2237 Sensors and Materials, Vol. 36, No. 6 (2024) 2237–2248 MYU Tokyo S & M 3665 * Corresponding author: e-mail: nguyen.van.toan.c6@tohoku.ac.jp ** Corresponding author: e-mail: takahito.ono.d4@tohoku.ac.jp https://doi.org/10.18494/SAM5027 ISSN 0914-4935 © MYU K.K. https://myukk.org/ An Electromagnetically Driven Micromirror with a Large Stroke Chuan-Hui Ou, 1 Nguyen Van Toan, 1* and Takahito Ono 1,2** 1 Department of Mechanical Systems Engineering, Tohoku University, 6-6-01 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8579, Japan 2 Micro System Integration Center, Tohoku University, 519-1176 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-0845, Japan (Received February 21, 2024; accepted April 19, 2024) Keywords: electromagnetic force, micromirror, interferometer, microfabrication, large stroke In this research, a micromirror driven by electromagnetic force is designed and fabricated. The micromirror features a microfabricated L-shaped spring for large deflection and a bulk permanent magnet with a size of 1 × 1 × 1.5 mm 3 mounted on the micromirror for generating electromagnetic actuation force. The device has a footprint of approximately 10 × 10 mm 2 . The design of the micromirror is based on Castigliano’s theorem, theoretic spring constant evaluation, and finite element analysis, which are applied to estimate the deflection. The fabricated micromirror can be actuated at the resonance frequency in the atmosphere. The piston vibration at a fundamental frequency of 26.6 Hz is desirable for Michelson interferometers. An 830 µm stroke is achieved by applying 1 Vpp at the resonance frequency, and a 4.44° tilting angle is observed. Overall, the large stroke of the fabricated micromirror implies that the electromagnetic micromirror is promising for high-resolution interferometer applications. 1. Introduction Miniaturized interferometers have attracted the interest of many researchers for their potential to be intelligent systems-on-a-chip. (1) Miniaturized interferometers can be applied in various fields such as space research, environment monitoring, physical observation, and industrial safety analysis. (2–5) Compared with conventional interferometers, microfabricated interferometers are compact and cost-effective, which expands their application fields. There are various applications, for instance, Fourier transform infrared spectroscopy (FTIR) for identifying and quantifying chemical compounds and structures, (6–8) optical coherence tomography (OCT) for medical examination, (9,10) and hyperspectral imagers for measuring the spectral content of each pixel. (11,12) Interferometers generate interferograms by shifting the phase of light. Movable mirrors play an important role in controlling the phase of light in various interferometers. The stroke of a movable mirror directly affects the resolution of interferograms. The long stroke motion is the key factor in attaining a high performance. For gas sensing applications with FTIR, a resolution