This paper presents the concept design, preliminary experimental validation, and performance evaluation of a novel bio-inspired bi-stable piezoelectric energy harvester for self-powered fish telemetry tags. The self-powered fish tag is designed to externally deploy on fish (dorsal fin) to track and monitor fish habitats, population, and underwater environment, meanwhile, harvests energy from fish motion and surrounding fluid flow for a sustainable power supply. Inspired by the rapid shape transition of the Venus flytrap, a bi-stable piezoelectric energy harvester is developed to generate electricity from broadband excitation of fish maneuvering and fluid. A bluff body is integrated to the free end of the bistable piezoelectric energy harvester to enhance the structure-fluid interaction for the large-amplitude snap-through vibrations and higher voltage output. Controlled laboratory experiments are conducted in a water tank on the bio-inspired bi-stable piezoelectric energy harvester using a servo motor system to simulate fish swing motion at various conditions to evaluate the power generation performance. The preliminary underwater experimental results demonstrated that the proposed bio-inspired bi-stable piezoelectric effectively converters fish swing motions into electricity. The average power output of 1.5 mW was achieved at the swing angle of 30° and frequency of 1.6 Hz.
Many researchers have been focused on energy harvester for the tire over the past decade. In this paper, we propose a self-tuning stochastic resonance energy harvester for a smart tire with the circuit integration. Compared to existing harvesters, the energy harvester shows large power and wide bandwidth due to stochastic resonance and passive selftuning. The harvester consists of an inward rotating cantilever beam with an electromagnetic transducer. The tuning performance is verified by analysis of Kramers rate and signal-to-noise ratio (SNR). In addition to energy harvester, we implemented the energy harvesting circuit to achieve data acquisition and energy storage. Circuit includes a rectifier, buck-boost converter, wireless communication module, microprocessor and temperature monitoring sensor. In lab test and field test are conducted to performance of self-tuning energy harvester. Circuit assembly is attached to the rim hub while harvester assembly is installed inside the tire with a tire pressure monitoring sensor (TPMS). The results the feasibility of the self-tuning harvesting strategy on the smart tire application.
In vibration energy harvesting systems, mechanical damping is reduced to minimum to get large electrical power output. However, small mechanical damping will result in a narrow bandwidth in the frequency domain. This will lead to non-ideal performance when the excitation frequency does not match with the natural frequency. In human body energy harvesting backpack, the human comfort will also have to take into consideration besides harvesting power. In this paper, we proposed an electrical damping tuning method for energy harvesting backpack. The electrical damping will change according to the excitation frequency to achieve high power output at lower frequency. In this way, the frequency bandwidth increases. At resonance and high frequency, the damping will be tuned to control the maximum stroke of the backpack. This will make the wearer feel comfortable while substantial power is harvested. The electrical damping tuning circuit senses the input frequency and tunes the electrical damping accordingly. The circuit design and the control strategy are described in detail. Experiment will be done to validate the design goals.
This paper performs a design parameter study for development of a self-powering brain neurostimulation system by harvesting deformation energy generated from mandibular (lower jaw) movements. For decades, scientists recognized that electrical stimulation of the brain (deep brain stimulation, DBS) has the potential to treat a variety of refractory medical conditions including chronic pain, Parkinson’s disease, movement disorders, major depression and epilepsy. A commercial DBS device comprise a stimulation lead, neurostimulation unit with microcontroller, and a battery for power supply. The batteries in DBS need replacement every 3~5 years and thus problematic because additional surgery is required to replace them. This paper describes an innovative technology to power DBS by converting stresses/strains in the mandible caused by jaw movements into electrical energy using piezoelectricity. The proposed energy harvester has a multilayer layout composed of piezoelectric composite and biocompatible titanium layers, and will be secured in place on the body of the mandible using titanium screws. For optimal design of this harvester, we build an experimentally verified FEM model for the mandible and harvester assembly, and perform parameter study of the energy harvester. The parameter study on the size/location of the piezoelectric material as well as its cross sectional properties of piezoelectric harvester is performed and experimentally tested. Its practical use by integrating it with electrical circuit is also discussed.
A wireless structure health monitoring (SHM) system for wind turbine blades has been actively researched to realize its low cost and efficient maintenance. A sustainable power supply to the wireless SHM system installed in a rotating blade has been one of the most challenging issue. Vibration energy harvesting via piezoelectricity or electromagnetism can provide a solution, but varied blade rotation and the corresponding random natured vibration make it difficult to design a practical harvester. In this paper, an impact-driven piezoelectric energy harvester (PEH) is proposed to efficiently generate an electric power at PEH’s natural frequency for any rotation speed of blades. This harvester can be installed within the blade to power the wireless SHM system sustainably. The impact-driven PEH consists of a piezoelectric cantilever beam and a gravity-induced rotator. When the wind turbine blade rotates, the orientation of the cantilever changes but the orientation of the gravity-induced rotator remains fixed to a global coordinate system (defined on the earth). At every rotation cycle, the gravity-induced rotator strikes the cantilever tip, which causes vibration. Then, the piezoelectric cantilever beam generates electric power at PEH’s natural frequency. A testing setup for the proposed PEH is built, by installing the PEH prototype on the blades driven by a DC motor. Experimental result shows that the proposed PEH generates electric power at PEH’s natural frequency for any rotation speed, and average power generated from the proposed PEH is 1.56 mW at the typical blade’s rotation speed of 20 RPM.
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