UCI researchers developed a sturdy architecture and straightforward fabrication procedure for the core sensing element in microscale gyroscopes for timing and inertial navigation applications.
·The structure can be instrumented to operate as a resonator, gyroscope, or other vibratory sensor.
·The robust nature of this structure yields advantages for precision operation in harsh environments.
·Inexpensive fused quartz composition
·Dual-shell design with fixed anchor reduces spurious tilt/out-of-plane modes of vibration from environment.
·Single fabrication step eliminates need for post-fabrication alignment and bonding of cap shell to device shell.
·The surface of the outer shell can be coated with a low emissivity material for low power ovenization as well as radiation protection.
A gyroscope measures angular velocity, or the rate of change of the sensor's orientation. Gyroscopes are used to measure and maintain rotational motion, such as, aeronautics, military, etc…, applications. These small gyroscopic components are known as Micro-Electro-Mechanical Systems (MEMS) gyroscopes which have low production cost to produce and low power consumption.
The shock impact reliability of MEMS gyroscopes is an area of concern when used in harsh dynamic environments having high-spin and high-g shock events, for instance in vehicle crash testing, human impact studies, and aerospace and ballistics measurements. The mechanical stresses induced by these harsh dynamic environments may lead to microcracks and fracture of the sensor.
UCI researchers designed a MEMS gyroscope having a new architecture which has a protective shield as well as a fixed anchor for the core sensing element for timing and inertial navigation applications.This MEMS gyroscope design is known as a hemispherical resonator gyroscope (HRG).The HRG works by sensing the change in phase of vibration of a cup-shaped resonator. Incorporation of a shell structure to the sensing element of the HRG provides structural symmetry, rigidity, and low energy losses, while accounting for uniform thermal distribution and reduced thermal gradients. This architecture is novel by introduction of a unique shell structure of the resonator. To support the manufacturing of the HRG, the researchers devised a unique fabrication process with a single glassblowing step. This novel shell structure with a fixed anchor will improve structural rigidity and high-g shock survivability in MEMS gyroscopes, and will enable operation through shock and external vibrations from harsh dynamic environments.
The researchers have developed the fabrication process using triple wafer alignment and bonding using plasma bonding, and high-temperature glassblowing. They demonstrated the first operating prototype and investigated trade-offs for design of novel shell resonators for shock survivability and operation through shock. The next steps will be to demonstrate the novel shell structure on electrode assembly and test gyroscope operation of the dual-shell resonator.