The key to making the affordable, small gyroscope is a nearly symmetrical mechanical resonator. "It looks like a Bundt pan crossed with a wine glass," say the researchers, made one centimeter wide. As with wine glasses, the duration of the ringing tone produced when the glass is struck depends on the quality of the glass — but instead of being an aesthetic feature, the ring is crucial to the gyroscope’s function.
The complete device uses electrodes placed around the glass resonator to push and pull on the glass, making it ring and keeping it going.
“Basically, the glass resonator vibrates in a certain pattern," says Sajal Singh, a doctoral student in electrical and computer engineering who helped develop the manufacturing process. "If you suddenly rotate it, the vibrating pattern wants to stay in its original orientation. So, by monitoring the vibration pattern it is possible to directly measure rotation rate and angle.”
The way that the vibrating motion moves through the glass reveals when, how fast, and by how much the gyroscope spins in space. To make their resonators as perfect as possible, the researchers start with a nearly perfect sheet of pure glass - known as fused-silica - about a quarter of a millimeter thick. They use a blowtorch to heat the glass and then mold it into a Bundt-like shape - known as a "birdbath" resonator since it also resembles an upside-down birdbath.
Then, a metallic coating is added to the shell and electrodes placed around it initiate and measure vibrations in the glass. The whole assembly is encased in a vacuum package, about the footprint size of a postage stamp and half a centimeter tall, which prevents air from quickly damping out the vibrations.
A paper - “0.00016 deg/vhr angle random walk (ARW) and 0.0014 deg/hr bias instability (BI) from a 5.2M-Q and 1-cm precision shell integrating (PSI) gyroscope”