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.

https://iopscience.iop.org/article/10.1088/0964-1726/22/2/023001/pdf

A review of the recent research on vibration energy harvesting via bistable systems

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.

/pdf/piezoelectric-and-ferroelectric-materials-and-structures-for-39myuuqvo7.pdf

Piezoelectric and ferroelectric materials and structures for energy harvesting applications

High-Performance Piezoelectric Energy Harvesters and Their Applications

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.

A comprehensive review on piezoelectric energy harvesting technology: Materials, mechanisms, and applications

Broadband tristable energy harvester: Modeling and experiment verification

A compliant constant velocity constant torque universal joint to transmit a rotary movement between two angled shafts, and/or a kinematic pair with two independent rotational degrees of freedom This compliant structure is a large deflection compliant joint and the misalignment angle can be changed through the range of from 0° to 60° The mechanism includes at least three compliant or statically balanced compliant spatial 4R (four revolute joint) linkages connected between two shafts, each system including four compliant joint axes and three rigid or compliant link members The joint axes in each system are mounted so that each axis intersects one other joint axis The compliant system is symmetrical about a plane which bisects two shaft axes perpendicularly

Compliant constant velocity constant torque universal joint

Bistable compliant mechanism, comprising a buckling beam and one or more supporting beams, wherein the buckling beam and the supporting beams are made from a monolithic substrate without joints, which mechanism shows two distinct stable equilibrium positions and wherein the mechanism can switch from one stable equilibrium position to the other when subjected to an external force, wherein the buckling beam and the supporting beams are made in a single pro-cessing step operating on the monolithic substrate by a pulsed laser source that heats the substrate and carves out cuts in the substrate that separate the buckling beam from the supporting beams, and separates the supporting beams from the remainder of the substrate, whereafter the processed substrate is left at rest to cool down to room temperature.

Bistable compliant mechanism and method to manufacture such a bistable compliant mechanism

Micro mecanisme comprenant une premiere partie, une deuxieme partie (53) ayant une position reglable par rapport a la premiere partie, et un dispositif de blocage (56) adapte pour bloquer la deuxieme partie en position par rapport a la premiere partie. Le dispositif de blocage comporte un organe d'appui elastique (63) lie a la premiere partie, un premier doigt de reglage (58a) lie a la premiere partie, un deuxieme doigt de reglage (57a) lie a la deuxieme partie et s 'etendant en sens oppose du premier doigt de reglage, et l'organe d'appui elastique (63) est adapte pour exercer un appui sur le deuxieme doigt de reglage en le bloquant par friction contre le premier doigt de reglage.

Micro mécanisme à réglage de position, mouvement horloger et pièce d'horlogerie comprenant un tel mécanisme.

1 Background Body powered hand prostheses are usually controlled by shoulder movement and consist of two main components: (1) the mechanism and (2) a cosmetic covering. Investigations show that a large portion (e.g. 35 to 56% of children) abandon body powered hand prosthetics due to the relatively high operating effort needed[1]. This is attributed to stiffness of the cosmetic covering, which acts as a stiff counteracting spring [2]. To mitigate this without changing the design of the glove or the hand prosthesis a stiffness compensation mechanism (i.e. negative stiffness) could be added. The net result is a decrease in the required control force [3]. Current solutions however tend to have deficiencies such as space uptake and friction [4]. Recent advances in compliant mechanisms show benefits compared to conventional mechanisms such as compactness, no maintenance, reduced fabrication costs, more reliability [5], and possible greater ease of sterilization. Therefore, this work aims to design a stiffness compensation mechanism for hand prostheses in a compliant configuration that benefits from stiffness adjustability, and can be used for different hand prosthesis or tuned for different users. 2 Methods Data Acquisition A survey of scapular muscle force of users has been made [6-7] in order to understand the required compensation level for hand prosthesis (required control force Otto Bock 8S6, 142x50L in combination with a WILMER WHD-4 for 4 year old child and intermittent use is 25N [3]).

Stiffness Softening in Body Powered Hand Prothesis

The invention relates to a micromechanism comprising a first part (15), a second part (53) having a position that can be adjusted in relation to the first part, and a locking device (56) for locking the second part in position in relation to the first part. The locking device comprises an elastic bearing body (63) connected to the first part, a first adjustment finger (58a) connected to the first part, and a second adjustment finger (57a) connected to the second part and extending in the opposite direction to that of the first adjustment part, and the elastic bearing body (63) is designed to exert pressure on the second adjustment finger by frictionally locking it against the first adjustment finger.

Nima Tolou

Papers

Compliant constant velocity constant torque universal joint

Bistable compliant mechanism and method to manufacture such a bistable compliant mechanism

Micro mécanisme à réglage de position, mouvement horloger et pièce d'horlogerie comprenant un tel mécanisme.

Stiffness Softening in Body Powered Hand Prothesis

Position-adjustable micromechanism, time-keeping movement and timepiece comprising such a mechanism