Cooperative shape memory actuator systems for nanomechanics and nanophotonics

该提案代表了联合项目“纳米力学和纳米光子学合作形状记忆致动器系统”的更新。在第一个资助期间，我们证明了在室温以上通过焦耳加热的双向致动对于厚度低至220 nm的TiNiHf形状记忆合金（SMA）膜是可能的。然而，三晶型PMMA/TiNiHf/Si结构设想的压电致动只能通过耦合模拟研究到目前为止，揭示了需要厚的聚合物层，这在制造和热致动中引入了问题。因此，在这个项目扩展中，我们将（1）通过引入和研究平面内和平面外的MEMS驱动的新概念来缓解这些问题，（2）探索和数值描述尺度缩小和尺寸效应，以及（3）分别为Si微机械和Si纳米光子学应用开发合作多稳态平面内和平面外微致动器。双稳态SMA微致动将基于耦合预应变SMA桥微致动器。它们的功能将取决于来自热处理的应力和来自薄膜生长过程的内在应力。计算辅助迭代设计过程将有助于确定具有高精度和小型化潜力的鲁棒和节能的致动器系统布局（S。Wulfinghoff）。精确控制材料性能，包括应力工程（A. Ludwig）将与最先进的微机械加工相结合，用于SMA/Si微致动器与Si微机械和/或纳米光子波导结构的共同集成（M。科尔）。基于多稳态微致动器系统的实验和仿真相结合的评估，不希望的交叉灵敏度将被最小化，协同效应将得到增强。

This proposal represents the renewal of the joint project “Cooperative shape memory actuator systems for nanomechanics and nanophotonics”. During the first funding period we demonstrated that bi-directional actuation by Joule heating above room temperature is possible for TiNiHf shape memory alloy (SMA) films with thicknesses down to 220 nm. However, trimorph PMMA/TiNiHf/Si structures envisioned for bistable actuation could only be investigated by coupled simulations so far revealing the need for thick polymer layers, which introduces issues in manufacturing and in thermal actuation. Therefore, in this project extension, we will (1) mitigate these issues by introducing and investigating novel concepts for bistable SMA actuation in-plane and out-of-plane, (2) explore and numerically describe downscaling and size effects, and (3) develop cooperative multistable in-plane and out-of-plane microactuators for Si micromechanics and Si nanophotonics applications, respectively. Bistable SMA microactuation will be based on coupled pre-strained SMA bridge microactuators. Their functionality will depend on the stress from thermal treatment and intrinsic stress from the thin film growth process. A computationally-aided iterative design process will help to identify robust and energy-efficient actuator system layouts with high precision and downsizing potential (S. Wulfinghoff). Accurately controlled material properties, including stress engineering (A. Ludwig) will be combined with state-of-the-art micromachining for the co-integration of SMA/Si microactuators with Si micromechanical and/or nanophotonic waveguide structures (M. Kohl). Based on a combined experimental and simulation-based assessment of the multistable microactuator systems, undesired cross-sensitivities will be minimized and synergies will be enhanced.