Characterization of Polyvinylidene Difluoride-based Energy Harvesting with IDE Circuit Flexible Cantilever Beam

Piezoelectric energy harvesting is the process of extracting electrical energy using energy harvester devices. Any stress in the piezoelectric material will generate induced voltage. Previous energy harvester device with stiff cantilever beam was generated low harvested energy. A flexural piezoelectric energy harvester is proposed to improve the generated harvesting energy. Polyvinylidene difluoride is a polymer piezoelectric material attached to a flexible circuit made of polyimide. Four interdigitated electrode circuits were designed and outsourced for fabrication. The polyvinylidene difluoride was then attached to the interdigitated electrode circuit, and a single clear adhesive tape was used to bind them. Four piezoelectric energy harvesters and ultrasonic ceramic generators were experimentally tested using a sieve shaker. The sieve shaker contains a two-speed oscillator, with M1=0.025 m/s and M2=0.05 m/s. It was used to oscillate the energy harvester devices. The resulting induced voltages were then measured. Design 4, with the widest width of electrode fingers and the widest gap between electrode fingers, had the highest power generated at an output load of 0.745 µW with the M2 oscillation speed. The oscillation speed of the sieve shaker impacted the energy harvester devices as a higher oscillation speed gave higher generated power.

Piezoelectric Unimorph and Bimorph Cantilever Configurations: Design Guidelines and Strain Assessment

Multi-stable configurations of piezoelectric harvesters are quite successful in achieving the two important goals, the broadband frequency response and large orbit oscillations exhibiting periodic, multi-periodic, and chaotic solutions. However, in the quest of achieving large amplitude broadband frequency response, assessment of induced strain levels considering the limits on the strain in piezoelectric material has received minimal attention. In this context, the investigation presents an analytical formulation for the assessment of induced strain and voltage(s) in piezoelectric unimorph and bimorph cantilevers. The formulation quantifies not only the induced voltage(s) in individual piezoelectric layers of a bimorph, but also the equivalent voltages in parallel and series connection modes, respectively. Also, while computing the induced voltage in the first piezoelectric layer, the contribution from the induced voltage of the second piezoelectric layer to the acting bending moment is captured in the formulation. The formulations are validated through the experiments and results from the literature. Further, we have applied two practically useful normalization schemes, the tp- and tt-normalizations to the analytical expressions. Using the two normalization schemes, influences of variation of substrate and adhesive layer thicknesses, elastic moduli of layers, and substrate-to-composite length fraction are visualized and discussed. Based on the results, summarized guidelines for design and selection of geometric and material parameters are presented, which are also applicable for other sensing and actuation applications. At last, practically suitable ranges and optimum values for the normalized design variables are proposed.

Innovative Construction of the AFPM-Type Electric Machine and the Method for Estimation of Its Performance Parameters on the Basis of the Induction Voltage Shape

The article presents an innovative construction of the Axial Flux Permanent Magnet (AFPM) machine designed for generator performance, which provides the shape of induced voltage that enables estimation of the speed and rotational angle of the machine rotor. Design solutions were proposed, the aim of which is to limit energy losses as a result of the occurrence of eddy currents. The method of direct estimation of the value of the rotational speed and rotational angle of the machine rotor was proposed and investigated on the basis of the measurements of induced voltages and machine phase currents. The advantage of the machine is the utilization of simple and easy-to-use computational procedures. The acquired results were compared with the results obtained for estimation performed by using the Unscented Kalman Filter (UKF).

Intracranial Electric Field Recording During Multichannel Transcranial Electrical Stimulation

Background: Multichannel transcranial electrical stimulation (tES) modeling and optimization have been widely studied in recent years. Its theoretical bases include quasi-static assumption and linear superposition. However, there is still a lack of direct in vivo evidence to validate the simulation model and theoretical assumptions. Methods: We directly measured the multichannel tES-induced voltage changes with implanted stereotactic-electroencephalographic (sEEG) electrodes in 12 epilepsy subjects. By combining these measured data, we investigate the linear superposition and prediction accuracy of simulation models for multi-electrode stimulation and further compare the induced EF differences between transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS). Results: Our in vivo measurements demonstrated that the multi-electrode tES-induced voltages were almost equal to the sum of the voltages generated independently by bipolar stimulation. Both measured voltages and electric fields obtained in vivo were highly correlated with the predicted values in our cohort (Voltages: r = 0.92, p < 0.001; electric fields: r = 0.74, p < 0.001). Under the same stimulation intensity, the tDCS-induced peak-zero voltages were highly correlated with the values of tACS (r = 0.99, p < 0.001; s = 0.99). Conclusions: The in vivo measurements provides confirmatory results for linear superposition and quasi-static assumption within the human brain. Furthermore, we found that the individualized simulation model reliably predicted the multi-electrode tES-induced electric fields.

Attractive Force Estimation of a Magnetic Adsorption Unit for Inspection UAVs

This paper presents an attractive force estimation system and an automatic activation system for an electropermanent magnet (EPM) for an inspection UAV. Adsorption to infrastructures for inspection at a distance is extremely difficult to perform safely because the operator cannot detect the state of adsorption of the drone equipped with a magnetic adsorption device. Therefore, in this paper, we clarify the relationship between the magnetic flux density and attractive force of the EPM through experiments, and develop an estimation algorithm for the attractive force based on the results. An automatic activation system, using the induced voltage in the coil when the EPM approaches the magnetic substance, is developed and mounted on a quadrotor for a flight experiment along with the estimation system for the attractive force. The developed system is verified using flight and adsorption experiments on the quadrotor.

Analysis of Induced Voltage on Pipeline Located Close to Parallel Distribution System

Gas and oil pipelines are widely used to supply customers. They are often laid in parallel with high voltage power lines, sharing right of way. When the pipeline is located near overhead high-voltage power, corrosion caused by induced voltages from AC power lines can occur in utility pipelines. Therefore, the calculation of induced voltage is always required for both interference and maintenance workers as well as pipeline facility safety. For parallel distribution lines, the calculation method for the induced voltage is not suitable due to the excessive error caused by using the screening factors of the neutral current. For a more practical analysis of the induced voltage, a new analysis is needed using the actual neutral current and which also considers the overhead ground conductor and the neutral conductor. This paper analyzed the induced voltage from a parallel distribution system using Carson’s formula and vector analysis. Simulation analysis results are verified by separate Electromagnetic Transient Program (EMTP) simulation.

Surface-Integrated Electric Field Sensor for the Detection of High-Voltage Power Lines

When a drone is used for inspection of facilities, there are often cases in which high-voltage power lines interfere, resulting in the drone being caught or falling. To prevent this type of incident, drones must be capable of detecting high-voltage power lines. Typically, a strong electric field is formed around the high-voltage lines. To detect the electric fields around high-voltage lines, this study proposes an electric field sensor that may be integrated within the body of a drone. In a laboratory environment, a voltage of 25 kV was applied to an overhead line, and the induced voltage in the proposed sensor was measured at various electric field intensities. Over an electric field range of 0.5 to 10.1 kV/m, a voltage of 0 to 0.77 V was measured with each proposed sensor. In addition, the electric field and the voltage induced in the sensor were measured in a real-world railway environment with overhead lines. Under these conditions, the proposed sensor has the compensated value of 4.5 when the measured electric field was 4.05 kV/m. Therefore, the proposed sensor may be applied in drones to measure large electric fields and to detect the presence of high-voltage lines in its vicinity.

Ultrafast Deep-Ultraviolet Laser-Induced Voltage Response of Pyrite

Ultrafast, high-sensitivity deep-ultraviolet (UV) photodetectors are crucial for practical applications, including optical communication, ozone layer monitoring, flame detection, etc. However, fast-response UV photodetectors based on traditional materials suffer from issues of expensive production processes. Here, we focused on pyrite with simultaneously cheap production processes and ultrafast response speed. Nanoseconds photovoltaic response was observed under UV pulsed laser irradiation without an applied bias at room temperature. In addition, the response time of the laser-induced voltage (LIV) signals was ~20 ns, which was the same as the UV laser pulse width. The maximum value of the responsivity is 0.52 V/mJ and the minimum value of detectivity was about to ~1.4 × 1013 Jones. When there exists nonuniform illumination, a process of diffusion occurs by which the carriers migrate from the region of high concentration toward the region of low concentration. The response speed is limited by a factor of the diffusion of the carriers. With an increment in laser energy, the response speed of LIV is greatly improved. The high response speed combined with low-cost fabrication makes these UV photodetectors highly attractive for applications in ultrafast detection.