Research On MEMS-based Electrostatic Vibration Energy Micro-harvester

With recent development in microelectronics technology,research of wireless sensor networks,embedded sensors,implanted sensors has been done on a further level,the related electronic devices gradually developing towards miniaturization,integration and long life.While ultra low power circuit design technology continues to improve,how to power these micro devices effectively and continuously is becoming a key question to a further application research.Energy harvesting technology can transform the wide kinetic energy available in working environment into electrical energy to power these electronic devices,which is featured with long life,no need to replace regularly,applicable to rough working environment,and it’s easy to realize miniaturization and integration,combined with MEMS fabrication technology.This dissertation,based on MEMS fabrication criterion,focuses on electrostatic vibration energy micro-harvester,two different energy harvesters with distinctive characteristic are designed:planar two-dimensional vibration energy harvester;planar nonlinear wideband vibration energy harvester.The main contents and conclusions are as below:The first chapter discusses development status of energy harvesting technology,introduces the application and development of the typical mechanical vibration energy harvesting technology,their advantages and disadvantages are analyzed contrastively,on this basis,research content and framework of the dissertation are proposed.The second chapter analyzes electrostatic energy harvesting transformation mechanism,establishes the energy harvester vibration model,analyzes the frequency characteristics of forced vibration,introduces the MEMS micro processing technology and design rules.The third chapter designs a new planar two-dimensional vibration energy harvester,three different varying capacitance structures are analyzed contrastively,the influence factors of key component folded spring’s rigidity in three directions are analyzed through mechanics theory,explores the influence of spring geometric parameters on energy harvester’s first-order natural frequency,first-order modal vibration type and the difference in frequency between first-order natural frequency and second-order natural frequency using finite element calculation method,and optimizes the geometric parameters.The fourth chapter designs a new planar nonlinear wideband vibration energy harvester,targeting on the elastic potential of the nonlinear spring,introducing dimensionless parameter ξ,analyzes the relation between ξ and the corresponding wideband ability,optimizes the geometric parameters by characteristics of nonlinear spring force curve related to ξ,and modal analysis of the structure is done.The fifth chapter transforms mechanical system into equivalent circuit system,simulates the output power of planar nonlinear wideband vibration energy harvester using the equivalent circuit,analyzes the influence of load RL,bias voltage Vb,acceleration,driving frequency on the output power,compares the results with the corresponding linear system,verifies the wideband characteristic of nonlinear energy harvester.The sixth chapter reviews the full text,summarizes the main contents of this dissertation,and discusses further research to do.