Coupled Thin Film Hydrogenated Amorphous Silicon Microresonator Arrays

Mechanically coupled resonators can potentially improve the sensing capabilities of MEMS resonators. This work presents novel weakly and moderately coupled MEMS bridge resonators with up to four degrees-of-freedom (DOF), with thin-film hydrogenated amorphous silicon thin films as structural layers fabricated on glass substrates by surface micromachining at temperatures no greater than 175 degrees C. The electrostatically actuated coupled resonators exhibited flexural fundamental resonance frequencies near 1 MHz. Coupled resonance modes were simulated by Finite Element Method and characterized using optical and electrical sensing. Laser Doppler vibrometry was used to scan the coupled mode shapes and confirm resonance mode attribution. Coupled resonators with 4-DOF exhibited motional resistances similar to 25 times lower than single resonators (1-DOF) actuated with identical voltages. Common (in-phase) and independent (out-of-phase) actuation of the coupled resonators was implemented, resulting in distinct dynamic behaviors of the coupled array. The fabrication process presented in this work is easily scalable to higher degrees-of-freedom and to large-area substrates, which makes it a good fit for large-scale sensing applications. [2022-0161]

Automated summary

This study presents novel weakly and moderately coupled MEMS bridge resonators with up to four degrees-of-freedom (DOF) on glass substrates. These resonators have thin-film hydrogenated amorphous silicon as structural layers and are fabricated using surface micromachining at temperatures below 175°C. The coupled resonators exhibit flexural fundamental resonance frequencies near 1 MHz and show distinct dynamic behaviors depending on the actuation (common or independent) of the array. The fabrication process is easily scalable to higher DOFs and large-area substrates, making it suitable for large-scale sensing applications.