutateur à haute tension avec une nouvelle architecture de l'élévateur de tension de faible puissance. En montant sur des composants discrets de la pompe de charge et du circuit de retour et en utilisant l'interrupteur conçu, nous avons caractérisé le fonctionnement large bande haute-tension du prototype de transducteur MEMS fabriqué à côté de cette thèse à l'ESIEE Paris. Lorsque le capteur est excité par des vibrations stochastiques ayant un niveau d'accélération de 0,8 g rms distribué dans la bande 110-170 Hz, jusqu'à 0,75 µW de la puissance nette a été récupérée. / Vibration energy harvesting is a relatively new concept that can be used in powering micro-scale power embedded devices with the energy of vibrations omnipresent in the surrounding. This thesis contributes to a general study of vibration energy harvesters (VEHs) employing electrostatic transducers. A typical electrostatic VEH consists of a capacitive transducer, conditioning electronics and a storage element. This work is focused on investigations of the reported by MIT in 2006 auto-synchronous conditioning circuit, which combines the diode-based charge pump and the inductive flyback energy return driven by the switch. This architecture is very promising since it eliminates precise gate control of transistors employed in synchronous architectures, while a unique switch turns on rarely. This thesis addresses the theoretical analysis of the conditioning circuit. We developed an algorithm that by proper switching of the flyback allows the optimal energy conversion strategy taking into account the losses associated with the switching. By adding the calibration function, the system became adaptive to the fluctuations in the environment. This study was validated by the behavioral modeling. Another contribution consists in realization of the proposed algorithm on the circuit level. The major design difficulties were related to the high-voltage requirement and the low-power design priority. We designed a high-voltage analog controller of the switch using AMS035HV technology. Its power consumption varies between several hundred nanowatts and a few microwatts, depending on numerous factors - parameters of external vibrations, voltage levels of the charge pump, frequency of the flyback switching, frequency of calibration function, etc. We also implemented on silicon, fabricated and tested a high-voltage switch with a novel low power level-shifting driver. By mounting on discrete components the charge pump and flyback circuit and employing the proposed switch, we characterized the wideband high-voltage operation of the MEMS transducer prototype fabricated alongside this thesis in ESIEE Paris. When excited with stochastic vibrations having an acceleration level of 0.8 g rms distributed in the band 110-170 Hz, up to 0.75 $\mu$W of net electrical power has been harvested.

For many years batteries have been used as the main power sources for portable electronic devices. However, the rate of scaling in integrated circuits and micro-electro-mechanical systems (MEMS) has been much higher than that of the batteries technology. Therefore, a need to replace these temporary energy reservoirs with small sized continuously charged energy supply units has emerged. These units, named as energy harvesters, use several types of ambient energy sources such as heat, light, and vibration to provide energy to intelligent systems such as sensor nodes. Among the available types, vibration based electromagnetic (EM) energy harvesters are particularly interesting because of their simple structure and suitability for operation at low frequency values (&lt / 10 Hz), where most vibrations exits. However, since the generated EM power and voltage is relatively low at low frequencies, high performance interface electronics is required for efficiently transferring the generated power from the harvester to the load to be supplied. The aim of this study is to design low power and efficient interface electronics to convert the low voltage and low power generated signals of the EM energy harvesters to DC to be usable by a real application. The most critical part of such interface electronics is the AC/DC converter, since all the other blocks such as DC/DC converters, power managements units, etc. rely on the rectified voltage generated by this block. Due to this, several state-of-the-art rectifier structures suitable for energy harvesting applications have been studied. Most of the previously proposed rectifiers have low conversion efficiency due to the high voltage drop across the utilized diodes. In this study, two rectifier structures are proposed: one is a new passive rectifier using the Boot Strapping technique for reducing the diode turn-on voltage values / the other structure is a comparator-based ultra low power active rectifier. The proposed structures and some of the previously reported designs have been implemented in X-FAB 0.35 &micro / m standard CMOS process. The autonomous energy harvesting systems are then realized by integrating the developed ASICs and the previously proposed EM energy harvester modules developed in our research group, and these systems have been characterized under different electromechanical excitation conditions. In this thesis, five different systems utilizing different circuits and energy harvesting modules have been presented. Among these, the system utilizing the novel Boot Strap Rectifier is implemented within a volume of 21 cm3, and delivers 1.6 V, 80 &micro / A (128 &micro / W) DC power to a load at a vibration frequency of only 2 Hz and 72 mg peak acceleration. The maximum overall power density of the system operating at 2 Hz is 6.1 &micro / W/cm3, which is the highest reported value in the literature at this operation frequency. Also, the operation of a commercially available temperature sensor using the provided power of the energy harvester has been shown. Another system utilizing the comparator-based active rectifier implemented with a volume of 16 cm3, has a dual rail output and is able to drive a 1.46 V, 37 &micro / A load with a maximum power density of 6.03 &micro / W/cm3, operating at 8 Hz. Furthermore, a signal conditioning system for EM energy harvesting has also been designed and simulated in TSMC 90 nm CMOS process. The proposed ASIC includes a highly efficient AC-DC converter as well as a power processing unit which steps up and regulates the converted DC voltages using an on-chip DC/DC converter and a sub-threshold voltage regulator with an ultra low power management unit. The total power consumption on the totally passive IC is less than 5 &micro / W, which makes it suitable for next generation MEMS-based EM energy harvesters. In the frame of this study, high efficiency CMOS rectifier ICs have been designed and tested together with several vibration based EM energy harvester modules. The results show that the best efficiency and power density values have been achieved with the proposed energy harvesting systems, within the low frequency range, to the best of our knowledge. It is also shown that further improvement of the results is possible with the utilization of a more advanced CMOS technology.