Electromagnetic Transducer Research Articles

An electromagnetic rotational energy harvester using sprung eccentric rotor, driven by pseudo-walking motion

In this work, an electromagnetic energy harvesting device using a sprung eccentric rotor has been designed, optimized and characterized to harvest power from pseudo-walking signals (a single frequency sinusoidal signal derived from motion of a driven pendulum that approximates the swing of a human-arm during walking). Our analysis shows that a rotor with an eccentric mass suspended by a torsional spring enhances the mechanical energy captured from low-frequency excitations (e.g., those produced during human walking, running/jogging). An electromagnetic transducer in the sprung eccentric rotor structure converts the captured mechanical energy into electrical energy. An electromechanical dynamic model of a sprung eccentric rotor has been developed and an optimization routine was performed to maximize output power under pseudo-walking excitation. The structure of the electromagnetic transducer was refined using Finite Element Analysis (FEA) simulations. A prototype energy harvester was fabricated and tested in a pseudo wrist-worn situation (by mounting on a mechanical swing-arm) to mimic the low-frequency excitation produced during human walking. A series of pseudo-walking motions was created by varying the swing profile (angle and frequency). The prototype with optimal spring stiffness generates a maximum 61.3 μW average power at ±25° rotational amplitude and 1 Hz frequency which is about 6-times higher than its unsprung counterpart under same excitation condition. The experimental results are in good agreement with the simulation results.

気体軸受圧力による磁気ディスク媒体及びスライダの表面変形

The slider/disk spacing of magnetic disk drives has been reduced in order to increase the recording density. Especially, the thermal flying-height control technology, where the electromagnetic transducer is protruded into the slider/disk spacing by heating the slider partially, contributes to make the flying height less than 2nm. Because of the narrower gas bearing clearance, the bearing pressure rises up to several tens times of atmospheric pressure. This pressure rise causes the deformation of slider and disk surface. The slider and disk surface deformation causes the change of gas bearing clearance and consequently the change of air bearing pressure. The pressure change causes the flying attitude. The flying characteristics also may be different from that of expected at the design, where the effect of deformation is not included. It is important to estimate correct flying characteristics affected by the deformation to realize stable flying and accurate recording. We introduced iterative method for searching the flying attitude affected by the slider/disk deformation. We obtained the air bearing pressure by solving the molecular gas lubrication equation numerically. And the simple numerical method, which utilizes the elastic half-space assumption, was employed for calculating the deformation of pressurized disk surface. The finite element method was applied to analyze the slider deformation. And the effect of deformation on the slider attitude is evaluated.

Effect of the localization on the response of a quasi-periodic electromagnetic oscillator array for vibration energy harvesting

Vibration energy harvesting by exploiting the multimodal approach in a quasi-periodic system is proposed. The quasi-periodic system, based on electromagnetic transduction, consists of two weakly coupled magnets mechanically guided by two elastic beams. Mistuning is achieved by varying the mechanical stiffness of one of the beams. These imperfections will lead to the vibration energy localization in regions close to the imperfections which will be exploited to maximize the harvested energy.

Modeling and Experiment of Electromagnetic Energy Harvester System by Using Dual Moving Mechanical Systems at Low Frequency Range.

This paper presented a concept of single degree of freedom (SDOF) electromagnetic vibration energy harvester device. This technique enable system to operate at wideband frequency range, low frequency and has multi-resonance frequencies. Each mechanical system operates at difference frequency where each system is attached with electromagnetic transducer components. the device is developed based on the parameter factors of vibration transmissibility from external vibration sources into the device through mathematical modelling. A prototype was tested by using vibration exciter and normal human walking. the fabricated device had showed multi-resonant behavior at 4.26 and 8.34 Hz during test. From experiment results, they have showed capability to operate at wide bandwidth frequency from 1.9 until 18.5 Hz at a periodic excitation of 0.04 g. the highest amount of rms voltage that has been produced about 108 mV with a maximum 78 µW average power across the 150 Ω load resistance. So, it has proven the dual-moving mechanical concept with low damping value in system has increased the operating bandwidth frequency and also increased the amount of output voltage from device.

Powerful Sources for High Frequency Electromagnetic Transducers for Measurement, Monitoring and Diagnostics

Conceptual provisions for the construction of miniaturized variable parameter of high-power high-frequency broadband radio pulse amplifiers have been developed: filling frequency, duration, significant peak current and peak voltage. A circuit-based solution is proposed for constructing high-frequency radio signal of high-power amplifiers, whose frequency varies in the interval 0.1 … 20 MHz, the time duration is 1 … 10 periods of pulse filling frequency, with an output current that reaches 200 A and voltage up to 4 kV. The use of the developed powerful amplifier will allow creating and improving the instruments for ultrasonic quality control of products by electromagnetic-acoustic transducers in industry and electromagnetic transducers in medical devices using the effect of nuclear magnetic resonance, electron paramagnetic resonance, and also in measuring devices.

A review of walking energy harvesting using piezoelectric materials

Harvesting kinetic energies is a sustainable method for generating electricity without depleting natural resources. The main mechanisms for kinetic energy harvesting are piezoelectric, electromagnetic, electrostatic or by using magnetostrictive materials. This study focuses on harvesting of walking energy and aims to compare different technologies used for converting of walking energy to electricity, and identify the most effective technology. Several types of harvester located on body of user to harvest kinetic energy of body during walking, while some pavement slabs are produced for harvesting energy. The paper concludes that the pavement equipped with the harvesters would be more reliable than the body located technologies since it is independent of the physiological parameters. Moreover, the piezoelectric transduction is more desirable due to its advantages such as simplicity and flexibility, while produce less current output than the electromagnetic transduction.

Outrigger tuned inertial mass electromagnetic transducers for high-rise buildings subject to long period earthquakes

This paper proposes outrigger tuned inertial mass electromagnetic transducer (TIMET) systems for high-rise buildings subject to long period earthquake excitations. The proposed outrigger TIMET systems consist of the outrigger and TIMET parts. The outrigger damping systems have been proposed as a novel energy dissipation approach to high-rise buildings, in which control devices are installed vertically between the outrigger and perimeter columns to achieve large energy dissipation. While the TIMET has been developed based on the mechanism of the tuned viscous mass damper (TVMD) which can improve energy absorbing capability by taking advantage of resonance effect. However, instead of a viscous material, the damping of the TIMET is provided by a motor which can convert mechanical energy to electrical energy. The focus of this study is to investigate the structural control performance and energy harvesting efficiency of the proposed outrigger TIMET system for high-rise buildings subjected to long period earthquakes through numerical simulations.

Energy generation in a hybrid harvester under harmonic excitation

A hybrid energy harvester combining piezoelectric and electromagnetic transduction mechanisms is designed to harvest vibration energy. The system comprises of a cantilever beam PZT harvester and a magnetic mass hung through a spring at the free end. The beam with PZT harvests energy using piezoelectric effect while the hanging mass oscillates through a copper coil to harvest electromagnetic energy. This paper studies power harvested from the hybrid harvester under harmonic excitation using experimental and analytical evaluations. Comparisons are made with the standalone piezoelectric and electromagnetic harvesters under similar excitation environment. The study shows that the present hybrid harvester can harvest energy at a broad range of frequencies. Furthermore, a few parametric studies are carried out to understand the device output performance. The bandwidth of the harvester and the power harvested within the bandwidth can be designed based on the stiffness of the system and also by changing the electromechanical coupling coefficient. Studies reported also show that bandwidth of harvester can also be increased by increasing the magnetic mass.

Extension of the scope of exemplary microwave power meter

Using ferrіmagnetic material as an electromagnetic transducer in mechanical energy and magnetic resonance phenomena yielded sufficient mechanical energy to rotate the harness ponderomotive wattmeter fixed at both ends by means of extensions or cores. At resonance, the moment of force is (6 ± 0,5)∙10-8 N m, which is 6∙103 times more in comparison with the moment of forces achieved in the well-known works. High-precision microwave wattmeter with sufficient mechanical strength and reliability for industrial applications have been developed. The random error in the power measurement is 0.1%.

Self-Sensing Electromagnetic Transducer for Vibration Control of Space Antenna Reflector

Space antenna reflectors are used by space vehicles to communicate with ground stations. These reflectors are generally subject to broadband random vibration and shock conditions during shipment and vehicle launch. While active vibration control methods can reduce any unexpected responses, sensors, controllers, power amplifiers, and actuators are all required to implement the control system. These additional external devices increase both the weight and the cost of the reflector, and reduce the reliability and safety of the space product. This study proposes a novel self-sensing vibration control method and applies a self-sensing electromagnetic transducer to suppress the vibration of a space antenna reflector. This transducer is used bifunctionally, acting as both an isolator and a velocity sensor. The vibration control principle of the proposed method is analyzed. A governing equation is established using the finite element method. A type of degree of freedom reduction method is used to obtain the response of the space antenna reflector. A ground experiment is then set up. The results demonstrate that the proposed self-sensing vibration control method can reduce the second-order and third-order vibrations of the space antenna reflector by 4 and 9 dB, respectively.

Sound wave propagation on the human skull surface with bone conduction stimulation

BackgroundBone conduction (BC) is an alternative to air conduction to stimulate the inner ear. In general, the stimulation for BC occurs on a specific location directly on the skull bone or through the skin covering the skull bone. The stimulation propagates to the ipsilateral and contralateral cochlea, mainly via the skull bone and possibly via other skull contents. This study aims to investigate the wave propagation on the surface of the skull bone during BC stimulation at the forehead and at ipsilateral mastoid. MethodsMeasurements were performed in five human cadaveric whole heads. The electro-magnetic transducer from a BCHA (bone conducting hearing aid), a Baha® Cordelle II transducer in particular, was attached to a percutaneously implanted screw or positioned with a 5-Newton steel headband at the mastoid and forehead. The Baha transducer was driven directly with single tone signals in the frequency range of 0.25–8 kHz, while skull bone vibrations were measured at multiple points on the skull using a scanning laser Doppler vibrometer (SLDV) system and a 3D LDV system. The 3D velocity components, defined by the 3D LDV measurement coordinate system, have been transformed into tangent (in-plane) and normal (out-of-plane) components in a local intrinsic coordinate system at each measurement point, which is based on the cadaver head's shape, estimated by the spatial locations of all measurement points. ResultsRigid-body-like motion was dominant at low frequencies below 1 kHz, and clear transverse traveling waves were observed at high frequencies above 2 kHz for both measurement systems. The surface waves propagation speeds were approximately 450 m/s at 8 kHz, corresponding trans-cranial time interval of 0.4 ms. The 3D velocity measurements confirmed the complex space and frequency dependent response of the cadaver heads indicated by the 1D data from the SLDV system. Comparison between the tangent and normal motion components, extracted by transforming the 3D velocity components into a local coordinate system, indicates that the normal component, with spatially varying phase, is dominant above 2 kHz, consistent with local bending vibration modes and traveling surface waves. ConclusionBoth SLDV and 3D LDV data indicate that sound transmission in the skull bone causes rigid-body-like motion at low frequencies whereas transverse deformations and travelling waves were observed above 2 kHz, with propagation speeds of approximately of 450 m/s at 8 kHz.

Electromagnetic Transduction Therapy for Achilles Tendinopathy: A Preliminary Report on a New Technology

A parallel prospective feasibility study was performed on 53 patients with chronic mid-portion Achilles tendinopathy (age 44.7 ± 9.1 years). Of the 53 patients, 28 (active group) were treated using a new electromagnetic (pulsed electromagnetic field) transduction therapy device (Cellactor® MT1) and heel cushions. The device produces an electromagnetic field of 80 milliTesla; a total of 8 treatments was performed within 4 weeks in an outpatient setting, without anesthesia, immobilization, or rest. A control group of 25 patients with a similar duration of symptoms was treated with heel cushions only. At the 12-week assessment point, the visual analog scale scores in both groups had significantly decreased, although the active group had significantly improved visual analog scale scores compared with those of the controls. The Role-Maudsley scores had also significantly improved in both the active and the control groups (p < .00001 and p = .0002, respectively). Electromagnetic transduction therapy could potentially be a useful modality for the treatment of Achilles tendinopathy. It should be compared with the current reference standard of extracorporeal shockwave therapy/radial soundwave therapy with similar level I, II, and III studies.

Probabilistic distribution and stochastic P-bifurcation of a hybrid energy harvester under colored noise

In this manuscript, a hybrid energy harvesting system combining piezoelectric and electromagnetic transduction and subjected to colored noise is investigated. By using the stochastic averaging method, the stationary probability density functions of amplitudes are obtained and reveal interesting dynamics related to the long term behavior of the device. From stationary probability densities, we discuss the stochastic bifurcation through the qualitative change which shows that noise intensity, correlation time and other system parameters can be treated as bifurcation parameters. Numerical simulations are made for a comparison with analytical findings. The Mean first passage time (MFPT) is numerical provided in the purpose to investigate the system stability. By computing the Mean residence time (TMR), we explore the stochastic resonance phenomenon; we show how it is related to the correlation time of colored noise and high output power.

The Vibrant Soundbridge® middle ear implant: A historical overview

Objective: To present a historical overview of the Vibrant Soundbridge® (VSB) middle ear implant (MEI), since its beginning in the 1990s to date and to describe its course and contemplate what it might become in the future.History: MEIs started to take form in researchers’ mind in the 1930s with the first experiment of Wilska. In the 1970s, several devices, such as the Goode and Perkins’, the Maniglia’s, or the Hough and Dormer’s were created but remained prototypes. It is only in the 1990s the devices that emerged remained on the market. In 1994, Symphonix, Inc. was created and aimed to manufacture and commercialize its semi-implantable MEI, the VSB. The principle of the VSB lies on a direct drive of the sound to a vibratory structure of the middle ear through an electromagnetic transducer, the floating mass transducer (FMT). The particularity of the system VSB is the simplicity of the transducer which is made of both the magnet and the coil; thus, the FMT, fixed on a vibrating middle ear structure, mimics the natural movement of the ossicular chain by moving in the same direction. The goal of the VSB was to give an alternative to patients with mild-to-severe sensorineural hearing loss who could not wear hearing aids (HAs) or who were unsatisfied conventional HA users. Subsequent to Tjellström’s experiment in 1997, implantations started to include etiologies such as otosclerosis, radical mastoidectomy, failed ossiculoplasty/tympanoplasty, and atresia.Nowadays, the VSB, with more than 20 years of experience, is the oldest and most used middle ear implant worldwide. It is well acknowledged that the straightforward design and reliability of the transducer have certainly contributed to the success of the device.

Structural control with tuned inertial mass electromagnetic transducers

Summary This paper investigates the validity of the tuned inertial mass electromagnetic transducer (TIMET) applied to building structures subjected to seismic motions. The TIMET is a device inspired by two innovative structural control devices proposed recently, that is, tuned viscous mass damper and electromagnetic transducer. The TIMET consists of a spring, an inertial mass produced by a ball screw mechanism, and an electromagnetic transducer part composed of a motor and an electrical circuit. The stiffness of the spring is tuned such that the inertial mass resonates with the vibrating building. This makes the motor installed in parallel with the inertial mass run up in an efficient way, and the vibration energy is converted to electrical energy effectively. As a result, vibration of the building decays fast and electrical energy is stored. This generated energy that is reusable for the self-powered control systems, structural health monitoring, emergency power source, and so on. In this paper, through numerical simulation studies employing the scaled three-story building model proposed for benchmark studies, the vibration reduction and energy harvesting capabilities of the TIMET is explored and the application potentiality to civil structures is discussed.

Sensorless parameter estimation of electromagnetic transducer considering eddy currents

This paper presents a method of estimating the parameters of an electromagnetic transducer without sensors. The proposed method utilizes the measured admittance of the electromagnetic transducer, and therefore position, velocity, and/or acceleration sensors are not necessary in this framework. Novel impedance models are proposed based on the basic physical principles of electromagnetics; in particular, the effect of eddy currents has been included in these proposed models. The validity of the proposed estimation method and models was experimentally demonstrated by comparing the parameter estimation and vibration control capabilities of the proposed models with three conventional models.

Electromagnetic transduction therapy in non-specific low back pain: A prospective randomised controlled trial

ObjectivesA prospective randomised controlled trial to investigate the efficacy of electromagnetic transduction therapy (EMTT) for treatment of patients with non-specific low back pain. DesignTwo groups with non-specific low back pain were either treated with conventional therapy alone over 6 weeks or in combination with 8 sessions of EMTT. ResultsIn both intervention groups the low back pain related pain and the degree of disability decreased significantly at follow-up visits. Combination of EMTT and conventional therapy proved significant superior to conventional therapy alone. ConclusionEMTT is a promising treatment in patients with non-specific low back pain.

Asymmetric arc‐shaped vortex‐induced electromagnetic generator for harvesting energy from low‐velocity flowing water

In this study, a novel small-scale electromagnetic energy harvester is designed and optimised, which aims at addressing the limitations of existing approaches in output power scavenged from low-velocity flowing water. Instead of conventional cantilever beams, an asymmetric arc-shaped elastic beam is implemented to disrupt flow, leading to its oscillation in the induced unsteady flow field. An electromagnetic transducer is utilised to convert kinetic energy into electrical energy. Furthermore, the effects of the structure asymmetry and curvature on the electrical outputs are investigated to optimise the scavenging energy capability. A prototype with the volume of 152.4 cm3 is fabricated and tested. A maximum open-circuit voltage of 1440 mV is obtained at 0.409 m/s, and the harvester generates an output power of 0.503 mW when it is connected to an external load of 110 Ω. The small-scale harvester shows great potential for applying in wireless sensor networks.

Numerical simulations of aeroelastic instabilities to optimize the performance of flutter-based electromagnetic energy harvesters

The article presents a two-dimensional fully coupled fluid–structure interaction model for simulating aeroelastic instabilities to evaluate and optimize the performance of flutter-based electromagnetic energy harvesters. The flutter-type unstable vibration of T-shaped cantilever systems is investigated as a driving mechanism for small-scale energy conversion. A flow solver based on the vortex particle method and a structural solver based on a corotational finite element formulation are coupled in order to accurately account for the geometrically nonlinear effects of such very flexible elements. A reference harvester is simulated considering the damping effects arising from the electromagnetic transducer. The estimated flutter wind speed and the predicted energy outputs under different electrical resistances are found to agree reasonably well with reference wind tunnel experiments. The influence of physical parameters such as length, thickness, and cantilever tip height on the performance of the harvester is investigated up to an envelope volume of 42 cm3. The maximum power output is found to be 5.3 mW at 8 m/s. The optimized harvester shows a better performance under low wind speeds by producing 0.65 mW at 4 m/s where the reference harvester produced no power.

Tumor-Treating Fields: Nursing Implications for an Emerging Technology .

Tumor-treating fields (TTFields) are a new technology used for cancer treatment consisting of battery-powered, insulated electromagnetic transducers that are placed on the scalp. This wearable, adhesive device is a certified physician-prescribed therapy for patients with glioblastoma multiforme, a type of primary brain cancer. TTFields are being used concomitantly with temozolomide (Temodar®) in patients with newly diagnosed glioblastoma and as a monotherapy in patients with recurrent glioblastoma after radiation therapy and chemotherapy. Nursing professionals caring for patients using this emerging technology should be able to educate patients regarding proper use of TTFields and monitor for side effects. .