Chunchen Zhang

Harvesting magnetic energy using extensional vibration of laminated magnetoelectric plates

Magnetically forced extensional vibrations of laminated plates with piezoelectric and piezomagnetic layers are analyzed theoretically. It is shown that such a structure can be used to harvest magnetic energy and convert it to electric energy. The output power and the energy conversion efficiency are calculated. The load dependence of the magnetoelectric coupling coefficient is also obtained.

A wideband magnetic energy harvester

A wideband magnetic energy harvester is proposed by using a number of multiferroic composite fibers of different lengths which are connected in parallel or series. The structural theory is employed to characterize the magnetoelectroelastic behavior of the fibers. A global circuit analysis is then performed. It is shown that such a structure of energy harvester is capable of collecting the ambient magnetic energy over a wide frequency range.

The Magnetoelectric Effects in Multiferroic Composite Nanofibers

In this letter, we analyze the quasistatic and dynamic magnetoelectric responses of multiferroic composite nanofibers consisting of both ferroelectric and ferromagnetic phases and demonstrate that the nanofibers exhibit magnetoelectric responses orders of magnitude higher than multiferroic composite thin films of similar compositions. The analysis suggests that the multiferroic nanofibers are promising for magnetoelectric applications.

One-dimensional equations for piezoelectromagnetic beams and magnetoelectric effects in fibers

We derive one-dimensional equations for the extension and flexure with shear deformation of a piezoelectromagnetic beam with rectangular cross section from three-dimensional equations. The equations obtained are used to analyze magnetoelectric effects in fibers of piezoelectric/piezomagnetic composites. Both static magnetoelectric effects and frequency-dependent magnetoelectric effects in time-harmonic motions are examined. Various material and field orientations are considered. We also make comparisons between magnetoelectric effects in fibers and in thin films on substrates. Two-dimensional equations for laminated piezoelectric/piezomagnetic plates are used in the analysis of the thin films. It is found that magnetoelectric effects in fibers are significantly stronger than those in thin films on substrates.

Propagation of extensional waves in a piezoelectric semiconductor rod

We studied the propagation of extensional waves in a thin piezoelectric semiconductor rod of ZnO whose c-axis is along the axis of the rod. The macroscopic theory of piezoelectric semiconductors was used which consists of the coupled equations of piezoelectricity and the conservation of charge. The problem is nonlinear because the drift current is the product of the unknown electric field and the unknown carrier density. A perturbation procedure was used which resulted in two one-way coupled linear problems of piezoelectricity and the conservation of charge, respectively. The acoustic wave and the accompanying electric field were obtained from the equations of piezoelectricity. The motion of carriers was then determined from the conservation of charge using a trigonometric series. It was found that while the acoustic wave was approximated by a sinusoidal wave, the motion of carriers deviates from a sinusoidal wave qualitatively because of the contributions of higher harmonics arising from the originally n...

Continuous micron-scaled rope engineering using a rotating multi-nozzle electrospinning emitter

Electrospinning (ES) enables simple production of fibers for broad applications (e.g., biomedical engineering, energy storage, and electronics). However, resulting structures are predominantly random; displaying significant disordered fiber entanglement, which inevitably gives rise to structural variations and reproducibility on the micron scale. Surface and structural features on this scale are critical for biomaterials, tissue engineering, and pharmaceutical sciences. In this letter, a modified ES technique using a rotating multi-nozzle emitter is developed and utilized to fabricate continuous micron-scaled polycaprolactone (PCL) ropes, providing control on fiber intercalation (twist) and structural order. Micron-scaled ropes comprising 312 twists per millimeter are generated, and rope diameter and pitch length are regulated using polymer concentration and process parameters. Electric field simulations confirm vector and distribution mechanisms, which influence fiber orientation and deposition during the process. The modified fabrication system provides much needed control on reproducibility and fiber entanglement which is crucial for electrospun biomedical materials.

Stable single device multi-pore electrospraying of polymeric microparticles via controlled electrostatic interactions

This work demonstrates a facile fabrication method to produce high throughput biodegradable microparticles (MPs) using a flute-like multi-pore emitter device in place of conventional single needle electrospraying capillaries. By manipulating the configuration of the emitter and the processing parameters, uniform microparticles are successfully sprayed in a single step for large-scale production. Furthermore, by manipulating individual spatial pore location various jet-bending interactions, which give rise to particle variations and irregularities, are overcome. Finally, findings correlate well with models reported by Hartman.

Magnetoelectric Effects in Multiferroic Bilayers for Coupled Flexure and Extension

Magnetoelectric (ME) effects in two configurations of piezomagnetic/piezoelectric bilayers in coupled flexure and extension are studied. Static and frequency-dependant ME effects are obtained. Compared to the ME effects in pure extension of multiferroic plates, the ME effects in the coupled motion are twice as high in static cases and three times as high in harmonic motions.

Through-wall Power Transmission Using an Alternating Magnetic Field and a Multiferroic Energy Harvester

We propose to use a magnetic field energy harvester to collect the energy in an alternating magnetic field penetrating an elastic wall. The multiferroic energy harvester consists of a piezomagnetic layer for collecting magnetic energy and a piezoelectric layer for conversion to electric energy. A theoretical analysis is performed using the linear equations for piezomagnetic, piezoelectric, and elastic materials. The output voltage, power, and efficiency are calculated. The effects of various physical and geometric parameters are examined. It is found that the electric output is sensitive to these parameters, and design optimization is needed. Significant output can be achieved near a few resonant frequencies of the structure.

Janus particle synthesis via aligned non-concentric angular nozzles and electrohydrodynamic co-flow for tunable drug release

A novel non-concentric, symmetrical spinneret possessing aligned nozzles with angular outlets was designed and manufactured. The device was used to synthesize Janus particles by atomizing co-flowing formulations at relatively high electric fields (up to ∼15 kV). By manipulating the nozzle outlet angle (θ), the maximum applied voltage permitting stable co-jetting was enhanced; enabling the production of finer droplets and, thus, microparticles. Furthermore, non-concentric co-flow, process optimization and stable atomization yielded Janus particles with distinct morphological features which were then used to demonstrate tunable drug release.