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A novel design of a microelectromechanical systems (MEMS) control moment gyroscope (MCMG) was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor and gimbal, the coupling between which is based on the Coriolis effect and will cause a torque output in the direction perpendicular to the two vibrations. The angular rotor vibration was excited by the in-plane electrostatic rotary comb actuators, while the angular gimbal vibration was driven by an out-of-plane electrostatic parallel plate actuator. A possible process flow to fabricate the structure was proposed and discussed step by step. Furthermore, an array configuration using four MCMGs as an effective element, in which the torque was generated with a phase difference of 90 degrees between every two MCMGs, was proposed to smooth the inherent fluctuation of the torque output for a vibrational MCMG. The parasitic torque was cancelled by two opposite MCMGs with a phase difference of 180 degrees. The designed MCMG was about 1.1 cm × 1.1 cm × 0.04 cm in size and 0.1 g in weight. The simulation results showed that the maximum torque output of a MCMG, the resonant frequency of which was approximately 1,000 Hz, was about 2.5 × 10-8 N∙m. The element with four MCMGs could generate a torque of 5 × 10-8 N∙m. The torque output could reach a magnitude of 10-6 N∙m when the frequency was improved from 1,000 Hz to 10,000 Hz. Using arrays of 4 × 4 effective elements on a 1 kg spacecraft with a standard form factor of 10 cm × 10 cm × 10 cm, a 10 degrees attitude change could be achieved in 26.96s.

In this report, an improved in-plane electret energy harvester with gap-closing comb drives has been developed with a single-mask SOI process. By using 150 µm-thick device layer for increasing the seismic mass and 15 µm-thick buried oxide layer for reducing the parasitic capacitance, up to 5.3 µW output power has been obtained at 503 Hz, which is equivalent of five times higher power output than our previous prototype. In addition, the power output reaches as high as 45% of the Velocity-Damped Resonance Generator (VDRG) limit.

A novel in-plane MEMS electret energy harvester with combined electrodes of overlapping-area-change and gap-closing converters is proposed for large output power both at low and high vibration accelerations. An early prototype has been successfully micro-fabricated with the single layer silicon-on-insulator process. Soft X-ray charging is employed to establish uniform surface potential around 60 V on vertical electrets on the sidewall of the comb fingers. Up to 1.6 μW output power has been obtained, which corresponds to the effectiveness as high as 57%.

A novel MEMS electret vibration energy harvester sealed in a package before charging is developed, which should improve the package reliability and long-term stability of the charges. With an early prototype in package, vertical electret on the comb drives has been successfully charged with soft X-ray photoionization, and up to 3.58 μW has been obtained at 570 Hz and 2.2 g oscillation, which corresponds to the effectiveness as high as 42%.

A novel in-plane MEMS electret energy harvester with combined electrodes of overlapping-area-change and gap-closing types is proposed for large output power both at low and high vibration accelerations. An early prototype has been successfully micro-fabricated with the single layer silicon-on-insulator process. Soft-X-ray charging is employed to establish uniform surface potential around 60 V on vertical electrets on the sidewall of the comb fingers. Up to 1.19 μW output power has been obtained at 552 Hz and 2.15 g acceleration oscillations, which corresponds to the effectiveness as high as 27.2%.

A reduced micromachined inertial measurement unit (MIMU) was fabricated by a proposed two-step release silicon-on-insulator (SOI) process to meet the requirements of land vehicle navigation. The release process consists of two steps, that is, dry release using notching effect and wet release using hydrogen fluoride (HF) solution. By applying the presented layout design rules, most of the area of the device was released in the dry-etching process, but boundaries of the proof mass and the suspension beams were not released until the wet etching. Through such a process configuration, a smooth surface was obtained under some thickness-senstive structures such as suspension beams and a rough surface under some thickness-non-sensitive structures such as proof mass. The smooth surface avoids both the defects and the loss to the thickness brought about by the notching effect that is helpful to improve the reliability of the MEMS devices. The rough surface avoids the stiction under structures with a large area. A reduced MIMU was fabricated by such a process. The test results showed that scale factors of the X/Y -axis accelerometer and Z -axis gyroscope were about 19.11 mV/g and 15.6 mV/°/s at one atmosphere, respectively. The bias stability of the gyroscope was about 129.6°/h with a resolution of 0.0224 /°s/ Hz.