基于SOPC电导率测量方法研究与实现

传统的电极性传感器对水溶液电导率测量方法忽视了电导池中的电容效应,从而导致了测量精度不高。针对这个问题,提出了基于SOPC电导率测量系统,使用选频电导率测量方法,硬件系统使用SOPC系统,此系统是整个测量系统的核心。系统还设计了方波激励信号发生器、信号放大电路、量程切换电路等硬件电路,不但能够减小极间电阻的影响,同时也能排除引线电容对电导率测量的影响。测试结果表明,此系统电导率相对误差可以达到0.5%以下,并且还具有成本低、抗干扰能力强和在线升级的优点。     

电导率传感器发展概况

电导率传感器广泛应用在工业、科研以及国防等领域,用于测量液体的电导率.介绍了电极型、电感型电导率传感器发展现状,并指出多电极体系、微结构将成为未来电导率传感器发展方向,电导率传感器将与微系统结合,实现电导率测量的自动化、精密化.     

荧光猝灭法溶解氧传感器的研制

为了解决传统在线溶解氧传感器测量过程中需要耗氧,无法满足静止或低流速液体的测量要求.设计了一种以荧光寿命为测量方式的新型荧光法溶解氧传感器.介绍了该传感器测量原理、结构设计、器件的选择和测量电路设计.通过对其进行性能试验,验证了此传感器具有测量精度高、性能稳定等特点,并且此传感器还具有使用寿命长、测量范围广、价格便宜、实现了远距离自动化测量等优点,特别适用于水环境监测及水质污染控制等领域中.仪器通过了江苏省计量科学研究院的验证,各项指标均符合设计要求.     

基于ANSYS有限元法的电导率传感器分析

提出了一种结构简单的新型非接触电导率传感器。从原理出发,采用ANSYS有限元方法,通过建立有限元模型、定义材料属性、网格划分、设置边界条件、加载和求解等,得到了溶液电导率分别与传感器电感和电容之间的关系。利用该传感器对几种已知电导率溶液进行了测试,结果显示其测量的最大相对误差为0.64%,从而证明所提出的传感器测量方法不仅测量精度可行,还提高了测量的冗余度和可靠性,具有很高的商业应用价值。     

作物营养液电导率传感器及其测量系统设计

针对作物营养液电导率的特点,设计了一种基于电磁感应原理与电极组合的电导率传感器及其测量系统.阐述了该组合式电导率传感器的结构与工作原理并选取了传感器最优参数.针对温度对电导率的影响,提出了软件自动温度补偿法,并利用电导率标准液对传感器进行了标定.实验结果表明:该电导率传感器测量的相对误差小于1％,满足作物营养液电导率的测量要求.     

一种海洋MEMS电导率传感器结构优化设计

为提高一种海洋MEMS电导率传感器的测量性能,基于电场基本理论分析了影响传感器测量性能的主要因素,并对 传感器结构进行优化设计, 采用COMSOL软件分别构建和仿真了优化前后传感器测量模型,得出海水电导率在5ｍＳ/ｃｍ~ 70ｍＳ/ｃｍ,激励频率在10ｋＨｚ~ 100ｋＨｚ 范围内,传感器结构优化后比优化前对应的海水测量阻值范围提高了4.39倍,优化后的传感器结构准确度提升至±1.18％,灵敏度提升至1.56ｃｍ－１,且优化前传感器结构准确度与灵敏度的仿真值与相关文献同类型结构传感器实际数据相近,因此本文优化设计贴近实际,参考价值较高。     

机组在线监测平板电容式气隙传感器的研制

研究制作了一种测量水轮发电机定、转子间空气间隙的平板电容式气隙传感器探头,介绍了传感器的测量原理、探头的组成结构及各部分的作用。搭建了模拟实际工作环境的实验平台并进行了性能试验。结果表明：探头的各技术指标均已达到设计要求,且具有测量精度高,响应速度快,工作稳定、可靠,安装方便等特点,特别适用于我国各型发电机组的在线气隙测量。     

基于电导法的原油含水率测量改进方法

基于电导法开展原油含水率测量具有硬件结构简单,系统稳定可靠及测量准确等特点。根据Maxwell模型原理,电导法测量原油含水率需要获知纯水相电导率。然而,开展井下实时含水率测量时,纯水相电导率无法直接测得,直接使用预设的纯水相电导率无法真实得出井下原油的实时含水率。鉴于此,本文根据原油的馏分性质,通过测量不同温度下两组油水,混合相的电导率值并进一步推导得出原油含水率表达式,规避纯水相电导率测试问题及预设纯水相电导率不精确问题,实现对现有原油含水率测量方法的改进。基于ARM Cortex M4处理器及多种传感器测量技术开展了实验研究.实验结果表明,当测量含水率大于90％的油水两相流时,误差可在２％以内。当测量纯水相矿化度在7g/L以内的油水两相流时,含水率误差基本不受矿化度影响。实验结果验证了优化方法理论的有效性,具有实际应用的可行性。     

液体电导率的测量装置设计与制作

测量液体电导率的办法有很多种,其中用两个极板测量液体电导率具有原理简单易懂,测量便捷,容易实现等优点。本文着重对两个平行电极板测量电导率原理及测量中极板极化效应及电容效应进行了论述,并采用等效替代法、交流电桥法设计了三套电路测量生活中液体的电导率,对实验装置进行设计、制作与改进,并对三种生活中的液体取样测量、分析讨论,并对装置的进一步改进提出设想。     

大动态信号的高分辨采集电路设计方法

针对目前感应式电导率传感器存在邻近效应影响导致测量不准确的问题，分析了感应式传感器产生邻近效应的机理。优化设计了一种基于非外部场的感应式电导率传感器探头及信号处理电路，进行了标定与稳定性实验。实验结果表明，非外部场传感器电导率测量准确度小于?0.05 mS/cm。在外界物质邻近电导率测量对比实验中，相较于OST36D型感应式传感器测量偏移达到?0.1~0.7 mS/cm，非外部场传感器的测量偏移小于?0.015 mS/cm，为海水电导率高精度测量提供了一个解决方案。     

基于连接式螺旋体结构的FBG冰层厚度传感器研究

河冰现象是进行水资源开发利用时需要考虑的一个重要现象,冰层厚度检测是冰情状况检测的主要对象。研制了连接式螺旋体结构的光纤Bragg光栅（FBG）温度传感器。基于冰与水温度变点的机理,通过检测冰层与水的温度和传感器纵向分布阵列之间设置的间距得到冰层厚度。该FBG温度传感器使用导热系数较好的毛细紫铜管作为制作螺旋体结构材料。对不同厚度的冰在冰消过程中的厚度检测,实验结果表明：最大测量误差为12mm,最小测量误差为0mm。可通过调节U型管所在斜面和直通管所在平面角度改变各测点之间的间距。     

The cleanroom-free rapid fabrication of a liquid conductivity sensor for surface water quality monitoring

Conductivity is an important issue of water quality detection. Although there are a number of microfluidic liquid conductivity sensors, most of them were difficult to fabricate and required cleanroom facilities, which significantly increased the cost of sensors. Here, we presented a novel liquid conductivity sensor that was built on interdigitated copper electrodes. Microscale sensor electrodes can be fabricated through the modified microfabrication process without any help of cleanroom facilities. In comparison with FEA simulation and commercial conductivity device, measured results showed that the fabricated liquid conductivity sensor was able to measure a wide range of liquids. Considering the ease of fabrication and its low cost, the cleanroom-free fabricated sensors have much potential for water quality monitoring.     

基于冰和水导电特性的新型冰层厚度传感器

包含有离子的水溶液在外施电场作用下是导电的。随着温度的变化,水和冰的导电率也发生变化。基于水和冰的这一导电特性,提出了一种新的冰层厚度传感器结构及其检测方法。这一新型冰层厚度传感器及其检测方法对于在恶劣的检测环境下进行水文检测具有积极的作用。     

电导法原油含水率测量传感器的模型优化与仿真

电导法原油含水率测量是基于阵列电极传感器的一种测量方法,电极系的结构与参数对传感器性能有着重要影响.拟研究电极系传感器结构的优化设计方法,在建立传感器电场分布理论模型的基础上,利用ANSYS有限元软件仿真电极系传感器不同参数下的电场分布,分析电极环宽度、激励电极对间距、测量电极间距等参数对传感器性能的影响.依据仿真结果,确定传感器的优化参数,并对传感器进行了灵敏度的模拟测试,测试结果显示:传感器灵敏度仿真结果与实际测试结果一致性较好;在高含水(大于85%)的油水两相流含水率测试精度可达3%.测试结果验证了传感器理论和仿真分析方法的有效性,为优化设计传感器提供一种有效的方法.     

Development of a bioinspired MEMS based capacitive tactile sensor for a robotic finger

This paper presents the development of a MEMS based capacitive tactile sensor intended to be incorporated into a tactile array as the core element of a biomimetic fingerpad. The use of standard microfabrication technologies in realising the device allowed a cost efficient fabrication involving only a few process steps. A low noise readout electronics system was developed for measuring the sensor response. The performance of both bare and packaged sensors was evaluated by direct probing of individual capacitive sensor units and characterising their response to load–unload indentation cycles.     

采用电容传感器的型砂含水率检测仪

介绍一种采用电容传感器的型砂含水率检测仪,它采用微电容测量技术对信号进行检测,并通过单片机对数据进行处理和控制,测量准确度高于1%,既可作为便携式仪表使用,也可用在生产线上实现混砂加水的自动控制,具有使用方便、测量速度快、性能稳定、控制可靠等优点。     

石墨烯三维微电极生物传感器研究

基于石墨烯优良的导电性和透明性,为改善生物传感器存在透明性不足的缺陷,提出了石墨烯三维微电极传感器的研究.利用SEM,Raman对其形貌进行表征,以及采用电化学测试电极电化学性能,结果表明:研究的石墨烯三维电极生物传感器在透明性和电化学性能方面优于传统微电极生物传感器,为透明生物传感器的制作提供了新思路.     

一种新型的混合平面结构电导率传感器的设计与实现

基于水体-电极系统的机理分析,设计并实现了一种新型的电导率传感器.传感器采用平面矩形线圈与叉指电极混合结构.通过搭建自动化实验平台,采用交流阻抗技术,对研制的传感器进行实测,以获得传感器在不同溶液、不同频率信号激励下的阻抗数据.经过与商用电导率传感器进行数据拟合,找出了阻抗数据与电导率之间的函数关系.实验证明,该电导率传感器是一种灵敏度高、稳定性强的测量工具,其测量精度达到了商用传感器标准,为水溶液电导率的测量提供了一个低成本的解决方案.     

Nozzle condition monitoring in 3D printing

3D printing and particularly fused filament fabrication is widely used for prototyping and fabricating low-cost customized parts. However, current fused filament fabrication 3D printers have limited nozzle condition monitoring techniques to minimize nozzle clogging errors. Nozzle clogging is one of the most significant process errors in current fused filament fabrication 3D printers, and it affects the quality of the prototyped parts in terms of geometry tolerance, surface roughness, and mechanical properties. This paper proposes a nozzle condition monitoring technique in fused filament fabrication 3D printing using a vibration sensor, which is briefly described as follows. First, a bar mount that supports the liquefier in fused filament fabrication extruder was modeled as a beam excited by a system of process forces. The boundary conditions were identified, and the applied forces were analyzed for Direct and Bowden types of fused filament fabrication extruders. Second, a new 3D printer with a fixed extruder and a moving platform was designed and built for conducting nozzle condition monitoring experiments. Third, nozzle clogging was simulated by reducing the nozzle extrusion temperature, which caused partial solidification of the filament around inner walls of the nozzle. Fourth, sets of experiments were performed by measuring the vibrations of a bar mount during extrusion of polylactic acid, acrylonitrile butadiene styrene, and SemiFlex filaments via Direct and Bowden types of fused filament fabrication extruders. Findings of the current study show that nozzle clogging in fused filament fabrication 3D printers can be monitored using an accelerometer sensor by measuring extruder’s bar mount vibrations. The proposed technique can be used efficiently for monitoring nozzle clogging in fused filament fabrication 3D printers as it is based on the fundamental process modeling.     

Development and reliability analysis of micro gas sensor platform on glass substrate

In this paper, technology for a gas sensor platform with borofloat as the substrate material is presented. Comprehensive characterization of the platform, its comparison with silicon and alumina, fabrication yield improvement and a study of reliability of the micro-heater platform have been carried out. Usually, the chips are suspended in air to reduce power consumption. However, the presented technology is a non-MEMS technique and doesn’t require any complex packaging. Borofloat has much lower thermal conductivity in comparison to silicon and alumina, thereby reducing the thermal losses, making it possible to operate the device with low power consumption. The process adapted for the fabrication of the gas sensor platform has lesser complexities and the process cost is reduced compared to conventional gas sensor fabrication, as it does not require thermal oxidation and bulk micromachining. Different substrates (silicon, alumina and glass) have been simulated using COMSOL to depict the benefit of lower thermal conductivity. Micro-heater has also been fabricted on all the three above mentioned substrates and the power consumption is compared. Various reliability analysis have been carried out on the glass based platform such as maximum temperature test, long term ON test and ON–OFF pulse test.