In this paper, the structure design and operating principle is introduced to micromachined gyroscope with electrostatic drive and piezoresistive detection. In the paper, the piezoresistive effect of multi-barrier nano-film is used as detection method, which achieves high piezoresistive sensitivity compared with Silicon piezoresistive device. The gyroscope structure and multi-barrier nano-film device is fabricated by using heteroepitaxy GaAs film on Si substrate which implements the process compatible. The natural frequencies of gyroscope are determined from the modal analysis.
In this paper, a gyroscope with novel structure is designed and fabricated by the GaAs surface micromaching technology and GaAs bulk micromachining processes technology to achieve an integration of RTD and gyroscope structure. The structure and properties of RTD are tested by Transmission electron microscopy and Aglient 4156C semiconductor analyzer, and then the key parameters of gyroscope are measured by application of Scanning Electron Microscope. The effect of packaged gyroscope is tested by Polytec Micro-system analyzer. The problems in the fabrication process are analyzed and summarized, which have certain reference significance for the further study.
Nickel hollow spheres (NHSs) with different diameter have been synthesized by the autocatalytic reduction method. The morphology, size distribution and magnetic properties of NHSs were characterized. The results indicate that when the nickel hollow spheres become smaller, mechanism of magnetization reversal varies from motion of domain wall to spin coherent rotation. After the heat treatment process, the grain size of samples becomes bigger and coercivity is enhanced because domain wall is pinned by local magnetic anisotropy induced spontaneously.
By researching and investigating the structure of capacitive gyroscopes, A novel capacitive micromachined gyroscope is proposed and the structure is designed. The method of electrostatic comber drive, capacitive detection of bar structure is used for the structure, and these make the gyroscope high sensitivity. The main air damping of the drive mode and detection mode is slide film damping, it is possible to make the gyroscope achieve high Q-values at atmospheric pressure. The decoupled gyroscope is designed, too. By large numbers of simulation analysis, frequencies of the first six steps mode are gained, nature frequencies of drive mode and sense mode of gyroscope are a close match, and rationality of the structure is validated. At last, the structure encapsulated is presented.
Resonant tunneling diode (RTD) is a bipolar negative resistance device with the features of high speed, high frequency, low voltage and power, has been proved to have mesopiezoresistive effect, and the current-voltage characteristics of RTD is a function of stress. In the paper, the mesopiezoresistive effect of resonant tunneling diodes and Coriollis effect are both used in the research of gyroscope, so a novel gyroscope structure is proposed. The feasible fabrication process is designed according to present process technology, and the gyroscope is fabricated by GaAs surface micromachining processes and bulk micromachining technology. By the driven experiment it is verify that the gyroscope can be successfully driven. And the range of fabricated gyroscope natural frequency is also obtained, which is larger than 4KHz.
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