Key Laboratory for Optoelectronic Technology and Systems

Chongqing, China

Key Laboratory for Optoelectronic Technology and Systems

Chongqing, China
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Yu H.,Chongqing University | Yu H.,Key Laboratory for Optoelectronic Technology and Systems | Yu H.,National Key Laboratory of Fundamental Science of Micro Nano Device and System Technology | Zhou J.,Chongqing University | And 3 more authors.
Sensors (Switzerland) | Year: 2014

To take advantage of applications where both light and vibration energy are available, a hybrid indoor ambient light and vibration energy harvesting scheme is proposed in this paper. This scheme uses only one power conditioning circuit to condition the combined output power harvested from both energy sources so as to reduce the power dissipation. In order to more accurately predict the instantaneous power harvested from the solar panel, an improved five-parameter model for small-scale solar panel applying in low light illumination is presented. The output voltage is increased by using the MEMS piezoelectric cantilever arrays architecture. It overcomes the disadvantage of traditional MEMS vibration energy harvester with low voltage output. The implementation of the maximum power point tracking (MPPT) for indoor ambient light is implemented using analog discrete components, which improves the whole harvester efficiency significantly compared to the digital signal processor. The output power of the vibration energy harvester is improved by using the impedance matching technique. An efficient mechanism of energy accumulation and bleed-off is also discussed. Experiment results obtained from an amorphous-silicon (a-Si) solar panel of 4.8 × 2.0 cm2 and a fabricated piezoelectric MEMS generator of 11 × 12.4 mm2 show that the hybrid energy harvester achieves a maximum efficiency around 76.7%. © 2014 by the authors; licensee MDPI, Basel, Switzerland.


Yun J.,Southwest University | Yun J.,Chongqing University | Li P.,Chongqing University | Li P.,Key Laboratory for Optoelectronic Technology and Systems | And 2 more authors.
2011 International Conference on Multimedia Technology, ICMT 2011 | Year: 2011

An improved geodesic active contour model for the detection of object boundaries is presented. A geodesic active contour model is based on an active contour evolving in time. The geodesic active contour model has a serious weakness, that is, it stops at a local minimum where there is a deep concave boundary in an image. The generalized geodesic active contour model makes an active contour convergent to long, thin boundary indentations by introducing a shrinkage force. In this paper, we present an improved geodesic active contour model based on the generalized geodesic active contour with an error term. Experimental results show that the proposed model works successfully for concave objects, it can not only detect object boundaries, but also improve double rings. The convergence rate is faster, the robust is better than the generalized geodesic active contour model. © 2011 IEEE.


Yu H.,Chongqing University | Yu H.,Key Laboratory for Optoelectronic Technology and Systems | Yu H.,National Key Laboratory of Fundamental Science of Micro Nano Device and System Technology | Zhou J.,Chongqing University | And 8 more authors.
Sensors (Switzerland) | Year: 2014

This paper presents a micro-electro-mechanical system (MEMS) piezoelectric power generator array for vibration energy harvesting. A complete design flow of the vibration-based energy harvester using the finite element method (FEM) is proposed. The modal analysis is selected to calculate the resonant frequency of the harvester, and harmonic analysis is performed to investigate the influence of the geometric parameters on the output voltage. Based on simulation results, a MEMS Pb(Zr,Ti)O3 (PZT) cantilever array with an integrated large Si proof mass is designed and fabricated to improve output voltage and power. Test results show that the fabricated generator, with five cantilever beams (with unit dimensions of about 3 × 2.4 × 0.05 mm3) and an individual integrated Si mass dimension of about 8 × 12.4 × 0.5 mm3, produces a output power of 66.75 μW, or a power density of 5.19 μW•mm-3•g-2 with an optimal resistive load of 220 kΩ from 5 m/s2 vibration acceleration at its resonant frequency of 234.5 Hz. In view of high internal impedance characteristic of the PZT generator, an efficient autonomous power conditioning circuit, with the function of impedance matching, energy storage and voltage regulation, is then presented, finding that the efficiency of the energy storage is greatly improved and up to 64.95%. The proposed self-supplied energy generator with power conditioning circuit could provide a very promising complete power supply solution for wireless sensor node loads. © 2014 by the authors; licensee MDPI, Basel, Switzerland.


Yu H.,Chongqing University | Zhou J.,Key Laboratory for Optoelectronic Technology and Systems | Wang W.,National Key Laboratory of Fundamental Science of Micro Nano Device and System Technology
2014 IEEE International Conference on Electron Devices and Solid-State Circuits, EDSSC 2014 | Year: 2014

The paper presents a new hybrid micro piezoelectric-electromagnetic generator for vibration energy harvesting, which generates energy from low frequency and small amplitude vibration environment, using piezoelectric and electromagnetic conversion mechanisms. The paper outlines factors needed when designing the hybrid energy harvester, including the coupling mathematical model, the finite element analysis, optimization procedure and trade-offs. The proposed hybrid energy harvester is also fabricated and experimental results show that the device can generate an open-circuit voltage of 4.32V and produce a power of 13.47μW with an optimal resistive load of 403KΩ at 0.1 m/s2 acceleration and 105.2 Hz frequency. © 2014 IEEE.


Yu H.,Chongqing University | Yang S.,Key Laboratory for Optoelectronic Technology and Systems | Wang W.,National Key Laboratory of Fundamental Science of Micro Nano Device and System Technology
2014 IEEE International Conference on Electron Devices and Solid-State Circuits, EDSSC 2014 | Year: 2014

The paper proposes a complete energy harvesting solution integrated with a low-loss AC/DC rectifier and a high efficiency low dropout regulator (LDO) optimized for micro piezoelectric energy harvester. The AC/DC module converts AC into DC and then supplies power for the following LDO circuit module, through which the whole chip can obtain a stable 3.3V output voltage. A dynamic compensation mechanism is presented to improve the loop stability of LDO, which is easier to achieve high phase margin than traditional compensation strategy. The simulation results of LDO indicate that the typical dropout is 0.4mV with 1mA load current and 61mV with 150mA load current respectively, and the typical voltage line regulation error is 0.025%/V. In addition, the typical load regulation error was 0.00018%. The results demonstrate that the proposed chip meets the requirements of power supply for wireless sensor node (WSN). © 2014 IEEE.


Dai X.,Key Laboratory for Optoelectronic Technology and Systems | Dai X.,Chongqing University | Wen Y.,Key Laboratory for Optoelectronic Technology and Systems | Wen Y.,Chongqing University | And 6 more authors.
Sensors and Actuators, A: Physical | Year: 2011

This paper describes an energy harvester employing multiple Terfenol-D/Pb(Mg1/3Nb2/3)O3-PbTiO 3/Terfenol-D laminate magnetoelectric transducers to convert ambient mechanical vibration into electrical energy. The harvester uses four magnets arranged on the free end of a cantilever beam. The multiple transducers are placed in the air gap between the magnets. The optimal initial positions of the transducers at the static equilibrium are analyzed. And the output characteristics of the harvester employing various numbers of transducers are experimentally studied. Experimental results indicate that the harvester employing multiple transducers can provide higher power and power density. The harvester employing four transducers produces a maximum output power of 7.13 mW, which is 3.95 times higher than that of the harvester employing a single transducer, and the harvester employing two transducers produces a maximum output power of 4.07 mW, which is 1.83 times higher than that of the harvester employing a single transducer. © 2010 Published by Elsevier B.V. All rights reserved.


Yang J.,Key Laboratory for Optoelectronic Technology and Systems | Yang J.,Chongqing University | Wen Y.,Key Laboratory for Optoelectronic Technology and Systems | Wen Y.,Chongqing University | And 4 more authors.
Sensors and Actuators, A: Physical | Year: 2011

Magnetoelectric (ME) transducers were originally intended for magnetic field sensors but have recently been used in vibration energy harvesting. In order for vibration energy harvesters to be effective over a range of vibration frequencies, recently many technologies have been investigated to broaden the frequency range of the harvesters using piezoelectric, electromagnetic and electrostatic transductions, but few have been studied that use ME transducers. This paper presents a new broadband vibration energy harvester using ME transducer, which takes advantage of multi-cantilever beams and nonlinear behavior of the magnetic force to expand the working bandwidth in ambient low frequency vibration. And a theoretical model is developed to analyze the non-sinusoidal proof mass motion and the electrical-output performances of the harvester. The experimental results show that the harvester has a bandwidth of 5.4 Hz and power density of 0.2-0.56 mW/cm3 over the entire frequency range under an acceleration of 0.2 g (with g = 9.8 ms-2). Copyright © 2011 Published by Elsevier B.V. All rights reserved.


Yu M.,Key Laboratory for Optoelectronic Technology and Systems | Wang S.,Chongqing University
Smart Materials and Structures | Year: 2010

A new composite magnetorheological elastomer (MRE) embedded with a copper coil was designed to induce a magnetic field inside and improve the field-dependent properties of the MRE. The composite MRE can avoid flux leakage, increase the utilization ratio of the magnetic field, and make magnetorheological equipment lightweight. A shearing stress-strain experiment for the composite MRE was carried out and the result showed that the composite MRE has a good magnetorheological effect. © 2010 IOP Publishing Ltd.


Chen L.,Key Laboratory for Optoelectronic Technology and Systems | Chen L.,Chongqing University | Li P.,Key Laboratory for Optoelectronic Technology and Systems | Li P.,Chongqing University | And 4 more authors.
IEEE Transactions on Magnetics | Year: 2011

This feature of rather large magnetoelectric (ME) coupling at the resonance enables the ME composites to possess great ME energy conversion ability. This paper proposes a new type of ME transducer fabricated from the ferromagnetic alloy FeNi-FACE, high-permeability FeCuNbSiB (Fe73.5Cu 1Nb3Si13.5B9) and piezoelectric PZT-8H to achieve the strong ME coupling. On one hand, the effective mechanical quality factor (Qm) of the transducer is significantly high because of the high quality factor values of FeNi-FACE, PZT-8H and FeCuNbSiB respectively. On the other hand, FeCuNbSiB acts as the dynamic driver to enhance the effective piezomagnetic coefficient d33 of the FeNi-FACE. A high ME voltage coefficient (MEVC) and a high ME power output can be obtained since the MEVC and power output at resonance strongly depend on the d33 and the Qm. The experimental results show that the strain coefficient of the FeNi-FACE/FeCuNbSiB laminate at resonance achieves 250 nm/A under H dc =23 Oe, which is 6.02 times as high as that for a single FeNi-FACE layer. The maximum MEVC at resonance (αr) achieves 4.65 V/Oe, which is 1.6 times larger than that of the previous Terfenol-D/PZT/Terfenol-D (MPM) composite transducer. The new transducer can obtain an output power of 103.7 μW under a resonant excitation Hac = 0.4 Oe, which is ∼16 times higher than that of the previous ultrasonic-horn-substrate composite transducer and decreases the size by nearly 75%. © 2011 IEEE.


Yang P.,Key Laboratory for Optoelectronic Technology and Systems | Yu M.,Key Laboratory for Optoelectronic Technology and Systems | Fu J.,Key Laboratory for Optoelectronic Technology and Systems | Liu S.,Key Laboratory for Optoelectronic Technology and Systems | And 2 more authors.
Polymer Composites | Year: 2015

As a kind of new MR material, Magnetorheological Gel (MRG) can be considered to be the intermediate system between the MR fluids (MRF) and MR elastomers (MRE). And damping performance plays a significant role in its application system (especially in the vibration and noise control). However, the damping mechanism and source of MRG have not been investigated comprehensively. In this study, several samples of MRGs with different iron particle contents (0, 20, 40, 60, and 80 wt%) were prepared. The nonmagnetic damping (without magnetic field) and magneto-induced damping (with several constant magnetic fields) of MRG were systematically studied by using an advanced commercial rheometer under oscillatory shear modes. The influence of time history, strain amplitude and frequency in the zero-field and several constant magnetic fields on the nonmagnetic damping and magneto-induced damping of MRG was also systematically studied. The experimental results show that, just the opposite to MRE, the loss factor of MRG decrease with the increase of carbonyl iron powder particles (CIP) content. The reasons are known through theoretical analysis combined with microstructure observation that the polyurethane molecular chain will become shorter with the increase of CIP content is a very important factor, and the formation and thickening of the chain structure of CIP is the reason for the loss factor of MRG decline with the magnetic field. © 2015 Society of Plastics Engineers.

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