CMOS工艺聚酰亚胺电容型湿度传感器的研究

以正胶光刻和干湿刻蚀方法,结合CMOS工艺制备了聚酰亚胺电容型湿度传感器.研究了硅基、钼-铝栅条状电极湿度传感器的结构及亚胺化温度对其性能的影响.结果表明:相对湿度(RH)为20%～80%发生准静态变化时,该传感器的湿度-电容曲线具有较好的线性度;外界相对湿度在12%和92%间发生阶跃变化时,响应时间约为40 s.     

湿度和频率对湿敏元件电学特性的影响

在印有梳状电极的石英玻璃表面涂覆氧化钛纳米薄膜制备湿敏元件,研究不同湿度、不同频率下的电学特性。结果表明,随着湿度的增大,湿敏元件的电阻值、阻抗值减小,电容增大;当湿度一定时,电阻值、电容值都随频率的增大而减小;工作频率为0.01 kHz、相对湿度高于40%时,具有较好的湿敏特性。实验说明湿敏元件中不仅电子、离子浓度发生变化,材料的极化也发生了变化。     

电容式湿度传感器的设计

为了能够更好解决测量流动蒸汽湿度准确度低、难度大等问题,设计了一种电容式湿度传感器,其为同轴圆筒式多极电容传感器结构,利用电容数字转换技术芯片PCap01进行电容值的检测,通过SPI通信方式将测量结果传输到STM32单片机中进行处理,采用AD421将输出结果转换为标准的4~20 m A信号。实验结果表明,在一定温度下,随着产生湿度的变化,湿度与输出电流呈线性关系,当产生的湿度不变时,电流趋于稳定状态,该设计能够进行湿度的测量。     

一种格栅状上电极的CMOS工艺聚酰亚胺电容型湿度传感器

报道了采用标准CMOS工艺制作的格栅型上电极的电容型湿度传感器,采用高分子材料聚酰亚胺作为感湿介质,铝作为金属电极.对该湿度传感器的器件结构、制作工艺和传感器特性,如灵敏度、湿滞以及响应时间等进行了讨论.测试结果表明,在12%～92%的湿度范围内,电容一相对湿度曲线具有良好的线性度,灵敏度为0.9 pF/RH,响应时间...     

温湿度测控仪

本文介绍的是一款采用两只热敏电阻模仿“干湿球”湿度计原理而制作的温湿度测控仪，干湿球湿度读取相对温度的方法是：首先读取温度传感器是多少湿度，接着读取湿度传感器是多少温度，用温度值减去湿度值，得到它们的差，根据温度传感器的数值和差值，查取表格得到数值后，添加上％号，就是相对湿度值。     

SnO_2-LiZnVO_4系湿敏元件电容特性分析

采用共沉淀法制备SnO2-LiZnVO4系湿敏材料,研究了LiZnVO4的掺杂量对材料湿敏电容的影响。结果表明:LiZnVO4的掺杂量,环境的相对湿度(RH)、测试信号频率对湿敏电容有较大影响。当x(LiZnVO4)为10%时,可使材料具有合适的低湿电容和灵敏度。在100Hz下,当环境的RH从33%上升到93%时,SnO2-LiZnVO4系湿敏材料制备的湿敏元件的电容增量可达起始值的2300%,显示出较高的电容湿度敏感性。湿敏元件的电容响应时间约为54s,恢复时间约为60s。湿滞约为RH6%。     

多点温湿度测量仪的设计

介绍了一种基于1-Wire总线的多点温度、湿度测量仪的设计方案,利用集成湿度传感器HiH3610测得相对湿度,由多功能芯片DS2438测得环境温度和湿度传感器输出的电压值,单片机对DS2438传来的各采集点数据进行处理和显示.该仪器测温范围和精度为:-40℃～80℃,精度:±0.5℃;湿度测量范围:0～100%RH,精度:±2%RH.     

基于单片机的无线温/湿度采集与控制系统

为了研究温/湿度的无线采集与控制,提出基于单片机AT89C52和AT89C2051作为微处理器的无线温/湿度采集与控制系统。由控制器模块、键盘模块、液晶显示模块、无线发射/接收模块、报警模块、空调系统组成。采用温度传感器DS18B20采集温度;采用线性频率输出集成湿度传感器HF3223采集相对湿度;采用键盘对目标温度进行人工设定;采用液晶显示器RT12864和LCD1602显示温度值和湿度值;采用PID算法产生的PWM波来实现对温度的控制;采用无线发射/接收模块实现温度值和湿度值的无线传输和显示。     

一种新型的CMOS集成湿度传感器

利用MEMS技术 ,对一种新型CMOS湿度传感器进行理论分析、模拟以及结果讨论。该湿度传感器采用标准CMOS工艺制造 ,采用梳状铝电极结构、梳状多晶硅加热结构 ,衬底接地 ,感湿介质采用聚酰亚胺 ,利用商业软件Coventor进行模拟绘制出敏感电容与相对湿度的曲线图。接口电路采用开关电容电路 ,输出可测电压信号 ,利用Microsim公司的Pspice模拟电路得到相对湿度与输出电压曲线关系     

一种新型的CMOS集成湿度传感器

利用MEMS技术,对一种新型CMOS湿度传感器进行理论分析、模拟以及结果讨论.该湿度传感器采用标准CMOS工艺制造,采用梳状铝电极结构、梳状多晶硅加热结构,衬底接地,感湿介质采用聚酰亚胺,利用商业软件Coventor进行模拟绘制出敏感电容与相对湿度的曲线图.接口电路采用开关电容电路,输出可测电压信号,利用Microsim公司的Pspice模拟电路得到相对湿度与输出电压曲线关系.     

土壤疏松度对激光等离子体的影响分析

利用Nd:YAG脉冲激光器作为光源,在实验室自然大气环境下诱导产生土壤激光等离子体,测量并分析了土壤疏松度对土壤中铅元素激光诱导击穿光谱特性的影响。实验结果表明,随着对土壤施加压力的变大,谱线强度和等离子体温度先随之增加后变化缓慢,谱线强度的相对标准偏差在压力为1400 N时达最小值。采用内标法和背景修正法对土壤疏松度的影响进行了修正,一定程度上减小了土壤疏松度的影响。     

Soil searching

Low-power radio is primarily associated with remote control, telemetry and short-range communications. It also plays a vital role in the location and maintenance of underground pipes and cables. The various ways in which radio emissions can be used to detect pipes and cables are illustrated by the three operating modes of the CAT (cable avoidance tool), the base product for pipe and cable detection manufactured. by Radiodetection Ltd. In the 'power' mode, the CAT detects signals derived from the mains supply network; in 'Radio' mode, it detects reradiated low-frequency broadcast signals, and, in 'Genny' mode, it detects deliberately imposed signals. The operating frequencies and location depths corresponding to these three modes are indicated. The CAT is a battery-powered, hand-held product with a loudspeaker providing a sound signal to indicate the amplitude of the received radiation     

生物粘泥的清洗

本文主要介绍了生物粘泥清洗原理、清洗方法及一些清洗实例。     

Estimating the Effective Soil Temperature at L-Band as a Function of Soil Properties

To retrieve soil moisture from L-band microwave radiometry, it is necessary to account for the effects of temperature within both vegetation and soil media. To compute the effective soil temperature TG, several simple formulations accounting for soil temperatures at the surface and at depth and surface soil moisture have been developed. However, the effects of the soil physical properties in terms of texture, density, or structure, which all may be important variables in the modeling of TG, have never been investigated. In this paper, several simple formulations of TG at L-band, accounting for or ignoring the effects of soil texture and density, were developed and compared based on a very large simulated data set. The best configurations and parameterizations of these simple formulations were computed and could be directly used for operational applications in future soil moisture retrieval studies. For instance, we showed that the use of the surface temperature in the estimation of TG can be significantly improved by using additional information on the soil temperature at depth (the average error in the estimation of TG decreased from ~ 4 to ~ 1.8 K). On the contrary, almost no improvement was obtained if air temperature was used instead of surface temperature. Also, it is shown that the use of additional information on the soil properties, mainly the soil clay content and density, led to improved results by about 0.2 K in the estimation of TG. The improvement was found to be larger for sandy and dry soils: simplified formulations accounting for soil properties are able to represent the fact that TG is closer to the soil temperature at depth for these soil conditions.     

土壤／橡胶粘附界面土壤表层微形态SEM研究

利用扫描电镜观察了土壤/橡胶粘附系统自然风干后界面处土壤表层微形态,发现土壤表层呈现各种尺度的粗糙结构,微观形态特征与界面所受法向压力的大小有关。文中还对土壤与固体外物表面粘附的机理进行了分析,并依据粘附界面土壤固相形成特征,探讨了土壤粘附界面水膜状态及其对土壤粘附强度的影响。     

Multifrequency Measurements of the Effects of Soil Moisture, Soil Texture, And Surface Roughness

An experiment on remote sensing of soil moisture content was conducted over bare fields with microwave radiometers at the frequencies of 1.4, 5, and 10.7 GHz, during July-September of 1981. Three bare fields with different surface roughnesses and soil textures were prepared for the experiment. Ground-truth acquisition of soil temperatures and moisture contents for 5 layers down to the depths of 15 cm was made concurrently with radiometric measurements. The experimental results show that the effect of surface roughness is to increase the soil's brightness temperature and to reduce the slope of regression between brightness temperature and moisture content. The slopes of regression for soils with different textures are found to be comparable and the effect of soil texture is reflected in the difference of regression line intercepts at brightness-temperature axis. The result is consistent with laboratory measurement of soil's dielectric permittivity. Measurements on wet smooth bare fields give lower brightness temperatures at 5 than at 1.4 GHz. This phenomenon is not expected from current radiative transfer theory, using laboratory measurements of the relationship between dielectric permittivity and moisture content for different soil-water mixtures at frequencies of <5 GHz.     

分层土壤后向散射及其在深层土壤湿度探测中的应用

该文定量地分析了频率、入射角、土壤介电常数等主要因素对电磁波穿透性能的影响。计算了分层土壤后向散射系数与地表参数,介电常数,系统工作频率,极化方式,入射角的关系,并从理论上得到验证,为深层土壤湿度反演提供了一个比较合理的模型。文中结论对低频段(0.1-1GHz)合成孔径雷达系统设计及深层土壤湿度反演具有实际应用价值。     

L-Band Radar Sensing of Soil Moisture

The objectives of this experiment were to assess the performance of an L-band, 25-cm wavelength imaging synthetic aperture radar (SAR) for soil moisture determination, and to study the temporal variability of radar returns from a number of agricultural fields. A series of three overflights was accomplished during March 1977 over an agricultural test site in Kern County, CA. Soil moisture samples were collected from bare fields at nine sites at depths of 0-2, 2-5, 5-15, and 15-30 cm. These gravimetric measurements were converted to percent of field capacity for correlation to the radar return signal. The initial signal film was optically correlated and scanned to produce image data numbers. These numbers were then converted to relative return power by linear interpolation of the noise power wedge which was introduced in 5-dB steps into the original signal film before and after each data run. Results of correlations between the relative return power and percent of field capacity (%FC) demonstrate that the relative return power from this imaging radar system is responsive to the amount of soil moisture in bare fields. The signal returned from dry (15%FC) and wet (130%FC) fields where furrowing is parallel to the radar beam differs by about 15 dB. Problems remain to be resolved before this technique can be operationally employed. First, adequate calibration of the radar system is required to insure comparability of data both from area to area within a single flight and between different flights.     

Soil moisture retrieval from AMSR-E

The Advanced Microwave Scanning Radiometer (AMSR-E) on the Earth Observing System (EOS) Aqua satellite was launched on May 4, 2002. The AMSR-E instrument provides a potentially improved soil moisture sensing capability over previous spaceborne radiometers such as the Scanning Multichannel Microwave Radiometer and Special Sensor Microwave/Imager due to its combination of low frequency and higher spatial resolution (approximately 60 km at 6.9 GHz). The AMSR-E soil moisture retrieval approach and its implementation are described in this paper. A postlaunch validation program is in progress that will provide evaluations of the retrieved soil moisture and enable improved hydrologic applications of the data. Key aspects of the validation program include assessments of the effects on retrieved soil moisture of variability in vegetation water content, surface temperature, and spatial heterogeneity. Examples of AMSR-E brightness temperature observations over land are shown from the first few months of instrument operation, indicating general features of global vegetation and soil moisture variability. The AMSR-E sensor calibration and extent of radio frequency interference are currently being assessed, to be followed by quantitative assessments of the soil moisture retrievals.