Two-dimensional numerical analysis of a silicon magnetic field sensor

We present two-dimensional numerical solutions of the coupled, nonlinear, partial differential equations governing the electric potential, carrier drift, diffusion, generation, and recombination in a finite semiconductor slab in the presence of a magnetic field. This enables device modeling for general geometries, doping levels, and injection conditions, where the effect of the magnetic field cannot be expressed simply in terms of Hall voltage, Lorentz deflection, or magnetoconcentration.     

基于硅桥结构的MEMS磁场传感器

提出了一种基于硅桥结构的MEMS磁场传感器结构。其结构由制作在硅桥敏感膜表面的惠斯通电桥和在膜中间沾上铁磁体制成。当传感器处于磁场中时,铁磁体在外磁场中磁化产生磁力,磁力会使硅敏感膜弯曲从而引起压阻改变进而使惠斯通电桥产生电压输出以达到测量磁场的目的。文章通过有限元软件仿真对铁磁体的尺寸进行了优化。实验结果和理论结果较接近。实验测得该传感器最大灵敏度为48mV/T,分辨率为160μT,该传感器可以用来进行强磁场的测量。实验结果结果表明:传感器的重复性和动态响应时间分别约为0.66%和150ms。     

MEMS magnetic field sensor based on silicon bridge structure

A MEMS piezoresistive magnetic field sensor based on a silicon bridge structure has been simulated and tested.The sensor consists of a silicon sensitivity diaphragm embedded with a piezoresistive Wheatstone bridge,and a ferromagnetic magnet adhered to the sensitivity diaphragm.When the sensor is subjected to an external magnetic field, the magnetic force bends the silicon sensitivity diaphragm,producing stress and resistors change of the Wheatstone bridge and the output voltage of the sensor.Good agreeme...     

Vehicle detection using a magnetic field sensor

The measurement of vehicle magnetic moments and the results from use of a fluxgate magnetic sensor to actuate a lighting system from the magnetic fields of passing vehicles is reported. A typical U.S. automobile has a magnetic moment of about 200 A-m²(Ampere-meters²), while for a school bus it is about 2000 A-m². When the vehicle is modeled as an ideal magnetic dipole with a moment of 200 A-m², the predicted results from an analysis of the sensor-vehicle geometry agree closely with observations of the system response to automobiles.     

CMOS integrated silicon pressure sensor

The sensor described includes a four-arm piezoresistance bridge circuit, an amplifier, and a bridge excitation circuit. This circuit is used to stabilize changes in sensitivity due to variations in temperature and supply voltage. The sensor was fabricated using a self-aligned double-poly Si gate p-well CMOS process combined with an electrochemical etch-stop technique using N/SUB 2/H/SUB 4/-H/SUB 2/O anisotropic etchant for the thin-square diaphragm formation. The silicon wafer was electrostatically adhered to a glass plate to minimize thermally induced stress. Less than a /spl plusmn/0.5% sensitivity shift and less than a /spl plusmn/5-mV offset shift were obtained in the 0-70/spl deg/C range, with a 1-V/kg/cm/SUP 2/ pressure sensitivity. By using a novel excitation technique, a sensitivity change of less than /spl plusmn/1.5% under a /spl plusmn/10% supply voltage variation was also achieved.     

Fiber in-line magnetic field sensor based on Mach-Zehnder interferometer integrated with magnetic fluid

In this paper, magnetic fluid (MF), a new type of optical functional nanomaterial with interesting optical characteristics under the external magnetic field, is adopted to form a novel fiber-optic magnetic field sensor. The proposed sensor is based on Mach-Zehnder interferometer (MZI) and has a multimode-singlemode-multimode (MSM) fiber structure. The MSM structure was fabricated by splicing a section of uncoated single mode fiber (SMF) between two short sections of multimode fibers (MMFs) using a fiber fusion splicer. The magnetic field sensing probe was made by inserting the fiber-optic structure in an MF-filled capillary tube. Variations in an external magnetic field is seen to cause changes in the refractive index of MF. This tunable change in the refractive index with magnetic field strengths between 0.6 mT to 21.4 mT produces a shift in the peak position of the wavelength. The shift of the valley wavelength with magnetic field intensity has a good linearity of up to 99.6%. The achieved sensitivity of the proposed magnetic field sensor is 0.123 nm/mT,which is improved by several folds compared with those of most of the other reported MF-based magnetic field sensors. Furthermore, we build the corresponding circuit-based measurement system, and the experimental results show that the voltage change indirectly reflects the change of the external magnetic field strength. Therefore, this provides the potential to fiber-based magnetic field sensing applications.     

A silicon integrated circuit force sensor

A piezoresistive bridge and integrated circuit amplifier can be made in the same silicon cantilever. The purpose of the amplifier is to linearize as well as amplify the output.     

非晶硅集成型色敏元件及其传感器

研究了一种新型的非晶硅ＰＩＮ异质结集成型色敏元件及其传感器的制备工艺和结构，详细讨论了色敏元件的优化设计以及响应特性、暗电流等性能。     

Micro-opto-mechanical vibration sensor integrated on silicon

A new micro-optical vibration sensor has been achieved by combining “integrated optics” and “micromachining” on silicon technologies. The high sensitivity and the wide frequency range have been obtained by using a multimode section in the optical detection circuit. Three prototypes have been installed successfully in an industrial hydroelectric power plant     

Vertically integrated amorphous silicon color sensor arrays

Large-area color sensor arrays based on vertically integrated thin-film sensors were realized. The complete color information of each color pixel is detected at the same position of the sensor array without using optical filters. Sensor arrays consist of amorphous silicon thin-film color sensors integrated on top of amorphous silicon readout transistors. The spectral sensitivity of the sensors is controlled by the applied bias voltage. The operating principle of the color sensor arrays and the influence of device design on spectral sensitivity are described. Furthermore, the image quality of the sensor arrays is analyzed by measurements of the line spread function and the modulation transfer function.     

A CMOS magnetic field sensor

The authors present a novel, fully integrated magnetic field sensor made in the standard, polysilicon-gate CMOS technology. The circuit shows a sensitivity of 1.2 V/T with 10 V supply voltage and 100 /spl mu/A current consumption. The circuit consists of a pair of split-drain MOS transistors in a CMOS-differential amplifier-like configuration.     

Five-contact silicon structure based integrated 3D Hall sensor

A new silicon integrated 3D Hall sensor for high-accuracy magnetic field measurements is suggested and tested. Its unique device design in having only five n/sup +/ contacts allows simultaneous and independent obtaining of the full information about the three components of the magnetic field vector. The device is manufactured through a simple planar process and requires the use of four masks. The lateral dimensions of the sensor are 270/spl times/270 /spl mu/m; the channel magnetosensitivities are S/sub x/=S/sub y/=85 V/AT and S/sub z/=29 V/AT; the nonlinearity and channel cross-sensitivities at B/spl les/1 reach no more than 0.6% and 3-4%, respectively; and the frequency response to AC magnetic field is greater than 30 kHz     

Nonlinear analysis of a CMOS integrated silicon pressure sensor

This paper reports theoretical and experimental results of analysis on the nonlinear characteristics of a CMOS integrated pressure sensor with a square silicon diaphragm. It is shown that nonlinearity is caused by both the large diaphragm deflection and the nonlinear piezoresistance of the resistors. The optimum layout for the piezoresistors to minimize their nonlinearity is also shown. The measured nonlinearity for the fabricated device agrees well quantitatively with the numerically analyzed nonlinearity.     

An ultrasensitive silicon pressure-based microflow sensor

An ultrasensitive silicon pressure-based flowmeter has been developed for use in measuring sub-SCCM gas flow in semiconductor process equipment. The device utilizes a capacitive pressure sensor to measure the pressure drop induced by flow across a micromachined silicon flow channel. The flowmeter is fabricated using a single-sided dissolved-wafer process and requires only six masks. The capacitive pressure sensor uses a thin (2.9 μm) stress-compensated membrane, which enables the sensor to monitor differential pressures as low as 1 mtorr while withstanding overpressures greater than 700 torr. Creep and fatigue change the offset by <0.2% full scale and alter the pressure sensitivity by <0.03 fF/mtorr; the hysteresis observed on all devices has also been <0.2% full scale, where `full scale' is defined to be the pressure required to deflect the membrane half the gap distance. The results reported indicate that it may be possible to extend the pressure range of these devices by an order of magnitude beyond full scale     

An integrated organic passive pixel sensor

We demonstrate an imaging passive pixel sensor circuit consisting of a bottom-gate, top-contact pentacene organic thin-film transistor (OTFT) integrated with a top-illuminated, inverted subphthalocyanine/C₆₀ organic photodetector (OPD). The vacuum-deposited OTFT utilizes parylene as the gate insulator, achieving a drain current ON/OFF ratio of 10⁵. The transistor hole mobility is 0.09 ± 0.02 cm²/V s. The inverted OPD has a dark current of 20 pA at a reverse bias of 1.5 V. By integrating the two components, a 12-bit dynamic range passive pixel sensor is achieved, with an OFF current of 31 ± 5 pA and a pixel readout time of 0.4 ± 0.05 ms, limited by the discharge time of the OTFT channel. The integrated pixel has potential for use in large-scale focal plane array imagers.     

An optical fiber magnetic field sensor based on fiber spherical structure interferometer coated by magnetic fluid

A novel magnetic field sensor based on optical fiber Mach-Zehnder interferometer (MZI) coated by magnetic fluid (MF) is proposed. The MZI consists of two spherical structures formed on standard single mode fiber (SMF). The interference wavelength and the power of the sensing structure are sensitive to the external refractive index (RI). Since RI of the MF is sensitive to the magnetic field, the magnetic field measurement can be realized by detecting the variation of the interference spectrum. Experimental results show that the wavelength and the power of interference dip both increase with the increase of magnetic field intensity.     

An integrated CMOS interface for lambda sensor

Automotive pollution can be reduced by suitably controlling the mixture that is fed to the cylinders. This can be performed by means of a feedback loop including a lambda sond and a processing unit which controls the electronic fuel injectors. This paper describes a CMOS interface which adapts the output signal of a lambda sensor to allow its feeding into the processing unit. It provides a differential to a single-ended conversion with a good common mode rejection, a level shifting around a given reference voltage, and an accurate voltage gain. Both design considerations and the measurements performed on an integrated test structure are presented. The measured variation of the large-signal voltage gain for an input signal of 0 to 1 V is within ±5% when the input common mode voltage ranges from -1 V to 1 V with respect to the negative supply voltage. An output voltage with a precision within ±1 mV is obtained in the presence of an input voltage corresponding to the stochiometric composition of the mixture     

An integrated analog sensor for automatic alignment

Automatic alignment is a computationally intensive task that slows some manufacturing processes that require it. In order to improve alignment speed, we have designed a sensor that combines the imaging operation with the computation of the alignment error. The sensor provides x and y translation error signals when an image of the alignment mark is focused upon it. Photodiodes detect the image, and integrated amplifiers convert the photocurrents into an alignment error signal that is independent of illumination level. Alignment is accomplished in two steps. Coarse alignment is performed by operating as a four quadrant sensor, and fine positioning is achieved using edge detection. Measurements have demonstrated a minimum repeatability of 53 ppm and a maximum bandwidth of 7.5 kHz     

An integrated thermo-capacitive type MOS flow sensor

A prototype of a new thermo-capacitive integrated flow sensor consisting of a floating-gate MOS transistor has been developed. Tantalum pentoxide is the dielectric material between the top (control) gate and the floating-gate. The temperature dependence of the dielectric constant is about 375 ppm/°C. The process flow is compatible with standard MOS process and augmented to include a capacitor module and bulk micromachining. The output voltage change at the flow velocity of 20 m/s is about 26 mV at 57 mW of heater power. The sensitivity in the 0-4 m/s flow velocity region is 4.25 mV(m/s)^-1     

Coiled-fiber sensor for vectorial measurement of magnetic field

New results on the polarization properties of a matched fiber-coil (i.e. one beat length per turn) immersed in a magnetic field are described. It is shown that both components H_y and H_z, perpendicular to the coil axis, can be simultaneously measured. Sensing coils of 1-cm diameter, with multiple turns of fiber, were fabricated. Using 100-turn heads, a sensitivity of 0.01 G was achieved for the vectorial fiber sensor