Design, Fabrication and Testing of Miniaturised Wireless Inertial Measurement Units (IMU)

This paper will describe the design, fabrication, operation, and test results of a miniature wireless inertial measurement unit (WIMU) with a form factor of 10 mm. Many types of Inertial Measurement Units(IMU) have been designed and manufactured by prominent companies such as Crossbow, Xsens, O NAVI and Honeywell, among many others. American GNC Corporation currently claims to have the world´s smallest IMU[1]. Most of these IMUs are aimed at aerospace and other types of navigation, which is why miniaturisation has not been a priority. However, with the onset and development of MEMS technology, novel applications have been found for those MEMS sensors employed in an IMU. Head mounted displays, Segways and mobile phones are among the new products taking advantage of miniaturised MEMS inertial sensors. The current WIMU development is a step along the roadmap of the AES team at Tyndall National Institute towards miniaturisation and works from the current standard, the 25 mm platform [2]. A 25 mm stacked SMT IMU has been successfully developed and tested [3,4]. The goal now is to develop an even smaller version of this IMU by using advanced technology such as flexible substrates and flip-chip technique. These miniaturised IMU´s are required for wearable and medical applications where size and weight are priorities. Our WIMU uses bare-die versions of off-the-shelf MEMS sensors. The Inertial Measurement Unit itself is designed to give full six degrees of freedom with 3-axis for each of the sensors-accelerometers, gyroscopes and magnetometers.