In the paper, a micromachined artificial vector hydrophone arises from a biological inspiration, the fish hair cell is presented. It is desirable that the application of piezoresistive effects combined with ingenious bionic structure and MEMS technology may improve the lowfrequency sensitivity of the vector hydrophone as well as its miniaturization. Modeling processes for realizing the artificial hair cell hydrophone, along with preliminary characterization results in terms of sensitivity, frequency response and directivity patterns are also introduced. The microstructure of the sensor consists of four vertical cantilever beams with attached rigid plastic cylinder in the center of the structure. By locating eight piezoresistors logically formed the Wheatstone bridges; they can detect two components of underwater acoustic signal simultaneously. The prepared vector hydrophone has been measured in the standing wave field finally. The experiment results show that the vector hydrophone has good low-frequency characteristic, the free-field voltage sensitivity is -197.2 dB (0 dB = 1 V/lPa) at 400 Hz with a about 2 dB one-third octave positive slope over the 40-400 Hz bandwidth. The depth of pits of the directivity pattern is about 34.6 dB.
There are three fields in electronic equipment such as structure deformation (S), temperature (T), and electromagnetic (EM) fields. Both deformation and temperature will affect the electromagnetic shielding performance of the equipment considerably, particularly in the case of enclosure with small volume and high packaging density. Because the position of electronic device and the shape of outlet will be changed with structural deformation, there must be therefore an adherent relationship among three fields. To begin with, this paper presents a three-field-coupled model called STEM. Then, to enhance the capability of electromagnetic shielding of the equipment, an efficient way is to attach absorbing material to the inside of it. Under the condition of pregiven material characteristics itself, the position and size of absorbing material are of significant effort on electromagnetic shielding. The optimization model based on STEM is developed in this paper. Next, the numerical and practical experiments of an actual enclosure are given to demonstrate the feasibility and validity of the model and methodology.
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