In the recent years triboelectric energy harvesting has gained a lot of research attention, and numerous triboelectric harvester designs have been proposed. We introduce a novel triboelectric energy harvesting architecture, where animal hair is used as the active material with a high positive charge affinity. To induce the triboelectric effect, animal hair is then brought into contact with polytetrafluoroethylene which in turn has a high negative charge affinity. In our approach, the electrodes are built as an array of individual charge collecting pins, which protrude into and interweave with the animal hair and skin and act as the net charge collector. The generators are built with two different approaches: a) by using 3D-printed structures with miniature electrode arrays and b) by using conductive fabrics arranged in a specific laminated structure. These are then tested in the laboratory in interaction with different animal hair materials with a novel methodology based on using a robotic manipulator test bed.
Kinetic energy from vibrations emerging from mechanical systems such as machines and vehicles has been thoroughly studied as a power source in the last two decades. Numerous kinetic energy harvesters have been built to convert human locomotion into electrical power but haven’t been implemented on a wide commercial scale. On the other hand, energy harvesters for farm animals haven’t been studied as much. In this paper, we present a three-dimensional electromagnetic induction based kinetic energy harvester optimized specifically for cattle wearable applications. All the device parameters are obtained with an empirical optimization procedure by considering specific cattle locomotion characteristics. The prototype is 3-D printed with low friction and impact resistant materials. Finally, the device is tested in a real free grazing scenario with live cattle. The kinetic energy harvester performed well and was able to power the load and transmit animal body temperature data over long distances for up to 7 times/h.
The energy-harvesting efficiency of a magnetostrictive energy harvester feeding a load with a resistive input impedance is described with four non-dimensional parameters: electromagnetic-mechanical spring constant ratio, primary damping ratio, coil damping ratio, and damping ratio of input resistance. Among the parameters, the damping ratio of input resistance has an optimal value while the energy-harvesting efficiency becomes high as the electromagnetic-mechanical spring constant ratio increases or as the primary damping ratio or the coil damping ratio decreases. This paper presents experimental investigation methods to find and validate the optimal damping ratio of a magnetostrictive energy harvester under free vibration. It was found that the unimorph magnetostrictive energy harvester investigated in this study can harvest 10.1% of given mechanical energy with the optimally tuned damping ratio of input resistance.
In this paper the authors present a novel application for electromagnetic kinetic energy harvesting focusing on farm animal wearables used in precision livestock farming IoT technologies. Converting the locomotion of domesticated animals, like cow steps or cow ear movement, into electrical energy with inertial kinetic energy harvesters hasn’t been fully researched thus far. The kinetic energy converted this way could potentially be used to power smart farming wearables used for location, disease or lifecycle events detection, thus eliminating the need for finite lifetime batteries. In this work, a proof-of-concept of a cow step energy harvester is presented in detail. At first a short review of the state of the art is given which formed the basis of the research, followed by locomotion logging experiments. Finite element modelling of the kinetic energy harvester is used for parameter analysis and initial design followed by laboratory testing and available power estimation. Finally, the construction of the wearable harvester is presented together with custom wearable measuring equipment. Field experiments were performed with free grazing Finncattle at a dairy farm in Tampere, Finland, which proved that a cow step based kinetic energy harvester can be used to power a Bluetooth beacon.
There is an evident need for monitoring pollutants and/or other conditions in river flows via wireless sensor networks. In a typical wireless sensor network topography, a series of sensor nodes is to be deployed in the environment, all wirelessly connected to each other and/or their gateways. Each sensor node is composed of active electronic devices that have to be constantly powered. In general, batteries can be used for this purpose, but problems may occur when they have to be replaced. In the case of large networks, when sensor nodes can be placed in hardly accessible locations, energy harvesting can thus be a viable powering solution. The possibility to use three different small-scale river flow energy harvesting principles is hence thoroughly studied in this work: a miniaturized underwater turbine, a so-called ‘piezoelectric eel’ and a hybrid turbine solution coupled with a rigid piezoelectric beam. The first two concepts are then validated experimentally in laboratory as well as in real river conditions. The concept of the miniaturised hydro-generator is finally embedded into the actual wireless sensor node system and its functionality is confirmed.
Scavenging of low-level ambient vibrations i.e. the conversion of kinetic into electric energy, is proven as effective means of powering low consumption electronic devices such as wireless sensor nodes. Cantilever based scavengers are characterised by several advantages and thus thoroughly investigated; analytical models based on a distributed parameter approach, Euler-Bernoulli beam theory and eigenvalue analysis have thus been developed and experimentally verified. Finite element models (FEM) have also been proposed employing different modelling approaches and commercial software packages with coupled analysis capabilities. An approach of using a FEM analysis of a piezoelectric cantilever bimorph under harmonic excitation is used in this work. Modal, harmonic and linear and nonlinear transient analyses are performed. Different complex dynamic effects are observed and compared to the results obtained by using a distributed parameter model. The influence of two types of finite elements and three mesh densities is also investigated. A complex bimorph cantilever, based on commercially available Midé Technology® Volture energy scavengers, is then considered. These scavengers are characterised by an intricate multilayer structure not investigated so far in literature. An experimental set-up is developed to evaluate the behaviour of the considered class of devices. The results of the modal and the harmonic FEM analyses of the behaviour of the multilayer scavengers are verified experimentally for three different tip masses and 12 different electrical load values. A satisfying agreement between numerical and experimental results is achieved.
The design of a piezoelectric device aimed at harvesting the kinetic energy of random vibrations on a vehicle’s wheel is
presented. The harvester is optimised for powering a Tire Pressure Monitoring System (TPMS). On-road experiments are
performed in order to measure the frequencies and amplitudes of wheels’ vibrations. It is hence determined that the
highest amplitudes occur in an unperiodic manner. Initial tests of the battery-less TPMS are performed in laboratory
conditions where tuning and system set-up optimization is achieved. The energy obtained from the piezoelectric bimorph
is managed by employing the control electronics which converts AC voltage to DC and conditions the output voltage to
make it compatible with the load (i.e. sensor electronics and transmitter). The control electronics also manages the
sleep/measure/transmit cycles so that the harvested energy is efficiently used. The system is finally tested in real on-road
conditions successfully powering the pressure sensor and transmitting the data to a receiver in the car cockpit.
KEYWORDS: Copper, Electromechanical design, Energy harvesting, Instrument modeling, Data modeling, 3D modeling, Surface conduction electron emitter displays, Epoxies, Adhesives, Electrodes
Vibration energy harvesting devices based on piezoelectric bimorphs have attracted widespread attention. In this work experimental set-ups are developed to assess the performances of commercially available piezoelectric energy harvesters. Bending tests allow determining the equivalent bending stiffness of the scavengers. On the other hand, dynamic tests allow obtaining frequency response functions in terms of produced voltage and power outputs vs. base acceleration around the fundamental resonance frequency. The results allow determining the influence of the voltage feedback on the dynamic response of the devices, the dependence of output voltages and powers on the applied resistive loads, the values of the loads and frequencies for which the output power is maximized, as well as the comparison of the experimental data with those obtained by using the recently developed coupled electromechanical modal model. All of this creates the preconditions for the development of optimized vibration energy harvesting devices.
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