Papers by Author: Zhi Yu Wen

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Authors: Xing Qiang Zhao, Zhi Yu Wen, Li Cheng Deng, Guo Xi Luo, Zheng Guo Shang, Dong Ling Li
Abstract: A micro piezoelectric cantilever beam array is designed for vibration energy harvesting. A single degree of freedom analytical model is developed to predict the properties of the device and is verified by finite element method. The piezoelectric material Aluminum Nitride was chosen for the compatibility with the CMOS process. The devices consisting of 5 piezoelectric cantilever beams and one proof mass were fabricated using micromachining technology. The resonance frequency, voltage and power were tested at excitation acceleration of 5.0 g. The maximum output power of the device is 9.13 μW at the resonance frequency of 1315 Hz when piezoelectric beams are connected in parallel.
Authors: Xing Qiang Zhao, Zhi Yu Wen, Zhi Gang Du
Abstract: A novel miniaturized piezoelectric wind flutter generator is proposed which consisted of a flexible beam and a PZT cantilever. The working principle is based on flexible beam flutter, which can amplify the PZT cantilever vibration. A prototype was tested in a wind tunnel. It is found that there are three behavior states with wind speed increasing, and flutter behavior takes place when wind speed varies between the critical wind speed Uc1 and Uc2, an empirical formula was obtained about the critical speed Uc1. The open circuit voltage and power were measured. The device can generate 794μW output power with 30kΩ resistor in a wind of speed 20m/s, power density is 139μW/cm3.
Authors: Hai Tao Liu, Zhi Yu Wen, Zheng Guo Shang, Li Chen
Abstract: The finite element method to obtain the stiffness of MEMS (Micro-Electro-Mechanical Systems) accelerometer is difficult to give an exact expression, so a new method to analyze the stiffness of MEMS accelerometer was purposed. Both Mechanics and electricity analysis were used to calculate the stiffness of vacuum microelectronic accelerometer developed in our laboratory, and the control and detection circuits were design according to the result. Finally, the sensitivity, linearity and other performance were measured through the static gravitational field experiments; the least squares curve fitting correlation coefficient 0.9999 and linear 0.9%. The result shows that this method to analyze the stiffness of the stiffness of vacuum microelectronics accelerometer is correct and feasible, and this method can also be applied to other MEMS accelerometer with symmetrical structure and electrostatic force balance mode.
Authors: Biao Luo, Zhi Yu Wen, Hai Tao Liu, Li Chen, Rong Rong Qian
Abstract: In order to realize more compact and in particular cost-effective spectrometers MOEMS technology offers attractive possibilities. Based Littrow spectrometer structure for the near-IR, a micro mirror grating spectrometer has been designed and developed. The ZEMAX was used for designed this structure. The resolution of this design is 10nm, the spectral range from 900nm to 1400nm. A scanning micro mirror is the key element of this IR spectrometer set-up. This micro mirror is driven by electromagnetic force. Before fix the micro mirror, it was calibrated. Meanwhile, for reducing the cost of this system, the silicon silt was designed and fabricated. For resolution testing of this spectral system, we used one light correction filters finished this experiment. The test result has shown the resolution of this spectrometer is16.8nm. Finally, the relation between the spectral line scanning characteristic and wavelength spectral resolution was discussed.
Authors: Rong Rong Qian, Zhi Yu Wen, Li Chen
Abstract: A novel piezoelectrically actuated scanning micromirror integrated with angle sensors is presented. The mirror with large size of 3×3mm2 locates in the center of the device, and piezoelectric actuators are symmetrically placed on both sides of the mirror. They are connected through torsion bars in which piezoelectric angle sensors are integrated. In order to obtain large deflection angle at a low operation voltage, the new actuator consisting of several parallel piezoelectric cantilevers is adopted. The machematical models of the mirror and piezoelectric actuator are given, and the piezoelectric angle sensors are designed to obtain high sensitivities. The simulation results indicate that the maximum mechanical deflection angle of the micromirror is 12.4° at an operation voltage of 25V, and the maximum output voltage of the angle sensor is 164.3mV. The resonant frequency associated with the torsional mode is 960Hz. The sensitivity of the angle sensor is 13.3mV/° without amplifying. The Scanning miromirror is suitable for optical scanning systems such as the microscope, the micro-spectrometer, the medical imaging, the barcode reader and so on.
Authors: Hai Yang Liao, Peng Tian, Yu Du, Zhi Yu Wen
Abstract: Water quality monitoring plays an important role in contamination control and environment protection. This paper describes an on-line multiparametric water quality monitoring system based on visible spectrophotometry, which combines embedded technology with GPRS telecommunication technology. This system can realize online wireless monitoring to concentrations of chromium (Cr), plumbum (Pb), A surfactant (AS), chemical oxygen demand (COD), ammonia nitrogen (AN), total phosphorus (TP) and total phenol (TPh) in real time. The mechanical structure, hardware circuit and software design of the system are completed. The absorption spectrums of pure water and MB-SDS complex have been measured. Preliminary experiments using a model machine show that each mechanism of the system runs well. Moreover, the monitor possesses many advantages, such as high degree of automation, high reliability, high efficiency, compact structure, small size, and so on.
Authors: Zheng Guo Shang, Zhi Yu Wen, Dong Ling Li, Sheng Qiang Wang
Abstract: It is known that the wet chemical etching of silicon in alkaline solution has attracted wide attention due to its advantages such as lower cost, simpler setup, higher rate, smoother surface at micro level, higher degree of anisotropy, and lower pollution. In this paper, the key processes of fabricating vacuum microelectronic accelerometer and slits are presented. The cone curvature radius of the silicon tip arrays less than 30nm was fabricated with wet anisotropic etching of silicon in 33wt. % KOH solution at 70°C added potassium iodine (KI) and Iodine (I2) as additive and the cone aspect ratio was about 0.7. Smooth surface after etching in 33wt. %KOH solution added isopropyl alcohol (IPA) at 80°C was obtained and lateral etching was less than 5um after etching several hours for etching depth over 400um. Scalar slits with bottom width 25um and depth 500um were attained. A constant etch rate lead to precise and reproducible production. The test result reveals that the process to a specific occasion can reach practical requirements.
Authors: Yi Ming Lei, Zhi Yu Wen, Li Chen
Abstract: This paper presents two electromagnetic vibration energy harvesters based on micro-electro-mechanical (MEMS) technology. Two prototypes with different vibration structures were designed and fabricated. The energy harvester includes a permanent magnet attached on vibration structure (resonator) made by Si and a fixed wire-wound coil, with the total volume of 0.9 cm3. Two energy harvesters with different resonator are tested and compared. Experiments show that: in the same acceleration and a load resistance, the resonant frequency of prototype B is approximately 95% of prototype A; The peak-peak voltage and the maximum power of prototype B is 1.6 times and 2.7 times of prototype A respectively. The test results was analyzed simply and it indicated that the electromagnetic energy harvesting with the spring B has better performance; also proved that the potential ability of the non-linear spring could extend the frequency bandwidth and improve output voltage.
Authors: Yu Liu, Zhi Yu Wen, Li Chen, Hong Yun Yang
Abstract: This paper presents a capacitive biaxial microaccelerometer with a single proof mass. The theoretical analysis results are confirmed by finite element analysis. The experimental results indicate the biaxial accelerometer with uniform axial sensitivities, good linearity and high cross-axis sensitivity immunity to the z-axis input.
Authors: Dong Ling Li, Zhi Yu Wen, Zheng Guo Shang, Sheng Qiang Wang
Abstract: This paper presents a simple but reliable fabrication process for microfluidic devices on glass substrate using wet etching technology. Instead of using expensive Pyrex glasses as substrates and depositing expensive metal or polysilicon/amorphous silicon as etch masks in conventional method, glass slide is used as substrate and a single-layer negative photoresist RFJ-220 is used as the etching mask. The etch rates, generation of defects, undercut ratio and surface roughness are studied. In order to achieve high etching depth and smooth surface, buffered oxide etching with hydrochloric acid as additive is proposed. By proper cleaning and long-time hard baking, the undercut ratio can approach to 1. An 110μm depth microchannel with smooth surface is achieved. This fabrication process leads to a considerable reduction of process steps, fabrication time and material consumption. With this technique, we successfully fabricated a microfluidic device, which is used in the capture of hepatoma cells HepG2.
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