【作者】 杜小振；

【导师】 褚金奎；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2008， 博士

【摘要】 近年来,随着集成电路技术和微/纳机电系统（MEMS/NEMS）技术的不断提高,无线传感网络节点及便携式微电子产品应用越来越广泛。目前,微器件的电源主要是化学电池,但随着节点体积减小和使用数量迅速增加,更换大量的耗尽电池非常困难,研制长寿命的微型化电源技术已经成为亟待解决的关键技术问题。本文首先综合分析了微电源技术的研究进展,从能量的产生与转换、工作原理等方面比较了传统电源与新型电源的特点,提出研究环境振动驱动的微型发电装置。主要有三种能量转换形式可以实现环境振动能到电能的转换,即:压电转换、电磁转换和静电转换。其中,压电转换具有能量密度高、工作可靠、适应性强等突出优点。针对压电转换特点,本文主要研究环境振动驱动的微型压电发电系统的理论计算、优化分析、集成化制作工艺等关键技术,最后,对微型发电装置的能量输出性能做了测试分析。利用环境振动驱动的微型压电发电装置研究需要考虑电源的能量输出特性与环境振动的关系。因此,本文首先建立了压电发电系统从环境振动能到电能转换的理论模型,利用数值计算分析了系统的能量输出特性。分析结果表明在共振状态下获得输出能量较大,当系统的固有频率偏离环境振动频率时,输出电压、功率等将会快速的降低。另外,利用本文的理论模型分析了压电发电装置的结构尺寸参数和外部负载与输出电量的功率关系等。本文利用有限元模型中的压电耦合模块对微型硅基压电发电装置作了仿真分析,确定结构设计与输出电压的关系,进而设计硅基压电悬臂梁的加工尺寸,提高能量转换效率。仿真分析结果表明悬臂梁的长度、厚度和自由端质量块的大小对输出电压的影响最大,梁的宽度对输出电压的影响并不明显;悬臂梁尺寸在2mm×0.4mm×10μm范围的微型硅基压电发电装置输出电压达到0.02V左右。这些分析结果对结构设计与试验测试研究都提供了重要参考。本文针对硅基压电悬臂梁结构微型发电装置的微加工制作工艺进行了研究,解决了微加工过程中压电薄膜制备、电极图形化、悬臂梁释放等关键技术问题。首先,研究了PZT压电薄膜的制备工艺与过程,主要包括溶胶前驱体的配制、退火温度控制等。经反复的试验获得了稳定的前驱体溶胶,并最终确定PZT制备过程的阶梯退火工艺,在Pt/Ti/SiO₂/Si基底上制备了具有良好压电性能的PZT薄膜结构。其次,研究利用微加工工艺实现硅基PZT压电发电装置的集成化制作,分别利用光刻胶剥离和王水湿法腐蚀实现上下电极图形化,悬臂梁的释放结合了硅湿法腐蚀和离子刻蚀机（ICP）干法刻蚀技术,另外上电极保护层采用不定型PZT薄膜。以上研究保证了工艺的兼容性,体现在所有工艺步骤之间互不影响,采用的干、湿法刻蚀技术和薄膜图形化工艺等制作工艺与IC工艺和微加工工艺等兼容。本文确定的悬臂梁的制作工艺步骤简单,制作方便。最后,本文对设计制作的两种类型PZT压电悬臂梁微型压电发电装置的原型样机进行了性能测试分析。以金属弹性材料制作的微型压电电源测试为主,分析了系统转换的能量输出特性,其固有振动频率在100Hz左右共振时,系统输出电压达到10V以上,对纯电阻耗能元件的输出功率可以达到100μW左右,硅微型压电悬臂梁微型发电系统在1000Hz附近的振动驱动下输出电压可以达到0.015V左右。输出电能经整流与存储有望为微型传感器节点提供电能。更多还原

【Abstract】 In recent years, with the development of the integrated circuit and micro/nano electric-mechanical technology, the demand for wireless sensors nodes and portable electronics has been spreading speedily. The wireless devices are usually designed to run on batteries; however as the networks increase in number and the micro systems decrease in size, it is inconvenient to replace the exhausted batteries periodically. So the longtime micro power sources have been a pivotal issue in their diversified applications. To prioritize micro power options a comparison has been performed about the energy conversion theories of micro batteries. The micropower generator based on ambient vibration energy sources will be the most promising micro power sources and there are three conversion methods to achieve this type of energy, which are piezoelectric, electromagnetic and electrostatic conversion. As a micro power source the piezoelectric power generator is capable of the higher power output densities, reliable and adapts more fields. The specific scope of this thesis includes theory model and finite element analysis for micro piezoelectric power and developing a novel prototype fabrication process based on silicon films for integration. The experiment is carried out to show the batteries characters.The piezoelectric cantilever theory model is well known as a sensors and actuators, but which was used in a new scope of batteries to harvest ambient vibration has not been yet fully developed. In this thesis the theory analysis models were considered to calculate the output power and voltage from the micro cantilever piezoelectric batteries. And the calculation results showed that the output values appeared maximal values when the ambient vibration frequency approaches the natural frequency of micro power structures. As the forcing frequency deviated from the natural frequency the output power will decrease rapidly. The theory models also reflect the output values changing with dimensions of micro piezoelectric power.The relation of output voltage to micro piezoelectric cantilever based on silicon films is simulated by finite element method （FEM）. The analysis models were done using ANASYS because of its capability to work with coupled-field elements. The simulation results indicated that the voltages would increase as the piezoelectric cantilever length and proof mass at the free end increasing, and the thickness decreasing. The open circuit voltage is about 0.02V with dimension about 2mm×0.4mm×10μm. The simulation results can be useful for micro power generator design.The micro fabrication processes are investigated for the piezoelectric cantilever power generator and this work includes the preparation of the ferroelectric lead zirconate tianate （PZT） thin films, pattern the electrode and PZT films and the free end release of microcantilever. Firstly to deposit uniform PZT thin films on Pt/Ti/SiO₂/Si substrates by Sol-Gel method the precursor sol solution is pivotal and allows to gel at low temperature. A novel stepped annealing method is presented to control the crystalline state forming. The low electric plats pattern by wet etching with aqua regia. The top electrics do by lift-off technology and which are covered with amorphous PZT film to isolate from air. The wet and dry bulk micromachining techniques are adopted to release the micro silicon cantilever. These micro micromachining processes realize the compatibility and integration of micro piezoelectric batteries.The output power and voltage characters of micro prototype generators are surveyed. The test results indicate that the micro piezoelectric cantilever power generators based on metals can resonate with a frequency about 100Hz at the ambient vibration and produce approximately voltages ranging from 10V to 20V. The output power is about 100μW induced on the pure resistance. The output voltage is about 15mV from the micro piezoelectric cantilevers generator based on silicon film. The test results are consistent with the theory analysis. The research results indicate that a piezoelectric generator for ambient vibration energy harvesting is a promising long lifetime electric power source to meet the needs of wireless sensors nodes with micropower consumption.更多还原