微型磁通门式磁敏感器(MEMSMag)

基于MEMS技术的微型磁通门式磁敏感器是磁场测量技术和微机电系统(MEMS)技术交叉研究领域的一个热点,在航空航天领域特别是在纳型/皮型卫星技术中有着重要的应用.本文介绍了该类磁敏感器所运用的磁通门效应的原理.从磁芯、线圈和整体结构布局等方面分析了现有的各种微型磁通门式磁敏感器的结构特征.并依据磁通门原理和各种微型磁通门式磁敏感器的结构特点,设计了一种两轴微型磁通门式磁敏感器.这种新型的磁敏感器具有对称结构、闭合磁路、差动形式、柔性连接等显著特点.     

A fluxgate magnetometer with a metallic glass core

A square-wave excited pulse-height fluxgate circuit is described, using a metallic glass core fluxgate and a minimum amount of active components. High reliability and linearity have been achieved.     

基于三端式磁通门技术的航空货运磁检仪

由于微弱的杂散磁场对飞机的导航系统和控制信号均有干扰,国际航空运输守则(International Air Transport Association简称IATA)将磁性货物列为第9类危险品,在收运时加以限制。该文重点阐述一种适用于对空运货物进行杂散磁场检测的磁检仪的设计。     

Low-power CMOS current-conveyor relaxation oscillators

The purpose of this paper is to investigate in detail the design of a current conveyor circuit suitable for implementation of low-voltage, low-power RC and crystal oscillators, and to show the design and performances of such oscillators. All circuits are based on the Fabre-Normand translinear conveyor. Circuits are biased in the subthreshold region whenever possible     

Effects of driving mode and optimal material selection on a residence times difference-based fluxgate magnetometer

In this paper, analytical and experimental results on fluxgate magnetometers, intended to sense dc magnetic field, that make use of a readout technique based on the estimation of the residence times in the stable attractors are presented. The approach, exploiting the inherent nonlinear character of the bistable core dynamics, is based on the time-domain characterization of the transitions between the two saturation states of the hysteresis loop that is inherent in the ferromagnetic core dynamics. This readout technique affords the possibility of low amplitude and frequency reference (or bias) driving signals (sinusoidal or triangular), compared to conventional fluxgates, thereby reducing the device power requirements. The efficacy of this strategy is shown through an analytical approach, and via experimental results that suggest guidelines for the optimal design of the device. Considerations of the effects of a suitable choice of the magnetic core (in terms of its hysteresis behavior) have also been included. Experiments, carried out on miniaturized laboratory fluxgate prototypes with different ferromagnetic materials, reveal good performances of the proposed methodology, including suitable sensitivity and resolution, as well as low cost.     

Lab-on-a-disc for fully integrated multiplex immunoassays

This paper presents a cost-effective, rapid, and fully automated lab-on-a-disc for simultaneous detection of multiple protein biomarkers in raw samples such as whole blood or whole saliva. For the diagnosis of cardiovascular disease, here, a novel centrifugal microfluidic layout was designed to conduct the simultaneous detection of high sensitivity C-reactive protein, cardiac troponin I, and N-terminal pro-B type natriuretic peptide based on a bead-based sandwich type enzyme-linked immunosorbent assay (ELISA). Three reaction chambers are initially interconnected for the common processes such as sample injection, incubation, and washing and then isolated on-demand for the independent processes such as substrate incubation and final detection. The assay performances such as the limit of detection and the dynamic range were comparable with those of the conventional ELISA despite the significant reduction of the minimum sample volume (200 μL), the amount of washing buffer (700 μL), and the total process time (20 min).     

n-InAs nanopyramids fully integrated into silicon

InAs with an extremely high electron mobility (up to 40,000 cm(2)/V s) seems to be the most suitable candidate for better electronic devices performance. Here we present a synthesis of inverted crystalline InAs nanopyramids (NPs) in silicon using a combined hot ion implantation and millisecond flash lamp annealing techniques. Conventional selective etching was used to form the InAs/Si heterojunction. The current-voltage measurement confirms the heterojunction diode formation with the ideality factor of η = 4.6. Kelvin probe force microscopy measurements indicate a type-II band alignment of n-type InAs NPs on p-type silicon. The main advantage of our method is its integration with large-scale silicon technology, which also allows applying it for Si-based electronic devices.     

Compact CMOS current conveyor for integrated NEMS resonators

A fully integrated nanoelectromechanical system (NEMS) resonator together with a compact built-in complementary metal-oxide-semiconductor (CMOS) interfacing circuitry is presented. The proposed low-power second generation current conveyor circuit allows measuring the mechanical frequency response of the nanocantilever structure in the megahertz range. Detailed experimental results at different DC biasing conditions and pressure levels are presented for a real mixed electromechanical system integrated through a combination of in-house standard CMOS technology and nanodevice post-processing based on nanostencil lithography. The proposed readout circuit can be adapted to operate the nanocantilever in closed loop as a stand-alone oscillator.     

An integrated circuit with transmit beamforming flip-chip bonded to a 2-D CMUT array for 3-D ultrasound imaging

State-of-the-art 3-D medical ultrasound imaging requires transmitting and receiving ultrasound using a 2-D array of ultrasound transducers with hundreds or thousands of elements. A tight combination of the transducer array with integrated circuitry eliminates bulky cables connecting the elements of the transducer array to a separate system of electronics. Furthermore, preamplifiers located close to the array can lead to improved receive sensitivity. A combined IC and transducer array can lead to a portable, high-performance, and inexpensive 3-D ultrasound imaging system. This paper presents an IC flip-chip bonded to a 16 x 16-element capacitive micromachined ultrasonic transducer (CMUT) array for 3-D ultrasound imaging. The IC includes a transmit beamformer that generates 25-V unipolar pulses with programmable focusing delays to 224 of the 256 transducer elements. One-shot circuits allow adjustment of the pulse widths for different ultrasound transducer center frequencies. For receiving reflected ultrasound signals, the IC uses the 32-elements along the array diagonals. The IC provides each receiving element with a low-noise 25-MHz-bandwidth transimpedance amplifier. Using a field-programmable gate array (FPGA) clocked at 100 MHz to operate the IC, the IC generated properly timed transmit pulses with 5-ns accuracy. With the IC flip-chip bonded to a CMUT array, we show that the IC can produce steered and focused ultrasound beams. We present 2-D and 3-D images of a wire phantom and 2-D orthogonal cross-sectional images (Bscans) of a latex heart phantom.     

A CMOS smart pixel for active 3-D vision applications

A CMOS smart pixel aimed at three-dimensional vision applications is introduced. It is suitable for scannerless laser ranging systems which employ the indirect time-of-flight measuring technique to recover distance information. The pixel is operated with trains of light pulses generated by an external source to illuminate the scene and contains most of the processing electronics to perform signal accumulation and noise reduction operations. The smart pixel architecture includes an N-well photodiode plus a self-biasing voltage amplifier and a switched-capacitor fully differential stage. The pixel is fabricated in standard CMOS 0.6 /spl mu/m technology and measures 180/spl times/160 /spl mu/m/sup 2/ (including the photodiode) with a fill factor of 14%. Electrooptical test results confirm the smart pixel functionality in a range of distance from 3 m to 9 m, and the accuracy achieved for preliminary distance measurements is 15 cm. Both the accuracy and the extension of the range of distance are supposed to be improved by reducing setup and environmental noise contributions that limit the pixel performance.     

A fully integrated temperature compensation technique forpiezoresistive pressure sensors

A fully integrated temperature compensation technique for piezoresistive pressure sensors is presented. The technique is suitable for batch fabricated sensors operable over a temperature range of -40°C-130°C and a pressure range of 0-310 kPa. The implementing hardware for the technique is developed and verified through PSpice and VHDL simulations. The technique is very effective for pressure values below 240 kPa and provides reasonable results for higher pressures. The technique is structurally simple and uses standard IC fabrication technologies     

50-nm fully depleted SOI CMOS technology with HfO/sub 2/ gate dielectric and TiN gate

In this paper, we demonstrate for the first time CMOS thin-film metal gate FDSOI devices using HfO/sub 2/ gate dielectric at the 50-nm physical gate length. Symmetric V/sub T/ is achieved for long-channel nMOS and pMOS devices using midgap TiN single metal gate with undoped channel and high-k dielectric. The devices show excellent performance with a I/sub on/=500 /spl mu/A//spl mu/m and I/sub off/=10 nA//spl mu/m at V/sub DD/=1.2 V for nMOSFET and I/sub on/=212 /spl mu/A//spl mu/m and I/sub off/=44 pA//spl mu/m at V/sub DD/=-1.2 V for pMOSFET, with a CET=30 /spl Aring/ and a gate length of 50 nm. DIBL and SS values as low as 70 mV/V nand 77 mV/dec, respectively, are obtained with a silicon film thickness of 14 nm. Ring oscillators with 15 ps stage delay at V/sub DD/=1.2 V are also realized.     

A fully integrated monolithic microchip electrospray device for mass spectrometry

A novel microfabricated nozzle has been developed for the electrospray of liquids from microfluidic devices for analysis by mass spectrometry. The electrospray device was fabricated from a monolithic silicon substrate using deep reactive ion etching and other standard semiconductor techniques to etch nozzles from the planar surface of a silicon wafer. A channel extends through the wafer from the tip of the nozzle to a reservoir etched into the opposite planar surface of the wafer. Nozzle diameters as small as 15 microm have been fabricated using this method. The microfabricated electrospray device provides a reproducible, controllable, and robust means of producing nano-electrospray of a liquid sample. The electrospray device was interfaced to an atmospheric pressure ionization time-of-flight mass spectrometer using continuous infusion of test compounds at low nanoliter-per-minute flow rates. Nozzle-to-nozzle signal intensity reproducibility using 10 nozzles was demonstrated to be 12% with single-nozzle signal stability routinely less than 4% relative standard deviation (RSD). Solvent compositions have been electrosprayed ranging from 100% organic to 100% aqueous. The signal-to-noise ratio from the infusion of a 10 nM cytochrome c solution in 100% water at 100 nL/min was 450:1. Microchip electrospray nozzles were compared with pulled capillaries for overall sensitivity and signal stability for small and large molecules. The microchip electrospray nozzles showed a 1.5-3-times increase in sensitivity compared with that from a pulled capillary, and signal stability with the microchip was 2-4% RSD compared with 4-10% with a pulled capillary. Electrospray device lifetimes achieved thus far have exceeded 8 h of continuous operation and should be sufficient for typical microfluidic applications. The total volume of the electrospray device is less than 25 pL, making it suitable for combination with microfluidic separation devices.     

Colorimetric porous photonic bandgap sensors with integrated CMOS color detectors

In this paper, the development of a novel colorimetric sensor system based on the integration of complementary metal-oxide-semiconductor (CMOS) color detectors with a modified porous polymeric photonic bandgap sensor is reported. The color detector integrated circuit IC is implemented with AMI (AMI Semiconductor) 1.5 /spl mu/m technology, a standard CMOS fabrication process available at MOSIS (http://www.mosis.org). The color detectors are based on the spectral responses of buried double junctions (BDjs) and stacked triple junctions (STJs); the ratio of the photocurrents at the junctions provides spectral information. Both types of color detectors are characterized with a monochromator, and the results are compared. The BDJ color detector is used with a porous photonic bandgap reflection grating whose reflection spectra shifts as a function of the concentration of vapor analyte present. The experimental results verify that the color change of the photonic crystal can be detected and correlated to the change in analyte concentration. The entire system is compact and low power.     

A fully automatic 3-D analysis tool for expansion chamber mufflers

The matrix condensation technique in conjunction with the substructuring principle has been previously used to model complex commercial automotive mufflers. Though complete 3-D finite element modelling is partially eliminated, it still requires the nodal-coordinate data and connectivity data of the elements forming the segment of each substructure. It also demands the connectivity of the degrees of freedom left after matrix condensation. Thus, the data preparation phase is tedious and cannot be claimed to be simple. Moreover, the existing FEM code requires the user to have a knowledge of acoustic theory and finite element modelling. This paper describes a way to completely eliminate the data preparation phase. Given the geometric dimensions of the muffler as input, the muffler performance is obtained as the output. The results obtained are compared with analytical and experimental results for simple as well as extended-tube expansion chambers, with or without an offset.     

Toward a fully integrated positive-pressure driven microfabricated liquid analyzer.

A versatile integrated analyzer with a flow-programmed injection strategy and multiwavelength detection is described with applications toward sampling, flow injection analysis, and capillary separations. Continuous near-real-time sampling is a major benefit of the flow-programmed injection technique. Injection volumes ranging from 250 pL to several microliters were made without electrophoretic flow. Multiwavelength grating light reflection spectroscopy (GLRS) and transmission absorbance spectroscopy were performed simultaneously in a detection volume of 150 pL. The utility of these detection methods for refractive index (RI) and absorbance detection in capillary channels is demonstrated through analysis of salt, indicator, and dyes. GLRS is a unique, selective, and path-length-independent technique for probing RI, absorbance, and other optical properties. A limit of detection (LOD) of 170 microM was achieved for GLRS interferometric detection of FD&C Red #3, which corresponded to 2.6 fmol of analyte in the 150-pL detection volume. A LOD of 2 mM for phosphate buffer, or 3 fmol in the 150-pL detection volume will also be demonstrated. A siloxane coating on the GLRS grating was employed as a sensing layer to probe interactions between the sample and stationary phase. The combined GLRS interferometric response provided insight into both optical and chromatographic properties of samples. Open tubular capillary liquid chromatography with multidimensional multiwavelength detection is demonstrated for the analysis of three food dyes. Separation efficiency, N, of 16,000 was achieved for an unretained dye peak eluting at 12 min. Integration of novel sampling and detection schemes makes this a broadly applicable liquid analyzer.     

An integrated microsystem for 3-D magnetic field measurements

In this paper, we present a portable, battery-operated, three-dimensional magnetic microsystem (magneto-dosimeter), intended for monitoring the workers' exposure to magnetic fields in particular working environments, such as hospitals or physics laboratories. The proposed microsystem is based on a multichip module containing three equal channels for the three components of the magnetic field measurement, a microprocessor, and a memory. Each single-chip channel detects the magnetic field, converts it into the digital domain, and delivers the result to the microprocessor by means of an on-chip serial interface. The single-chip channel, fabricated in a 0.8-μm CMOS technology, is sensitive to magnetic fields ranging from -200 to +200 mT, achieving 12 bits of resolution, 11 bits of linearity, and an overall accuracy better than 1% in the temperature range from -20 to +80°C     

Lithium-niobate-based surface acoustic wave oscillator directly integrated with CMOS sustaining amplifier

In this study, a LiNbO(3)-based SAW resonator was directly integrated with a CMOS sustaining amplifier using new wafer-bonding-based integration technology. The developed integration technology has overcome the large thermal expansion mismatch between LiNbO(3) (14 to 15 ppm/K along the a-axis) and Si (2.6 ppm/K) by temporary wafer supporting and low-temperature Au-Au bonding. Two kinds of bonding, UV polymer bonding for temporary wafer supporting and Au-Au bonding following plasma surface activation, are key process technologies. A 500-MHz one-chip SAW oscillator was prototyped and evaluated. A low phase noise of -122 dBc/ Hz at 10 kHz offset and -160 dBc/Hz at 500 kHz offset was achieved.     

Comparison between 2-D cross correlation with 2-D sub-sampling and 2-D tracking using beam steering

We have previously presented multi-dimensional sub-sample motion estimation techniques that use multi-dimensional polynomial fitting to the discrete cross-correlation function to jointly estimate the sub-sample motion in all three spatial directions. Previous simulation and experimental results showed that these estimators significantly improve the performance of the motion estimation in 2-D and 3-D. In this short communication, we present additional simulation results and compare these techniques to 2-D tracking using beam steering. The results show that beam steering technique performs better in estimating the motion vector especially the lateral component.