講演情報
[17a-B1-6]Visualization of strain distribution in MEMS resonators using stroboscopic differential interference contrast microscopy
〇Qian Liu1, Mirai Iimori1, Ya Zhang1 (1.Inst. of Eng., Tokyo Univ. of Agri. &Techno.)
キーワード：
MEMS、DIC microscopy、surface strain
MEMS resonators are promising for sensing applications owing to their intrinsic high sensitivities. In MEMS devices, piezoelectric or piezoresistive transducers are crucial for converting the mechanical vibrations into electrical signals. Since the output signal is in proportional to the surface strain, it is highly desirable to preciously characterize the surface strain distribution in MEMS devices. Currently, numerical methods such as Finite Element Method are commonly used to analyze the strain distribution in MEMS devices. However, owing to the small size of MEMS devices, experimental analysis of strain distribution remains challenging.
In this work, we propose a novel surface strain analysis method for MEMS resonators using stroboscopic differential interference contrast (DIC) microscopy. The stroboscopic DIC microscope visualizes the mechanical vibrations of MEMS devices through the interference of two light beams reflected from the sample surface with a small lateral shift. With the DIC images, we can obtain the differential surface deflection of MEMS resonators caused by the vibration motions. By further differentiating the result, we can obtain the deflection induced strain () distribution of MEMS resonators.
Here, we have performed the strain measurement for a GaAs doubly clamped MEMS beam resonator. The MEMS resonator is driven in its first bending mode, with a resonance frequency of ~695 kHz. The measured surface strain is distributed not only on the MEMS beam but also on the over etching part, indicating that the over etching effectively extends the vibration area, which must be considered in designing the transducers. The experimental result shows reasonable agreement with the numerical result, demonstrating the effectiveness of the stroboscopic DIC method for analyzing the surface strain distributions of MEMS devices.
In this work, we propose a novel surface strain analysis method for MEMS resonators using stroboscopic differential interference contrast (DIC) microscopy. The stroboscopic DIC microscope visualizes the mechanical vibrations of MEMS devices through the interference of two light beams reflected from the sample surface with a small lateral shift. With the DIC images, we can obtain the differential surface deflection of MEMS resonators caused by the vibration motions. By further differentiating the result, we can obtain the deflection induced strain () distribution of MEMS resonators.
Here, we have performed the strain measurement for a GaAs doubly clamped MEMS beam resonator. The MEMS resonator is driven in its first bending mode, with a resonance frequency of ~695 kHz. The measured surface strain is distributed not only on the MEMS beam but also on the over etching part, indicating that the over etching effectively extends the vibration area, which must be considered in designing the transducers. The experimental result shows reasonable agreement with the numerical result, demonstrating the effectiveness of the stroboscopic DIC method for analyzing the surface strain distributions of MEMS devices.
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