A 50,000g three-axis accelerometer using a single proof mass is presented. The sensitive structure is made of a single proof mass and eight cantilever beams. Twelve piezoresistors are placed on the cantilevers symmetrically, which can be used to detect 3-dimensional acceleration. The symmetric placement of the piezoresistors brings the reasonable sensitivity and simultaneously decreases the cross-axis sensitivity significantly. Simulation results show that the sensitivity in X-, Y- and Z-axis are 0.806uV/g, 0.806uV/g and 3.71uV/g respectively with 5V supply and the cross-axis sensitivities are all less than 2.4%, which ensures the high performance of the three-axis accelerometer.

No abstract

This is mainly due to the high chemical reactivity and spontaneous etching nature of the fluorine radicals towards silicon, and the high volatility of the silicon fluorides as reaction products. Anisotropy can only be achieved by the inclusion of sidewall passivation schemes to the process. The existing approaches to deep reactive ion etching (DRIE) of silicon are distinguished by the way sidewall passivation is achieved, the key to anisotropy and overall performance of the etch process. Cryogenic etching and the so-called Bosch process with alternating etch and passivation cycles are the two most well-known high-aspect-ratio silicon etch processes and are discussed in this paper.

No abstract

According to sensitive structure of vector hydrophone which imitates fish lateral line cells, a novel encapsulation of polyurethane is proposed, that is, using polyurethane, the same material as sound-transparent cap, instead of castor oil to package. It is desirable that the novel encapsulation may effectively solve the problem of vector hydrophone’s low sensitivity. On the basis of analysis theoretical model of sound-transparent cap’s three layer mediums, this paper simulated the whole encapsulation structure by ANSYS. It can be concluded that the sensitivity is 0.267mV/Pa, resonance frequency is 1151.37 Hz. Finally, the prototype of the vector hydrophone was fabricated and preliminary characterization tests of the hydrophone were performed. Results show that the novel encapsulation hydrophone possesses satisfactory directional pattern and the free-field voltage sensitivity is -188.9 dB, which is 8.8dB higher than castor oil encapsulation.