Micro energy harvesting technology is to utility some effects to convert the energy around the enviroment into electrical energy.So it can supply the energy for the MEMS devices in the embedded system and wireless sensors networks.This paper discusses a piezoelectric micro energy harvesting device which is based MEMS technology.This device works in low frequency environment.When excited by the vibration,the device can convert the mechanical energy into electrical energy.But the direct output electrical energy of the energy harvesting device is AC voltage and usually can not be supplied to the devices directly.So AC-DC circuit is used to convert AC voltage into DC voltage and then it will be supplied to the MEMS devices.This paper gives the testing circuit of the micro energy harvesting device and analyzes the result.It demonstrates the feasibility of the micro energy harvesting in the low frequency enviroment.

Piezoelectric power generator made by microelectromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed MEMS power generators are featured with fixed/narrow operation frequency and power output in microwatt level, whereas, the frequency of ambient vibration is floating in some range, and power output is insufficient. In this paper, a power generator array based on thick-film piezoelectric cantilevers is investigated to improve frequency flexibility and power output. Piezoelectric cantilevers array has been designed and fabricated. The cantilevers array can be tuned to the frequency and expanded the excited frequency bandwidth in ambient low frequency vibration. Serial connection among cantilevers of the array is investigated. The prototype generator has a measured performance of 3.98 μW effective electrical power and 3.93 DC output voltage to resistance load. This device is promising to support networks of ultra-low-power, peer-to-peer, wireless nodes.

The configuration of the disc-type non-contact ultrasonic motor was analyzed in this paper.Natural frequency of the vibration mode was calculated by finite element method,and the results were coincident with the results of the vibration theory.Because vibrational amplitude was tightly correlated with operating of the non-contact Ultrasonic motor,the relevant factors were discussed,including the ratio of inner and outer radius,thickness and voltage of the stator.Such gives the theoretic base for the motor's design and optimization.

A piezoelectric-cantilever-type microvibration pickup sensor is presented.To design appropriate structure for concrete vibration conditions,the natural frequency and corresponding voltage signal output are calculated and analyzed by finite element method.MEMS technique is utilized to fabricate device prototypes and they are measured.The results indicate that the voltage outputs of the fabricated prototypes are over 200 mV under a low frequency harmonic excitation of 9.8 m/s2 acceleration.Due to the influence of the variance resulted from PZT film preparation and silicon wet etching,the testing results may be considered to be accordant with the simulation results,which lay valuable foundation for design and fabrication on high performance microvibration pickup sensors.

A MEMS-based energy harvesting device, micro piezoelectric power generator, is designed to convert ambient vibration energy to electrical power via piezoelectric effect. In this work, the generator structure of composite cantilever with nickel metal mass is devised. Micro-electronic-mechanical systems (MEMS) related techniques such as sol–gel, RIE dry etching, wet chemical etching, UV-LIGA are developed to fabricate the device and then its performance is measured on vibration testing setup. The investigation shows that the designed device is expected to resonantly operate in low-frequency environmental vibration through tailoring the structure dimension. Under the resonant operation with frequency of about 608Hz, a first prototype of the generator result in about 0.89V AC peak–peak voltage output to overcome germanium diode rectifier toward energy storage, and its power output is in microwatt level of 2.16μW.

The process of a Si-based piezoelectric microcantilever was introduced.Especially,the technique of the reactive ion etching of silicon was studied emphatically.During etching of silicon,it was analyzed that the etching rate,uniformity and selectivity can be effectively improved by adjusting technological parameters properly,such as gas flow,RF power,working pressure,etc.The results indicate that the etching rate of Si can reach 401 nm/min and the non-uniformity on a 3″ wafer is controlled at±3.85% when the flow of SF6 is 20 mL/min,RF power is 20 W and the work pressure is 8.00 Pa.The research lay a well foundation for the fabrication of piezoelectric microcantilevers or other microstructures with functional thin film.

Piezoelectric-cantilever micro vibration pickup sensor was realized using micro-electronic-mechanical systems (MEMS) technique such as sol-gel, RIE dry etching, wet chemical etching, UV-LIGA. The dimension of the vibration pickup is of cantilever length×width: 2 000 μm×600 μm, with silicon layer thickness 12 μm, PZT layer thickness 1.5 μm and the added Ni metal mass is of length×height: 600 μm×500 μm. The testing results show that the natural frequency of the structure is 610 Hz, which meet the low frequency application condition well, and the voltage output is about 562 mV under 1 gn resonant vibration drive.

Various high aspect ratio microstructures were prepared on the basis of UV-LIGA technique by using a new type of SU-8 photoresist. The influences of heat treatment and exposure on high aspect ratio microstructures are mainly discussed. The cracking and collapse of microstructures are favorably solved. Based on a series of contrast experiments, the SU-8 process is optimized and the highest aspect ratio of microstructures with 27:1 is successfully obtained.

设计了一种硅微悬臂梁结构,在低频环境中以压电厚膜进行信号转换、谐振.使用有限元分析软件ANSYS对结构建模,并进行模态和谐响应分析.模拟分析的结果表明:通过制备添加金属质量块及选择合理的尺寸范围,结构固有频率可在100～1500Hz之间;该结构在共振条件下将运动信号转换为电压信号输出时,电压可达0.4V以上,足以开启双锗二极管进行电路整流.

PZT thick films are prepared through sol-gel method and sensor cell structure of Si/SiO_2/Ti/Pt/PZT/Ti/Pt is formed.Based on optical lithography,the dry etching techniques for electrode and wet chemical etching techniques for PZT thick film were studied to realize the micro patterning of the sensor cell.Challenges such as etching Pt/Ti bottom electrode,morphology of PZT film and peeling of top electrode are solved,which laid solid foundations for the research and development of the high performance vibration pickup device.

The bi-layer micro gears have been fabricated by UV-LIGA technique using SU-8 photoresist. The max thickness of each layer can reach 450 μm. Fabrication of these bi-layer gears has been realized through three process schemes, namely separately electroforming, once-electro-forming on a seed layer and directly once-electroforming. The advantages and disadvantages of three process schemes are discussed respectively. Separately electroforming process is appropriated for the fabrication of various microstructure devices which mechanical demand is not high. Once-electroforming methods are used in cases where mechanical demand is high. The seed layer once-electroforming is appropriated for the fabrication of moulds of low aspect ratio microstructures, while the directly once-electroforming is appropriated to the high aspect ratio microstructure devices.

The configuration of the disc-type non-contact ultrasonic motor is given in this paper. The natural frequency and corresponding vibration mode are calculated and analyzed by finite element method. To verify the effectiveness of finite element model,measurements by a laser doppler vibrometer are made and good agreement between simulational and experimental results is shown. Because vibrational amplitude is tightly correlated with the acoustic radiation pressure of the non-contact motor, the relationship between the vibrational amplitude and applied voltage of the stator is discussed by harmonic analysis.The results show that the vibrational amplitude increases proportional to the applied voltage which served as the theoretical base for the motor's design and optimization. The revolution speed measured under the optimal B_(21) vibration mode is 1600 rpm.

Eddy current testing system of carburized materials was developed by using ANSYS software as second development platform. Finite element preprocessor, eddy current electromagnetic field calculation, the postprocessor and the visualization processor were integrated together in the software system, and good graphic user interface was also offered.

An analysis software is developed based on the theory of finite element calculation in an axis-symmetric eddy current electromagnetic field. Induction voltage values of the eddy current testing coil with different carburized depths are calculated. Results show that there exists a perfect corresponding relationship between the induction voltage and the carburized depth. The experimental results of the induction voltage values are well matched with the theoretical ones.

A finite-element equation related to test of case-depth using eddy current is deduced. Software is developed to compute this equation and perform post-processing and magnetic induction intensity image with different case-depths is gained. The results show that the distribution of magnetic field differs according to the variation of case-depths and the calculation results well agree with the experimental ones.

对通氨滴醇奥氏体氮碳共渗工艺进行了试验研究,分析了渗层的相组成、相的分布形态和氮浓度分布,对渗层的冲击韧度和耐磨性进行了试验研究.结果表明,渗层主要由化合物层和残留奥氏体层组成;化合物层主要由ε和γ′相组成;ε为柱状晶,γ′呈颗粒状分布于ε相中;残留奥氏体中存在丰富的孪晶、位错等亚结构;渗层具有较高的冲击韧度和较好的耐磨性能.

对5CrNiMo钢的渗硼工艺、渗硼层组织及渗硼后的性能进行了试验研究.结果表明,化合物层主要由Fe2B组成,另有少量含硼合金渗碳体;渗硼后材料耐磨性提高8倍以上,且具有一定冲击韧度;渗硼后进行高温淬火回火能显著提高冲击韧度.