TiNi/Si复合膜微驱动器原理及结构参数优化

Actuation Mechanism and Structural Optimization of

应用有限元方法对TiNi/Si复合膜微驱动器的结构设计进行了分析。因TiNi和Si之间的热膨胀系数差别很大 ,溅射在Si( 1 0 0 )衬底上的TiNi膜 ,当从晶化的高温降下来时会积聚很大的热应力。这种微驱动器 ,就是利用了TiNi的形状记忆效应而引起的这些应力的释放与恢复从而引起复合膜的振动。图形化TiNi薄膜制成加热电阻条作为自加热电阻 ,可降低功耗、提高响应速度、简化结构。但作为驱动单元的一部分 ,其图形化的结构参数对复合膜的挠度有很大的影响。通过结构参数优化 ,可使复合膜的中心挠度值达到最大 ,从而提高驱动器的性能。

A novel design of TiNi/Si composite membrane microactuator is studied with finite element methods(FEM). The actuation mechanism is due to the relaxa tion and recovery of tensile stresses by reversible phase transformations in near-equiatomic titanium-nickel(TiNi) thin films sputtered onto(100)-silicon(Si) during cyclic thermal excursions between M_fand A_f, which arise from the large difference in expansion coefficients between TiNi and Si. Many advantages are attributable to the patterned TiNi strips, including the decrease of power, the increase of response frequency and the simplification of the structure. However, as a structural part of the microactuator, its structural parameters have important effect on maximum central deflection and therefore the effective change of the volume. If the structural parameters are optimized, the characteristics of the microactuator can be improved dramatically.