Key Engineering Materials Vols. 562-565

Abstract: This paper presents a new type of micro self-powered wireless analog sun sensor. The mask with aperture of the sun sensor, developed by glass coated process, reduces the impact on accuracy caused by second reflection of the light, and also promotes system’s external thermal radiation ability. With aluminum substrate process, the processing circuit is integrated on the bottom cover of the sun sensor, which saves the conventional processing circuit needed space and reduces the complexity of system’s structure. Self-powered and wireless data transmission improve the system’s application flexibility. The simulation results and preliminary experiments show that the accuracy of the system has the ability to reach 0.2° in the whole 120°×120° FOV and the solar cells’ minimum output power is 90mW which is able to meet the power consumption requirements of the system circuits.

Abstract: In this paper, a SOI-MEMS (silicon on insulator- micro electro mechanical system) pizeoresistive atmosphere pressure sensor is presented using anodic bonding. Differently from the prevailing fabrication process of silicon piezoresistive pressure sensor: the device layer monocrystalline of SOI silicon wafer is used as the strain gauge with a simple deep etching process; and the SiO2 layer of SOI silicon wafer as the insulator between strain gauge and substrate. The whole fabrication processes of the designed sensor are very simple, and can reduce the cost of sensor. The Pressure-Voltage characteristic test results suggest a precision within 0.14% in linear fitting. It is shown that the temperature coefficient is 2718ppm/°C from the Typical temperature curve of the pressure sensors.

Abstract: This paper presents an improved phase lock loop for a micromechanical vibrating gyroscope with a carrier modulation. The loop keeps the gyroscope working at the resonant frequency of its drive mode. Digital signal processing is adopted in design of the loop and Xilinx virtex4 series FPGA is used. Compare with the conventional way, it decreases the resources in FPGA including registers, LUTs, and DSP48s. The realization shows a reduction of 51.06% for registers, 52.68% for LUTs and 18.18% for DSP48s. Besides, the loop has good portability for different devices which have different resonant frequencies due to the fabrication error. No adjustment is needed unlike the conventional loop whose reference phase has to be adjusted manually.

Abstract: 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.

Abstract: The screening of urine human serum albumin (HSA) is significant for the early diagnosis and intervention of the nephropathia. This study developed sensitive HSA detection assay with a self-made portable-SPR biosensor based on the reflection light intensity interrogation. Anti-HSA monoclonal antibody was immobilized onto the gold sensing area and a directive assay for HSA was developed. A detection range of 1–100μg/mL HSA was found. The described label-free, real-time immunoassay for the quantification of HSA in urine is a rapid, sensitive, alternative method available for the clinic detection.

Abstract: A novel highly symmetrical 16-beam sandwich structure Z-axis differential capacitance accelerometer is presented. In this design, the proof mass is suspended symmetrically by double-side of 16 straight beams with highly uniform dimension which can reduce the cross-axis sensitivity and rotational influences dramatically. Parameters of the beam-mass structure were analyzed and optimized by finite element analysis (FEA) software. The micro accelerometer is based on bulk-micromachining by DRIE and KOH anisotropic wet etching technologies. The beam-mass structure was released by anisotropic wet etching on both device layer sides simultaneously. The fabricated accelerometer was measured over the maximum range of 30g gravity field, results of measurement show that the close-loop sensitivity is 80mV/g, the nonlinearity is 0.27%, and the bias stability is 0.63mg for an hour.

Abstract: Quartz vibrating gyroscope is a kind of angular rate sensor which is the compromise between the high performance and the small volume. Improvement of the performance is a focus of reach. In this paper, a sine-wave exciting method is discussed. A sine-wave exciting circuit is design and processed with 0.5μm CMOS processing technology. During comparing the sine-wave exciting response and the square-wave one, the sine-wave exciting circuit is more beneficial to improve the performance of the quartz vibrating gyroscope.

Abstract: 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.

Abstract: In allusion to low accurary and poor stability of the initial alginment based on the acceleration sensor, the HMM (Hidden Marco Model) / steady state Kalman filter is designed to solve the problem above. C8051F340 is used to sample the acceleration data of the MEMS acceleration sensor Model1221, then the digital low-pass filter is used to filter the acceleration data. The steady state Kalman filter based on the second order HMM model. The initial alignment algorithm outputs the angle value. The experiments demonstrate that the the HMM / steady state Kalman filter is more stable and more precise than the traditional algorithm.

Abstract: This paper reports on the magnetic field distribution and magnetic circuit calculating method of micro generator. A micro axial-flux electromagnetic generator is designed as size of Φ6mm×3mm. Traditional magnetic circuit analysis methods are used to retrieve the air-gap magnetic density on no-load micro generator in operation. FEA is done for the micro generator model using magnetic field numerical simulation software. The main parameters of no-load magnetic field and the waveform of induced EMF are obtained. Comparing the results obtained from the magnetic circuit analysis and numerical simulation, the error of air magnetic density is less than 2.54% and the error of the maximum value of induced EMF is less than 2. 68%. The results suggest that magnetic circuit analysis methods can be used for magnetic field analysis of micro axial-flux electromagnetic generators, and be helpful to provide guidance for designs.