This project explores a technology for implementation of a 6-axis micro inertial measurement unit (μIMU) on a single substrate. All inertial sensors are fabricated in parallel on a single silicon substrate, mechanically and electrically interfaced through flexible integrated thin-film polyimide hinges. When folded into a 3-D structure (i.e. a cube or a pyramid) the unit forms a single-chip 6-axis system. Connections for all sensors terminate on the bottom of the folded structure, allowing for surface-mount packaging of the device. Structures can be mounted either directly to a PCB, or to an adapter plate allowing for connection to a DIP package.
One of the main challenges of developing a chip-level IMU is combining multiple high-performance sensors on a single die capable of detecting motion along independent directions with minimal cross-axis sensitivity. This challenge is minimized by using the folded MEMS approach consisting of a 3-D SOI backbone suitable for high-aspect ratio sensor fabrication. Assembly is done on the wafer level and the panels are rigidly bonded together, forming a compact rigid 6-axis system of sensors. Accelerometers and gyroscopes are fabricated in parallel with the folded structure on the same substrate, and are electrically and mechanically interfaced through flexible polyimide hinges and interlocking silicon latches. Due to the advantages of high aspect ratio SOI-based sensor fabrication, high-performance single axis sensors with low cross-axis sensitivity can be employed. Additionally, a clock, integrated circuitry, and power source can be included to create a highly compact standalone IMU.
