光热微驱动机构动态响应特性的理论与实验研究

Theoretical and experimental study on dynamic properties of optothermal microactuator

理论和实验研究了脉冲激光照射下光热微驱动机构的动态响应特性,建立了微膨胀臂的光热温升及光热膨胀的动态模型,导出了动态光热膨胀伸长量及振幅的计算公式,并通过Matlab仿真得到它们与激光脉冲频率之间的理论关系曲线。设计与微加工制作了一种总长为700μm的非对称型光热微驱动机构(A-OTMA),在功率为2 mW、频率为2~18Hz可调的脉冲激光照射控制下开展了动态光热驱动实验。采用显微视频成像系统及运动测量软件,对A-OTMA光热微驱动过程进行了实时监测和测量。实验结果表明,A-OTMA能够以与激光脉冲相同的频率实现周期性偏转运动,光热偏转量及振幅随激光脉冲频率的增大而减小,其变化趋势与理论曲线吻合,获得的最大偏转量振幅为14.9μm(2 Hz时),最大响应频率至少达到18Hz。本文的动态响应特性的理论和实验研究,为OTMA在微光机电系统(MOEMS)及微纳米技术领域的实际应用提供了技术基础。

The dynamic properties of optothermal microactuator （OTMA） are theroretically and experimentally reported under pulsed laser irradiation.A dynamic model for describing optothermal temperature rise a nd optothermal expansion of the expansion arm is established.The formulas of dynam ic expansion and its amplitude are also derived,based on which the relationships among the expansion,expansio n amplitude and the laser pulse frequency are obtained through Matlab simulations.An asymmetric optothermal mic roactuator （A-OTMA） with length of 700μm is designed and microfabricated.Expe riments are carried out under pulsed laser with power of 2mW and frequency of 2-18Hz.The dynamic actuating of the A-OTMA is monitored by microscopic imaging system and is further analyzed using motion analysis software.The experimental results show t hat the A-OTMA can periodically deflect with the same frequency of laser pulse,and both of the max imum deflection and deflection amplitude decrease as the frequency increases,matching with the trends of theor etical curves quite well.It is also proved that the A-OTMA is capable of acquiring maximum deflection amplitude of 14.9μm （at 2Hz） and maximum response frequency up to 18Hz.This work can provide technical found ation for practical applications of optothermal microactuator in the fields of micro opto-electro-mechanical sy stem （MOEMS） and micro/nano-technology.