Movers and Shakers: Kinetic Energy Harvesting for the Internet of Things

Numerous energy harvesting wireless devices that will serve as building blocks for the Internet of Things (IoT) are currently under development. However, there is still only limited understanding of the properties of various energy sources and their impact on energy harvesting adaptive algorithms. Hence, we focus on characterizing the kinetic (motion) energy that can be harvested by a wireless node with an IoT form factor and on developing energy allocation algorithms for such nodes. In this paper, we describe methods for estimating harvested energy from acceleration traces. To characterize the energy availability associated with specific human activities (e.g., relaxing, walking, cycling), we analyze a motion dataset with over 40 participants. Based on acceleration measurements that we collected for over 200 hours, we study energy generation processes associated with day-long human routines. We also briefly summarize our experiments with moving objects. We develop energy allocation algorithms that take into account practical IoT node design considerations, and evaluate the algorithms using the collected measurements. Our observations provide insights into the design of motion energy harvesters, IoT nodes, and energy harvesting adaptive algorithms.Comment: 15 pages, 11 figure

Development of piezoelectric harvesters with integrated trimming devices

Piezoelectric cantilever harvesters have a large power output at their natural frequency, but in some applications the frequency of ambient vibrations is different fromthe harvester\u2019s frequency and/or ambient vibrations are periodicwith some harmonic components. To copewith these operating conditions harvesters with integrated trimming devices (ITDs) are proposed. Some prototypes are developed with the aid of an analytical model and tested with an impulsive method. Results show that a small trimming device can lower the main resonance frequency of a piezoelectric harvester of the same extent as a larger tip mass and, moreover, it generates at high frequency a second resonance peak. A multi-physics numerical finite element (FE) model is developed for predicting the generated power and for performing a stress-strain analysis of harvesters with ITDs. The numerical model is validated on the basis of the experimental results. Several configurations of ITDs are conceived and studied. Numerical results show that the harvesters with ITDs are able to generate relevant power at two frequencies, owing to the particular shape of the modes of vibration. The stress in the harvesters with ITDs is smaller than the stress in the harvester with a tip mass trimmed to the same frequency

A Review of Smart Materials in Tactile Actuators for Information Delivery

As the largest organ in the human body, the skin provides the important sensory channel for humans to receive external stimulations based on touch. By the information perceived through touch, people can feel and guess the properties of objects, like weight, temperature, textures, and motion, etc. In fact, those properties are nerve stimuli to our brain received by different kinds of receptors in the skin. Mechanical, electrical, and thermal stimuli can stimulate these receptors and cause different information to be conveyed through the nerves. Technologies for actuators to provide mechanical, electrical or thermal stimuli have been developed. These include static or vibrational actuation, electrostatic stimulation, focused ultrasound, and more. Smart materials, such as piezoelectric materials, carbon nanotubes, and shape memory alloys, play important roles in providing actuation for tactile sensation. This paper aims to review the background biological knowledge of human tactile sensing, to give an understanding of how we sense and interact with the world through the sense of touch, as well as the conventional and state-of-the-art technologies of tactile actuators for tactile feedback delivery

SUSTAINABLE ENERGY HARVESTING TECHNOLOGIES – PAST, PRESENT AND FUTURE

Chapter 8: Energy Harvesting Technologies: Thick-Film Piezoelectric Microgenerato

Study of the effects of magneto-mechanical coupling in the performance of electromagnetic vibration energy harvesters

Els recol·lectors electromagnètics d’energia de vibracions converteixen energia mecànica, en forma de vibracions, a electricitat. Són per tant, dispositius amb un gran potencial però també amb grans desavantatges pel que fa a adaptabilitat, eficiència i cost. El seu comportament és complex de caracteritzar, especialment quan hi ha una interacció magnètica significativa entre el propi dispositiu i components magnètics o electromagnètics externs, fet que podria derivar en un comportament no-lineal i afectar considerablement al seu rendiment. L’objectiu principal d’aquest projecte és el d’entendre millor la influencia d’aquestes forces magnètiques al rendiment mecànic d’aquest tipus de dispositius desenvolupant una eina de simulació que permeti predir el comportament d’un recol·lector sota diferents escenaris d’interès. El model que es proposa és el d’un sistema massa-esmorteïdor-molla d’un grau de llibertat amb forces magnètiques aplicades. La resposta del sistema és calculada per a una excitació d’entrada sinusoidal i a través de dos mètodes diferents. El primer és un mètode d’integració temporal mentre que el segon, conegut com a harmonic balance method, es calcula en l’espai freqüencial. Per unir la part magnètica amb la mecànica s’empra un acoblament dèbil; calculant en primer lloc les forces magnètiques que rep el dispositiu per posteriorment introduir-les en l’equació de moviment del sistema. Diferents tests experimentals representatius dels diversos escenaris a estudiar es duen a terme per tal de validar l’eina de simulació. Tant experimentalment com numèricament, en aquells casos en que hi ha forces magnètiques aplicades, s’observa un canvi substancial en la freqüència de ressonància del sistema, és a dir, un canvi en la seva rigidesa. Aquest canvi implica una reducció en la rigidesa del sistema quan l’imant del recol·lector està subjecte a forces d’atracció i un augment quan les forces són de repulsió.Electromagnetic vibration energy harvesters convert mechanical energy, in the form of vibrations, into electricity. They are, therefore, devices with huge potential but also with major drawbacks regarding adaptability, efficiency and return of investment. Their behaviour is complex to characterize, especially when there is a significant magnetic interaction between the device and external ferromagnetic or magnetic components, which could result in strong non-linear behaviours that might affect the performance of the device. The aim of this project is to understand better the influence of these magnetic forces on the mechanical system response by developing a simulation tool which can predict the behaviour of a harvester under different scenarios of interest. The proposed model is a one-degree-of-freedom spring-damper-mass system with applied magnetic forces. Its system response is computed for a sinusoidal excitation input and through two different methods. The former being a time domain integration method and the latter known as harmonic balance method, which is performed in the frequency domain. A weak coupling between magnetic and mechanical phenomena is assumed by performing the electromagnetic simulation independently and later inputting the results in the equation of motion of the system. Several experimental tests representing the different case scenarios are carried out in order to validate the simulation tool. Both experimentally and numerically, when magnetic forces are being applied, the harvester is seen to experience a significant shift in its resonant frequency, i.e., a change in its stiffness. This shift results in a softening effect if the oscillation magnet is subjected to attraction forces and in a hardening effect if, on the contrary, it is subjected to repulsion forces

A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks

In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs

Piezoelectric power harvesting devices: An overview

This article reviews the fundamental behavior of piezoelectric for applications in sensors and energy harvesting technologies. In fact, many devices and applications are evolving day-to-day depending on smart materials technology such as, scanning probe microscope (SPM) and cigarette lighters. Today, vibration based energy harvesting via piezoelectric materials has become one of the most prominent ways to provide a limited energy for self-powered wireless sensor and low power electronics. This review provides an insight that involves mathematical modeling of constitutive equations, lumped parameter model, mechanisms of piezoelectric energy conversion, and operating principle of a piezoelectric energy harvesting system. This article also focuses on the dielectric, piezoelectric, mechanical, and pyroelectric properties of piezoelectric and pyroelectric materials open to use from single crystal such as PMN-PT through ceramics PZT and polymers such as PVDF. Recent important literature is also reviewed along with energy harvesting devices proposed for use in industrial and biomedical applications

WearETE: A scalable wearable e-textile triboelectric energy harvesting system for human motion scavenging

In this paper, we report the design, experimental validation and application of a scalable, wearable e-textile triboelectric energy harvesting (WearETE) system for scavenging energy from activities of daily living. The WearETE system features ultra-low-cost material and manufacturing methods, high accessibility, and high feasibility for powering wearable sensors and electronics. The foam and e-textile are used as the two active tribomaterials for energy harvester design with the consideration of flexibility and wearability. A calibration platform is also developed to quantify the input mechanical power and power efficiency. The performance of the WearETE system for human motion scavenging is validated and calibrated through experiments. The results show that the wearable triboelectric energy harvester can generate over 70 V output voltage which is capable of powering over 52 LEDs simultaneously with a 9 × 9 cm2 area. A larger version is able to lighten 190 LEDs during contact-separation process. The WearETE system can generate a maximum power of 4.8113 mW from hand clapping movements under the frequency of 4 Hz. The average power efficiency can be up to 24.94%. The output power harvested by the WearETE system during slow walking is 7.5248 µW. The results show the possibility of powering wearable electronics during human motion