Xiao Sheng Wu

A PCR Chip with Reusable Electrodes and its Temperature Analysis

This paper presents a new micromachined PCR chip with separable electrodes part and reaction chamber part. The electrodes part, employing Pt film resistor as heaters and sensors, is reusable, and the chamber part is a disposable PDMS-GLASS bonded structure. This PCR chip with reusable electrodes can largely reduce fabrication cost. COMSOL software is used to simulate the temperature distribution of the designed chip and then use infrared thermometer (NEC R300SR) to verify temperature distribution of the fabricated chip. The test results turned out to perfectly fit the simulation of temperature distribution, which provides reliable basis for further PCR amplification experiment.

The Study on After-Treatment System and Algorithm of Piezoelectric Micromachined Modal Gyroscope

Piezoelectric Solid-State Micro-machined Modal Gyroscope is a new kind of gyroscope sensor based on MEMS. According to the characteristics of the gyroscope signal, the after-treatment processing system is designed and implemented, including A/D convertor by AD7656 and data storage by SD card. After applying Kalman filter to the digital signal on DSP, 71.8% decrease of standard variance of initial signal is achieved remarkably, which lays the foundation for the practical application of piezoelectric micro-machined modal gyroscope.

Design and Fabrication of a Novel Biaxial Piezoelectric Micro-Gyroscope

Despite the popularity of piezoelectric vibratory micro-gyroscope in the past decades for their small size, low cost, batch fabrication and energy efficient, most of them can only detect single axis angular rate. In this paper, a novel biaxial piezoelectric micro-gyroscope fabricated with PZT wafer is proposed. To acquire two-axial angular rate sensing, a bouncing mode of the vibrator is utilized as the drive mode and two rocking modes are used as the sense modes. PZT is used as the vibration body instead of transducer, which enhances the drive and sense efficiency of the sensor. In this paper, the structure and working principle of the novel biaxial piezoelectric micro-gyroscope are introduced firstly. In addition, modal analysis has been made to research the voltage distribution of the piezoelectric vibrator and the drive and sense electrodes of the gyroscope are designed. By the optimization design of the proof mass, the frequency split between the drive mode (bouncing mode) and sense modes (rocking modes) is reduced and the sensitivity of the gyroscope is improved. Harmonic analysis has been made to research the Coriolis Effect of the gyroscope. The data get from the harmonic analysis is demodulated by Matlab and the sensitivity is given. The simulation results verify the principle of the novel biaxial piezoelectric micro-gyroscope. With the optimized design, the sensor is fabricated with MEMS technology at last.

A Novel Flexible Shear Stress Sensor Array with Double Hot-Wires Based on MEMS

Design, production and calibration of a novel flexible shear stress sensor array with double hot-wire based on MEMS are presented in this paper, which can be applied to measure the surface shear stress of air craft or underwater vehicles. The sensor array is successfully fabricated by MEMS process, the electrical bond pads of which are located at the backside, thus greatly reducing the interference of the measured flow filed. The calibration has been carried out in the wind tunnel experiment, and the value of calibration factor is 8.35mV/ (m/s) in a flow velocity range from 0 to 35 m/s. The results of test experiments prove that the shear sensor array is well capable of measuring the flow velocity of boundary layer.

A Simple and Practicable PCR-Microchip with Bubble-Free Stationary Chamber

This paper reports on a simple and practicable biochip for polymerase chain reaction (PCR). The micro biochip (12mm×12mm) is a hybrid type which is composed of a polydimethylsiloxane (PDMS) cover with a hexagonal chamber and a glass substrate integrated with platinum (Pt) microheater and microsensor. Bubble formation has been reported as a big problem with PCR chips. In this paper we present a simple and practicable operation schedule to get a bubble free chip, in which a successful PCR process was guaranteed.

Study on Driving Technology of Piezoelectric Solid-State Micro Gyroscope

In order to compensate the noise brought by piezoelectric gyroscope or external environment and track the resonance frequency, Closed Loop Driving Circuit (CLDC) of piezoelectric solid-state micro gyroscope is proposted in the paper which will stabilize the driving voltage value and keep the resonance frequency tracked. CLDC mainly contains Phase Lock Loop (PLL) circuit, Automatic Gain Circuit (AGC). Experimental results show that the fluctuation of reference voltage is within ±7mv, while the fluctuation of reference voltage in Open Loop Driving Circuit (OLDC) without noise compensation is ±23mv. The frequency of CLDC drifts within 0.03 kHz with the resonance frequency of 357.9 kHz while the OLDC can’t track any drifting.

Modal FEM Analysis Using Weak Form Equations for a Microgyroscope with Bulk Giant Magnetostrictive Material (GMM) Resonator

The structure and operation principle of a novel solid MEMS gyroscope with bulk giant magnetostrictive material (GMM) resonator are presented. A finite element method (FEM) for modal analysis of the GMM resonator is employed in which the fundamental magnetoelastic governing equations of the GMM are solved numerically using weak form equations of COMSOL Multiphysics. For a bulk GMM with size of 4×4×4 mm3, it is found that the third order vibration mode with frequency of 182 kHz meets working vibratory mode of the gyro sensor, which is verified by harmonic response analysis. Compared with analogy method which simulates the GMM as piezoceramics, this method is more practically reflect the operation state of GMM resonator of the microgyro due to consideration of Maxwell force in the weak form equations. This paper provides important basis for further full magnetic electromechanical coupling analysis of the microgyroscope.

Structure Optimization of Piezoelectric Micromachined Modal Gyroscope

This paper reports a novel kind of solid micro-gyroscope, which is called piezoelectric micromachined modal gyroscope (PMMG). PMMG has large stiffness and robust resistance to shake and strike because there is no evident mass-spring component in its structure. This work focused on quantitative optimization of the gyroscope, which is still blank for such gyroscope. A set of quantitative indicators were developed to optimize the operation mode and corresponding device size was obtained. By FEM, the harmonic analysis was conducted to find the way to efficiently actuate the operation mode needed. At last, the Coriolis analysis was conducted to show the relation between angular velocity and differential output voltage by the Coriolis force under working condition.

Vibration Analysis of a Micromachined Modal Gyroscope Based on Elastic Body

Micromachined modal gyroscope based on elastic body (MMGEB) is a novel kind of rotating rate sensor, which has large stiffness and robust resistance to shake and strike because there is no evident mass-spring component in its structure. In this paper, the model and working mechanism of MMGEB are proposed first. The modal analysis, the harmonic analysis and Coriolis analysis for the model by the finite element method (FEM) have been conducted. The research in the paper provides theoretical foundation for realizing this micromachined gyroscope.

Modal Analysis of a New Solid Micro-Gyroscope with Bulk Giant Magnetostrictive Material (GMM) Resonator

Employing unique advantage of giant magnetostrictive strain of giant magnetostrictive material (GMM) for improving reference vibration amplitude, a novel bulk GMM solid MEMS gyroscope, which has small and simple structure and is capable of detecting 2-axis angular rate with improved sensitivity, is proposed. The device structure and operation principle of the gyroscope are presented. Using finite element method (FEM), modal analyses, for whole solid GMM cube and for bulk GMM cube composed of multilayer GMM plates, are conducted. The results show that the fourth order vibration mode for the former and the first order vibration mode with lower frequency of dozens of KHz for the latter were found to meet the working vibratory mode of the gyro sensor. This work of the paper provides theory foundation for structural optimization design and fabrication of the microgyroscope.