Development of high-performance resonant accelerometers

Micro-Electro-Mechanical-System accelerometers have been integral in various applications for years due to their precision, versatility, and compact size. They have found relevance in sectors ranging from aerospace to inertial sensing, navigation systems, wearables, the Internet of Things (IoT), precision machinery sensing, seismometers, and gravimetry. Substantial research has been conducted in these areas. Among different transduction methods, resonant accelerometers are known for their high precision and dynamic range. However, a notable limitation is their sensitivity. The acceleration in these devices is converted into an axial force on a micro-resonator. Due to the inherent stiffness of these structures, there is a compromise in their sensitivity. To address this, techniques have been investigated to enhance the sensitivity, aiming to produce a high-performance accelerometer. We introduced "process-agnostic structures" - innovative modifications intended to heighten the sensitivity of microbeams. By altering the boundary conditions of these beams, moving from conventionally clamped beams to pinned beams or free beams, sensitivity has been substantially improved – up to a four-fold increase. Furthermore, these devices have a superior quality factor. A significant advantage of these modifications is their universal applicability. They are compatible with any fabrication process prevalent in the industry and academia, negating the need for material or interface electronics changes. Additionally, in our quest to amplify mechanical sensitivity, resonator beams with micro-lever structures have been combined. This integration was projected to enhance the sensitivity further. After simulations and fabrication of the experimental devices using Deep Reactive Ion Etching processes, a combination was found that could enhance sensitivity by approximately 30%. Our research, backed by simulations and experimental testing, validates our design approach. We have achieved substantial advancements in resonant accelerometers.