Low-cost sensor to detect overtaking based on optical flow

The automotive industry invests substantial amounts of money in driver-security and driver-assistance systems. We propose an overtaking detection system based on visual motion cues that combines feature extraction, optical flow, solid-objects segmentation and geometry filtering, working with a low-cost compact architecture based on one focal plane and an on-chip embedded processor. The processing is divided into two stages: firstly analog processing on the focal plane processor dedicated to image conditioning and relevant image-structure selection, and secondly, vehicle tracking and warning-signal generation by optical flow, using a simple digital microcontroller. Our model can detect an approaching vehicle (multiple-lane overtaking scenarios) and warn the driver about the risk of changing lanes. Thanks to the use of tightly coupled analog and digital processors, the system is able to perform this complex task in real time with very constrained computing resources. The proposed method has been validated with a sequence of more than 15,000 frames (90 overtaking maneuvers) and is effective under different traffic situations, as well as weather and illumination conditions.     

Low-cost fiber-optic waveguide sensor for the colorimetric detection of ammonia

We present the development and characterization of a low-cost fiber-optic colorimetric gas sensor for ammonia combined with the electronic circuitry for measurement control and RFID communication. The gas sensor detects ammonia using a 300?μm polyolefin fiber coated with a gas-sensitive polymer film. The spectral and time-dependent sensitivity of various polymer films was tested in transmission measurements at λ?=?590?nm. A prototype of the gas sensor was tested under realistic measurement conditions, i.e. battery-driven and in a completely autonomous mode. The sensor system showed good sensitivity to the ammonia concentrations and response times in the order of minutes. The achievable power consumption was below 100?μW. Bromophenol blue-based films showed a strong reaction to ammonia, with saturation concentrations around 1,000?ppm and response times of about 15?s to 100?ppm. The colorimetric reaction was simulated using a simple kinetic model which was in good agreement with the experimental results.     

光纤压力传感器

提出一种记数法布里珀罗(F-P)腔的干涉条纹的光纤压力传感器,可以用于易燃、易爆的环境。阐述了它的设计原理、参数的设置和误差的讨论及改进。试验结果表明:光纤F-P腔脉冲计数压力传感器结构简单、成本低、抗干扰能力强,具有很大的测量范围和分辨力,分别达到10m和0.02%。     

Low-cost colorimetric sensor for the quantitative detection of gaseous hydrogen sulfide

A simple, rapid and low-cost method for differentiating a wide range of concentrations of gaseous hydrogen sulfide (H₂S) is described. A large dynamic range (50 ppb to 50 ppm) was successfully classified at ambient temperature using a colorimetric sensor array comprised of chemoresponsive dyes coupled to a commercially available 8-bit flatbed scanner. Principle component analysis of the composite magnitude and kinetics of color change for the array of dye spots over the entire dynamic range resulted in 100% classification. This was achieved by including chemoresponsive dyes which reacted specifically with H₂S at different detection thresholds.     

Polysilicon nanofilm pressure sensor

Utilizing 80 nm polysilicon nanofilm as piezoresistors, a pressure sensor with high performance is developed. The complete fabrication process is described. The pressure properties of the sensor were measured at the temperature from 0 to 200 °C. For 0.6 MPa full scale pressure, the sensitivity is 23.00 mV/V/MPa at 0 °C and 18.27 mV/V/MPa at 200 °C, the temperature coefficient of sensitivity (TCS) is about −0.098%/ °C without any compensation. The temperature coefficient of offset (TCO) is about −0.017%/ °C. Because of the good piezoresistive and temperature characteristics of polysilicon nanofilm, the pressure sensor demonstrates a better performance.     

PVDF土压力传感器

为适应土中动态压力测试的需要,研制了PVDF土压力传感器;介绍了传感器的测压工作原理及传感器的结构,并给出了传感器在某爆炸冲击试验中的应用情况;试验表明,PVDF压力传感器适合于爆炸荷载作用下土中压力测量。     

Polycrystalline diamond pressure sensor

The piezoresistance and other characteristics of boron doped polycrystalline diamond films (PDF's) were determined by analyzing free-standing films that had been formed on silicon. These structures were adhered to a dielectric substrate, and from bending stresses a gauge factor was estimated. Subsequently, a monolithic all-diamond pressure sensor was designed and fabricated, whereby doped diamond resistors reside on a dielectric diamond substrate diaphragm. The process and piezoresistance behavior of their structure is described     

新型波纹管压力传感器

通过对弹性敏感元件的研究 ,设计制造了带有充填物的波纹管 ,解决了薄壁波纹管不能承受高压的难题 ,又保持了较高的灵敏度。代替了常规的压力传感器中的橡皮膜和弹簧 ,重新制作了新型的压力传感器并在 1994年获得了国家专利证书     

High-temperature ceramic pressure sensor

A pressure microsensor for working at high temperature has been developed. The device consists of a tantalum nitride thin film, patterned on a Wheatstone bridge configuration, sputter-deposited onto thermally oxidized silicon wafers with an aluminium interconnection layer and a silicon dioxide passivation. The microsensors present a low temperature coefficient of resistance and good long-term stability. The sensitivity is 0.15 mV (V bar)⁻¹ with low sensitivity drift and low combined non-linearity and hysteresis in the pressure range 0–10 bar.     

On-board phthalocyanine gas sensor microsystem dedicated to the monitoring of oxidizing gases level in passenger compartments

The monitoring of in-vehicle pollutant concentrations by means of an on-board molecular semiconductor gas sensor microsystem is described in this paper. The main objective is to measure in real time with a high level of accuracy the variations of oxidizing gases concentration in bus passenger compartments to inform travelers or commuters and to evaluate the assessment of bus drivers’ exposure. A self-contained gas sensor microsystem of which the sensitive element is constituted by a thin layer of copper phthalocyanine has been developed, validated at laboratory under controlled experimental conditions and then implemented in a bus of the urban network of Clermont-Ferrand, France. Preliminary in-car measurements realized with commercial analyzers show that nitrogen dioxide is the major oxidizing gas present on urban roads and so is considered as the target gas in this study. Tests realized under artificially polluted atmosphere show the high performances obtained with our microsystem, such as high resolution, low threshold, good reproducibility, satisfying concentration range and real time detection. The calibration curve has been determined at laboratory by experiments made under low NO₂ concentrations in the range of those measured in urban atmosphere. The relation between sensor microsystem response and gas concentration is established with accuracy. The validation of our microsystem is illustrated by measurements realized under real conditions, i.e., in an urban bus. It shows that NO₂ concentration variations are mainly correlated with the nature of roads and that rates of pollutant measured in traffic are always greater than those measured by the nearest stations of the air quality control network.     

硅基光波导压力传感器

硅基光波导压力传感器由于具有灵敏度高、耐高温、抗电磁场干扰能力强、微型等优点 ,特别适合于在特殊环境中的应用。简要介绍了全反射光波导和抗共振反射光波导压力传感器的结构特点、工作原理及其研究现状。     

膜盒式压力传感器的应用

介绍了远距离冷气压力表传感器和指示器的基本构造及二者的电路连接关系 ,利用简单的电路实现了远距离冷气压力的测量。详细论述了远距离冷气压力表的测压原理。     

轮胎气压传感器设计

设计了一种霍尔式轮胎气压传感器，用于为汽车轮胎气压自动监测和报警系统提供轮胎气压输入信号。该传感器由机械式压力传递机构和磁性与磁敏元件组成，能以非接触方式将轮胎气压信号传至车体。介绍了传感器的结构特点、工作原理和主要部件的设计计算方法。     

A wireless microsystem for the remote sensing of pressure, temperature, and relative humidity

This work presents a microsystem that utilizes inductive power and data transfer through a backscatter-modulated carrier and a transducer interface that monitors its environment through embedded capacitive transducers. Formed on a single chip, transducers for temperature, pressure, and relative humidity are realized using a silicon-on-glass process that combines anodic bonding and a silicon-gold eutectic to realize vacuum-sealed cavities with low-impedance (6 /spl Omega/) electrical feedthroughs. Temperature is sensed capacitively using a row of Si/Au bimorph beams that produce a sensitivity of 15 fF//spl deg/C from 20 to 100/spl deg/C. The absolute pressure sensors have a sensitivity of 15 fF/torr and a range from 500 to 1200 torr, while the relative humidity sensor responds with 39 fF/%RH from 20 to 95%RH. A relaxation oscillator implements low-power capacitance-to-frequency conversion on a second chip with a sensitivity of 750 Hz/pF at 10 kHz, forming a 341 /spl mu/W transducer interface. The system is remotely powered by a 3-MHz carrier and has a volume of 32 mm/sup 3/, including the hybrid antenna wound around the perimeter of the system.     

Micro-machining processes for microsystem technology

By means of experiments it could determined that micro-machining processes as grinding, drilling and milling are a good addition to the established production technologies in micro technology. To machine hard and brittle materials grinding with diamond tools is well suitable, but the kinematics of the grinding process, as well as the process strategy has a significant influence on the machined surface quality and the chipping of the edges. The study of micro-machining processes showed, that micro cutting processes are not just a miniaturisation of the conventional cutting technology. The reduced tool stiffness of micro drills caused by the changes of geometry requires an adjustment of the complete drilling processes. Sharp cutting edges are an essential requirement for the fabrication of very small structures. So, using single edged micro milling cutters made of diamond significant smaller structures could be made compared to using conventional milling cutters made of tungsten carbide. Furthermore, acoustic emission sensors proved to be suitable for detecting the tool position after a change of the tool with a high accuracy.     

Ultra-low pressure sensor for neonatal resuscitator

A Venturi-type flow sensor has been designed and fabricated for neonatal respiratory assistance to control airway pressure and tidal volume. As the low flow range and sensing principle require the measurement of correspondingly very low pressures, a very responsive sensor, based on a polymer membrane acting onto a piezoresistive cantilever force sensor based on low-temperature co-fired ceramic (LTCC), was developed. This paper details the 3D modelling, manufacture, assembly and characterisation of the sensor. Compared to expensive and fragile MEMS-based devices, this sensor, based on LTCC, thick-film technology and polymer parts, provides an accurate and robust, yet low-cost alternative.     

石英晶体谐振式绝对压力传感器研制

介绍了一体化石英谐振式压力传感器的研制,采用石英晶体材料制做弹性膜片,用音叉式石英力敏谐振器检测压力,减少了传感器的体积,降低了制造工艺难度。研制的传感器量程为0~120 kPa,中心频率为(40±4)kHz,精度为0.05%。