Microelectromechanical systems (MEMS) inertial units: Multi-axis resonant design using side wall grown AlN piezoelectric transducers

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master_Prieto_Lopez_Jacobo_Andres_2025.pdf (4.25 MB)

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School of Electrical Engineering | Master's thesis
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Date

2025-07-28

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Smart Systems Integrated Solutions

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Joint International Master in Smart Systems Integrated Solutions

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en

Pages

79

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Abstract

The demand for high-performance, miniaturized inertial measurement units (IMUs) has driven research beyond the limitations of conventional planar, capacitive-based Micro-Electro-Mechanical Systems (MEMS). This thesis investigates a novel transduction architecture for MEMS gyroscopes, centered on the integration of piezoelectric Aluminium Nitride (AlN) thin films onto both the top and vertical sidewall surfaces of resonant structures. The potential of this three-dimensional (3D) piezoelectric approach was evaluated through Finite Element Modelling (FEM) of two distinct gyroscope architectures: a single-axis Lissajous Frequency-Modulated (LFM) device and a multi-axis Amplitude-Modulated (AM) device. The results validate that sidewall-deposited AlN films provide a highly efficient mechanism for in-plane actuation and sensing, with the LFM gyroscope achieving a competitive scale factor of 0.84 Hz/Hz at a low 3V drive. The analysis of the AM gyroscope confirmed the feasibility of combining top and sidewall films to create a monolithic, three-axis sensor capable of supporting four mechanically orthogonal resonant modes. This work reveals a fundamental trade-off between the high efficiency of the novel transducer and the architectural complexity of multi-axis, modematched designs, which tempers single-axis performance. The primary contribution is the establishment of the 3D piezoelectric suspension spring as a versatile and efficient design primitive, and the findings suggest that future work on multi-axis Frequency-Modulated (FM) gyroscopes represents a promising pathway to combine the environmental robustness of FM operation with the multi-axis capabilities of the 3D transducer, enabling a new class of high-performance, fully integrated inertial sensors.

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Supervisor

Paulasto-Kröckel, Mervi

Thesis advisor

Ross, Glenn
Gabrelian, Artem

Keywords

gyroscope, piezoelectric, aluminium nitride (AlN), multi-axis sensing, side-wall deposition, Finite Element Modelling (FEM), Amplitude Modulation (AM)

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https://urn.fi/URN:NBN:fi:aalto-202508196319

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[dipl] Sähkötekniikan korkeakoulu / ELEC