Author
Nima Tolou
Bio: Nima Tolou is an academic researcher from Delft University of Technology. The author has contributed to research in topics: Compliant mechanism & Stiffness. The author has an hindex of 14, co-authored 60 publications receiving 872 citations.
Papers
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TL;DR: In this paper, an alternative for harvesting low-frequency broadband vibrations, with energy harvesters with two stable configurations, is discussed, and the challenges related to nonlinear dynamics are briefly discussed.
Abstract: Powering electronics without depending on batteries is an open research field. Mechanical vibrations prove to be a reliable energy source, but low-frequency broadband vibrations cannot be harvested effectively using linear oscillators. This article discusses an alternative for harvesting such vibrations, with energy harvesters with two stable configurations. The challenges related to nonlinear dynamics are briefly discussed. Different existing designs of bistable energy harvesters are presented and classified, according to their feasibility for miniaturization. A general dynamic model for those designs is described. Finally, an extensive discussion on quantitative measures of evaluating the effectiveness of energy harvesters is accomplished, resulting in the proposition of a new dimensionless metric suited for a broadband analysis.
358 citations
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91 citations
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01 Jan 2010TL;DR: In this article, a static balanced compliant micro mechanism (SB-CMM) is proposed to compensate the positive stiffness of these mechanisms by including a static balancing mechanism (SBM), resulting in a statically balanced compliant CMM with a finite zero stiffness range at the start or a further predefined position of the overall mechanism travel range.
Abstract: Compliant mechanisms play an important role in micro mechanical structures for MEMS applications. However, the positive stiffness of these mechanisms remains a significant drawback. This stiffness can be compensated by including a static balancing mechanism (SBM), resulting in a statically balanced compliant micro mechanism (SB-CMM). This paper presents concepts and simulation results of such mechanisms, which could be applied to MEMS (SB-MEMS). Two categories of SB-CMMs are presented for different situations: the balancing force and travel path are either (1) perpendicular to each other, or (2) parallel to each other. The presented concepts provide compliant mechanisms with a finite zero stiffness range at the start or at a further predefined position of the overall mechanism travel range, respectively. The simulation results confirm the validity and performance of the presented concepts, which have been optimized for further evaluation. Incorporation of these concepts can ultimately result in a reliable, smaller, and energy efficient microsystem, having a larger useful travel range.Copyright © 2010 by ASME
50 citations
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47 citations
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01 Apr 2013-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this article, a compliant structure is proposed to deal with problems like backlash, friction and lubrication for performing ultra-precise positioning in a vacuum environment, where all six degrees of freedom are statically balanced to neutralize the gravity force and cancel out the stiffness due to compliant design of the structure.
Abstract: This paper presents a low stiffness six degrees of freedom (DoF) compliant precision stage. To deal with problems like backlash, friction and lubrication for performing ultra-precise positioning in a vacuum environment, a novel compliant structure is proposed. All six degrees of freedom are statically balanced (i.e. near zero stiffness) to neutralize the gravity force and cancel out the stiffness due to the compliant design of the structure. Cooperative action of post-buckling behaviour of bi-stable beams and constant stiffness of v-shaped beams, arranged in three units in a triangular configuration, are proposed for out-of-the-horizontal-plane motions. The in-plane motions are achieved by three flexible rods loaded near their buckling load. An investigation on adjusting the design parameters to minimize the residual actuation force is also performed. A demonstrator was manufactured and finite element modelling was performed to evaluate the concept. Experimental evaluation of the demonstrator showed that a gravity force of 34.4 N was balanced with a residual stiffness of 1.75 N/mm in a domain of 2 mm for the out-of-plane translation, while the out-of-plane rotational stiffness was less than 18.5 Nm/rad, caused by parasitic torsion of the bi-stable beams and v-shaped beams. The stiffness for in-plane translations and rotation was 0.4 N/mm and 2 Nm/rad, respectively. The novel mechanism or the principle may be applied in precision engineering or in other relevant fields, such as vibration isolation.
32 citations
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TL;DR: A review of the major efforts and findings documented in the literature can be found in this article, where a common analytical framework for bistable electromechanical dynamics is presented, the principal results are provided, the wide variety of bistably energy harvesters are described, and some remaining challenges and proposed solutions are summarized.
Abstract: The investigation of the conversion of vibrational energy into electrical power has become a major field of research. In recent years, bistable energy harvesting devices have attracted significant attention due to some of their unique features. Through a snap-through action, bistable systems transition from one stable state to the other, which could cause large amplitude motion and dramatically increase power generation. Due to their nonlinear characteristics, such devices may be effective across a broad-frequency bandwidth. Consequently, a rapid engagement of research has been undertaken to understand bistable electromechanical dynamics and to utilize the insight for the development of improved designs. This paper reviews, consolidates, and reports on the major efforts and findings documented in the literature. A common analytical framework for bistable electromechanical dynamics is presented, the principal results are provided, the wide variety of bistable energy harvesters are described, and some remaining challenges and proposed solutions are summarized.
1,158 citations
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TL;DR: A detailed overview of the energy harvesting technologies associated with piezoelectric materials along with the closely related sub-classes of pyroelectrics and ferro-electrics can be found in this article.
Abstract: This review provides a detailed overview of the energy harvesting technologies associated with piezoelectric materials along with the closely related sub-classes of pyroelectrics and ferroelectrics. These properties are, in many cases, present in the same material, providing the intriguing prospect of a material that can harvest energy from multiple sources including vibration, thermal fluctuations and light. Piezoelectric materials are initially discussed in the context of harvesting mechanical energy from vibrations using inertial energy harvesting, which relies on the resistance of a mass to acceleration, and kinematic energy harvesting which directly couples the energy harvester to the relative movement of different parts of a source. Issues related to mode of operation, loss mechanisms and using non-linearity to enhance the operating frequency range are described along with the potential materials that could be employed for harvesting vibrations at elevated temperatures. In addition to inorganic piezoelectric materials, compliant piezoelectric materials are also discussed. Piezoelectric energy harvesting devices are complex multi-physics systems requiring advanced methodologies to maximise their performance. The research effort to develop optimisation methods for complex piezoelectric energy harvesters is then reviewed. The use of ferroelectric or multi-ferroic materials to convert light into chemical or electrical energy is then described in applications where the internal electric field can prevent electron–hole recombination or enhance chemical reactions at the ferroelectric surface. Finally, pyroelectric harvesting generates power from temperature fluctuations and this review covers the modes of pyroelectric harvesting such as simple resistive loading and Olsen cycles. Nano-scale pyroelectric systems and novel micro-electro-mechanical-systems designed to increase the operating frequency are discussed.
882 citations
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TL;DR: A comprehensive review of piezoelectric energy-harvesting techniques developed in the last decade is presented, identifying four promising applications: shoes, pacemakers, tire pressure monitoring systems, and bridge and building monitoring.
720 citations
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TL;DR: A comprehensive review on the state-of-the-art of piezoelectric energy harvesting is presented, including basic fundamentals and configurations, materials and fabrication, performance enhancement mechanisms, applications, and future outlooks.
Abstract: The last decade has witnessed significant advances in energy harvesting technologies as a possible alternative to provide a continuous power supply for small, low-power devices in applications, such as wireless sensing, data transmission, actuation, and medical implants. Piezoelectric energy harvesting (PEH) has been a salient topic in the literature and has attracted widespread attention from researchers due to its advantages of simple architecture, high power density, and good scalability. This paper presents a comprehensive review on the state-of-the-art of piezoelectric energy harvesting. Various key aspects to improve the overall performance of a PEH device are discussed, including basic fundamentals and configurations, materials and fabrication, performance enhancement mechanisms, applications, and future outlooks.
513 citations
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TL;DR: In this article, a broadband piezoelectric based vibration energy harvester with a triple-well potential induced by a magnetic field was proposed and the parameters of the linear energy harvesting system without magnetic force actuation were obtained through intelligent optimization of the minimum error between numerical simulations and experimental responses.
483 citations