Binzhen Zhang

Design, fabrication, and preliminary characterization of a novel MEMS bionic vector hydrophone

According to the auditory principle of fishs lateral line organ, a novel microelectromechanical systems (MEMS) bionic vector hydrophone used for obtaining vector information of underwater sound field is introduced in this paper. It is desirable that the application of MEMS-based piezoresistive effect and bionics structure may improve the low-frequency sensitivity of the vector hydrophone as well as its miniaturization. The bionic structure consists of two parts: high-precision four-beam microstructure and rigid plastic cylinder which is fixed at the center of the microstructure. The piezoresistor located at the beam is simulated to the hair cell of lateral line and the rigid plastic cylinder is simulated to stereocilia. When the plastic cylinder is stimulated by sound, the piezoresistor transforms the resultant strain into a differential voltage output signal via the Wheatstone bridge circuit. Microfabrication technology has been employed for the fabrication of the microstructure and measurement results are given. The experiment results show that the receiving sensitivity of the hydrophone is -197.7dB (0dB=1V/@mPa). The novel hydrophone not only possesses satisfactory directional pattern as well as miniature structure, but also has good low-frequency characteristics, and satisfies the requirements for low-frequency acoustic measurement.

An Omnidirectional Polarization Detector Based on a Metamaterial Absorber

The theory, design, simulation, fabrication, and performance of an omnidirectional polarization detector (PD) with two resonances located in the X and Ka ranges based on a metamaterial absorber (MMA) are presented in this paper. The sandwich structure of PD is composed of 0.1 μm periodic “I” shaped patches on the metasurface, a dielectric of 200 μm FR-4 on the interlayer, and a 0.3 μm copper film on the substrate. PD absorptivity is first used to reflect and describe the polarization of the incident wave. The numerical results, derived from the standard full wave finite integration technology (FIT) of CST 2015, indicates that the designed PD shows polarization sensitivity at all incidence angles. The effects on absorptivity produced by the incidence angles, polarization angles, and materials are investigated. The amplitude of absorptivity change caused by polarization reaches 99.802%. A laser ablation process is adopted to prepare the designed PD on a FR-4 board coated with copper on the double plane with a thickness that was 1/93 and 1/48 of wavelength at a resonance frequency of 16.055 GHz and 30.9 GHz, respectively. The sample test results verify the designed PD excellent detectability on the polarization of the incident waves. The proposed PD, which greatly enriches the applications of metamaterials in bolometers, thermal images, stealth materials, microstructure measurements, and electromagnetic devices, is easy to mass produce and market because of its strong detectability, ultrathin thickness, effective cost, and convenient process.

Design and Fabrication of Micro Hemispheric Shell Resonator with Annular Electrodes

Electrostatic driving and capacitive detection is widely used in micro hemispheric shell resonators (HSR). The capacitor gap distance is a dominant factor for the initial capacitance, and affects the driving voltage and sensitivity. In order to decrease the equivalent gap distance, a micro HSR with annular electrodes fabricated by a glassblowing method was developed. Central and annular cavities are defined, and then the inside gas drives glass softening and deformation at 770 °C. While the same force is applied, the deformation of the hemispherical shell is about 200 times that of the annular electrodes, illustrating that the deformation of the electrodes will not affect the measurement accuracy. S-shaped patterns on the annular electrodes and internal-gear-like patterns on the hemispherical shell can improve metal malleability and avoid metal cracking during glass expansion. An arched annular electrode and a hemispheric shell are demonstrated. Compared with HSR with a spherical electrode, the applied voltage could be reduced by 29%, and the capacitance could be increased by 39%, according to theoretical and numerical calculation. The surface roughness of glass after glassblowing was favorable (Rq = 0.296 nm, Ra = 0.217 nm). In brief, micro HSR with an annular electrode was fabricated, and its superiority was preliminarily confirmed.

A Novel MEMS Based Piezoresistive Vector Hydrophone for Low Frequency Detection

Presented in this paper, is a MEMS-based piezoresistive vector hydrophone. It is desirable that the application of piezoresistive effect and ingenious structure of the hydrophone may improve the low-frequency sensitivity of vector hydrophone as well as its miniaturization. The structure of this hydrophone consists of two parts: high-precision four-beam micro-structure and rigidity plastic cylinder which has the same density of water. The four-beam micro-structure consists of four vertical cantilever beams, and the whole structure is completely axial symmetry in the xoz plane and yoz plane. The fabrication of the micro-structure is completed by means of standard silicon-based MEMS technology, the properties of prepared vector hydrophones has been measured both by vibration-platform and in sound absorbing pool. The experiment results show that fabricating vector hydrophone based on theory of piezoresistive effect and MEMS technology is feasible. Both finite element modelling and experimental result give very close results of the resonance frequency of the device. This kind of hydrophone not only has several advantages such as small volume, light weight as well as simple structure, but also possesses directional pattern in form of 8-shape.

Design a high-g bridge-type accelerometer using GaAs/In x Ga 1-x As/AlAs thin films

In this paper, we present a novel GaAs microaccelerometer based on sensing elements of GaAs/InxGa1-xAs/AlAs thin film. The structure of which contain two suspended flexural beams and a central proof mass configuration. The sensing element consists of double barrier heterostructure comprising a GaAs quantum well and two AlAs potential barrier structures. The finite element method (FEM) is used to stimulate the function of microaccelerometer and sensing element locate in the place where the stress is maximal on the beam. In addition, the sensing element and proof mass are successfully fabricated by double airbridge technique and control holes technique separately. Finally, the static and dynamic experiments have conducted on the sensing element and accelerometer, respectively. The measured dynamic sensitivity of GaAs Piezoresistor Accelerometer can reach to 60 muVg-1.

Research for High Overloading Micro Control System Based on Piezoceramics Actuator

According to the design demand of high overloading, quick response and micro-volume of attitude control system based on intelligent munitions, the micro control system based on warhead deflection angle control method is researched systematically. This paper describes detailedly the method of warhead attitude control and fabrication of piezoceramics actuator with signal detection and control circuit. The experiment testifies that this system has better ability of anti-overloading and maneuverability, and is easy to be integrated. It cant only satisfy the technical request of intelligent munitions, but also apply to micro-nano-actuating field of control system in military defense, aviation and spaceflight etc.

An Acoustic Sensor with the Resonant Tunnelling Effects of GaAs/AlAs/InGaAs Hetero Structures

This paper reports an acoustic sensor based on AlAs/InGaAs/GaAs resonant tunnelling diode (RTD). The RTD is incorporated in a 10 mum thick cantilever using inductivity coupled plasma (ICP) technology and the fabrication of the cantilever diaphragm is based upon micro machined control holes technology by ICP too. Pressure applied to RTD changes its current-voltage characteristics, which can be used on sensor design. Comparing with sensors using Si technology, this type of sensor has excellence features, such as indecisive of temperature effects, high sensitivity, half-digital outputs and so on. Because of the restriction of RTDs fabricated technology, the negative differential region (NDR) of RTD hasnt been used in this batch, which induces the sensors sensitivity is not very high. Elementary measurements show the acoustic sensor has a good frequency response in 500 HZ region between 1.3 KHZ and 1.8 KHz, and its sensitivity up to 0.1 muv/Pa with frequency f=1.3 KHZ.

A Cantilever Accelerometer Based on Resonant Tunneling Diode

This paper presents a GaAs piezoresistive accelerometer based on the GaAs/AlAs Resonant Tunneling Diode (RTD). As the sensing unit, the resonant tunneling thin films are designed and integrated on the cantilever. In order to decrease the parasitic capacitance and control the thickness of the cantilever accurately, RTD and seismic mass are successfully fabricated by airbridge and control hole technique separately. The static pressure experiments prove that the piezoresistive coefficient of resonant tunneling device change with the bias voltage. Under 0.75 V bias voltage, the microaccelerometer shows the sensitivity of 87 muVV -1 g -1 and non-linearity is less than 0.2% in the positive difference resistance region.

The design of nano-film tunneling-effect micro gyroscope

The micro gyroscope based on the nano-film tunneling effect is designed and the mesoscopic piezoresistive effect theory of resonant tunneling film structure (RTS) is also researched in this paper. In the mean time, the structure and its material of the RTS are designed and manufactured. The RTS which can explain the resonant tunneling effect reduces the parasitic capacitance of the sensor, improves the negative resistance characteristics of the sensitive film and it can be used in micro gyroscope. Meanwhile, the structure and the parameters of the tunneling effect gyroscope based on the resonant tunneling effect are established. The principle and the simulation of the gyroscope are also made and the simulation results are consistent with the principle.

A GaAs micromachined accelerometer with frequency output based on resonant tunneling diodes

The paper reports a novel GaAs micromachined accelerometer with frequency output based on resonant tunneling diodes (RTD). The sensitive unit of the accelerometer is the RTD which is located on GaAs beams. Based on the piezoresistive effect of RTD and the frequency characteristics of RTD oscillator, the accelerometer transducers acceleration into frequency output. This kind of accelerometer has been fabricated by surface processes and GaAs micromachining bulk etch processes