Design,Fabrication And Test Of A Mems Electromagnetic Vibration Energy Harvester

With the rapid development of MEMS technology,more and more microelectronic devices are widely used in many areas of life.Many wireless sensor devices need continuous work,and how to power these devices for a long time is a key issue.Batteries are widely used to supply power,however,their life is limited.Moreover,it is difficult to implement regular battery replacement in harsh environments or embedded devices.Compared with the many shortcomings of batteries,energy harvesting technology can convert the energy in the environment into electrical energy,instead of traditional power supply methods for powering electronic devices.Compared with other energy sources,vibration is ubiquitous in life,so vibration energy has great research value.The core of the vibration energy harvester is to collect the mechanical energy of the surrounding environment and convert it into electrical energy.Since this technology does not require fuel consumption,it can theoretically solve the problem of limited life due to the difficulty of replacing the battery of microelectronics.It is very suitable for micro-power-consumption of electronic devices.Therefore,research on vibration energy harvesters is of great significance.Most of the traditional electromagnetic vibration energy harvesters are made by machining methods,and they are characterized by large size,high cost,and poor portability.The MEMS electromagnetic vibration energy harvester is small in size,can be mass-produced,and has good portability,which can well overcome the shortcomings of the traditional electromagnetic vibration energy harvester.This paper proposes a MEMS electromagnetic vibration energy harvester composed of a line/space magnet array and a planar micro meander copper coil,which has the advantages of portability and mass production.The structure is optimized with the help of finite element analysis,the main components of the energy harvester are processed and assembled using MEMS technology,and finally the output performance of the energy harvester is tested in the vibration test system.The main research contents of this paper are as follows:(1)Determine the structure of the electromagnetic vibration energy harvesterUse ANSYS and Maxwell software to design and optimize the structure of the device.The increase in the thickness of the spring and the increase in the width and spacing of the folded beam will increase the elastic coefficient of the spring.The reduction of the spacing and the increase of the size of the mass can reduce the natural frequency of the vibration pickup system.To divide the permanent magnet can increase the magnetic field of the permanent magnet within a certain range.The energy conversion system composed of the line/space magnet arrays and the planar meander copper coil has better output performance than the energy conversion system composed of the whole permanent magnet and the planar spiral coil.Finally,this paper obtains a reasonable structure of MEMS electromagnetic vibration energy harvester through simulation optimization method.(2)Determine the processing technology of the electromagnetic vibration energy harvester and make the energy harvesterEtching and electroplating were used to make the planar silicon-based copper coil,and cutting was used to make the line/space permanent magnet arrays,and laser processing was used to make the planar copper spring and the intermediate support layer.The basic process is integrated and innovated to form the processing method of the MEMS electromagnetic vibration energy harvester suitable for this article.Assemble the manufactured parts to obtain an energy harvester including a line/space permanent magnet array and a meander coil structure.(3)Test the performance of electromagnetic vibration energy harvesterThe actual measured value of the elastic coefficient of the planar copper spring is greater than the simulated value,because the simulated Young’s modulus of the copper material is smaller than the Young’s modulus of the copper material actually used to make the spring.In the results of the magnetic induction intensity measurement on the surface of the strip-shaped permanent magnet array,the magnetic induction intensity at the edge is less than the simulated value and the magnetic induction intensity curve is asymmetrical,because the cutting process of the tool will damage the permanent magnet.Under the condition of random vibration at 0.04 g~2/Hz,the maximum output voltage of the energy harvester is about 20 mV.In the range of 0-300 Hz,when the acceleration of the vibration source exceeds 1.3 g,the output voltage is stable at about6 mV.After simulating and optimizing the structure and formulating the process,the production of the MEMS electromagnetic vibration energy harvester is completed.The test shows that the device has a certain power generation capacity,which provides a solution for the power supply of wireless electronic devices that are difficult to replace the battery.It provides a basis for improving the output performance of the electromagnetic vibration energy harvester.