Polymeric magnetic microactuator with efficient permalloy loop design

In the study, two types of polyimide (PI) magnetic microactuator with different geometries were designed, fabricated and tested. Mathematic model is created by ANSYS software to design the two microactuators, respectively. The magnetic field generated by the planar coil with permalloy circuit loop design was simulated by ANSYS software. The simulation result shows that the magnetic force can be up to 34.69 mN. Fabrication of the electromagnetic microactuator combines with 10 m thick Ni/Fe (80/20) permalloy circuit loop deposition, 10 m thick permalloy plate with 800 × 800 m in area on PI diaphragm, high aspect ratio electroplating of copper planar coil with 10 m in thickness, bulk micromachining, and excimer laser ablation. They were fabricated by a novel concept avoiding the etching selectivity and residual stress problems during wafer etching. First, PI diaphragm with micro-electroplated Ni/Fe permalloy was released by anisotropic wet etching, followed by mask projection of 248 nm excimer laser ablation. The new concept of excimer laser ablation process demonstrates that microstructure can be post-ablated after bulk micromachining. By applying a current through planar coil, the PI diaphragm will be actuated. ANSYS software was used to predict the deflection angle of the two types of microactuators. The preliminary theoretical simulation shows a good agreement with experimental result.The authors would like to thank Dr. Tung-Chuan Wu and Mr. M.-C. Chou at MIRL of ITRI in Taiwan for their guidances, and National Science Council (NSC) for their financial supports to the project (granted number: NSC92-2622-E110-009-CC3 and NSC92-2212-E110-029).