Temperature sensor based on composite film of vanadium complex (VO2(3-fl)) and CNT

A vanadium complex (VO₂(3-fl)) and CNT composite film based temperature sensor is reported in this study. Surface-type silver electrodes were deposited on the glass substrates. A thin film of VO₂(3-fl) and CNT composite was coated as a temperature-sensing material on the top of the pre-patterned Ag electrodes. The temperature-sensing principle of the sensor was based on the conductivity change of the coated sensing element upon heating or cooling processes. DC and AC (100 Hz) resistances of the temperature sensor decreased quasi-linearly with increasing the temperature in the range of 25-80 ℃. The overall resistance of the sensor decreases by 1.8-2.1 and 1.9-2.0 times at DC and AC voltage, respectively. The resistance temperature coefficients of the sensor were in the range of -(0.9-1.3)% and -(1.1-1.3)% at DC and AC voltage, respectively. The properties of the sensor studied in this work, make it beneficial to be used in the instruments for environmental monitoring of temperature.     

Novel capacitance-type humidity sensor based on multi-wall carbon nanotube/SiO2 composite films

A novel capacitance-type relative humidity (RH) sensor based on multi-wall carbon nanotubc/SiO2 (MWCNTs/SiO2) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiO2 composite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold (1.842wt％),the sensor capacitance increases obviously with increasing MWCNTs.The water condensed in the MWCNTs/SiO2 layer can lower the percolation threshold and increase the sensor capacitance.The sensor with MWCNT concentration of 1 wt％ has the best properties.The sensor has a humidity sensitivity of about 673 pF/％ RH and a linearity correlation of 0.98428.The response time of the sensor to RH is about 40 s and the recovery time is about 2 s.     

Surface-type humidity sensor based on cellulose-PEPC for telemetry systems

In this study, Au/Cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole (PEPC) blend thin films. Blend of 2 wt.% of each cellulose and PEPC in benzol were used for the deposition of humidity sensing films. Blend films were deposited on glass substrates with preliminary deposited surface-type gold electrodes. Films of different thicknesses of cellulose and PEPC composite were deposited by drop-casting technique. A change in electrical resistance and capacitance of the fabricated devices were observed with the increase of relative humidity in the range of 0−95% RH. It was observed that the capacitances of the sensors increase, while their resistances decrease with increasing of the relative humidity. The sensors were connected to op-amp square wave oscillators. It was observed that with increase of relative humidity, the oscillator’s frequencies were also increased in the range of 4.2−12.0 kHz for 65 μm thick film sample and 4.1−9.0 kHz for 88 μm thick film sample and for 210 μm sample, the oscillator frequency changed in the range of 4.2−9.0 kHz. Effects of film thickness on the oscillator’s frequency with respect to humidity were also investigated. This polymer humidity sensor controlled oscillator can be used for short-range and long-range remote systems at environmental monitoring and assessment of the humidity level.     

基于纳米多孔薄膜的对称平面光波导湿度传感器

通过在对称平面玻璃光波导上下表面各制备一层纳米多孔TiO2薄膜,形成了一种简单新颖的光学湿度传感器。其原理为,导波光在平面对称光波导中的传播损失依赖于纳米多孔Ti02薄膜的平均折射率,后者依赖于薄膜内部的水分子吸附量,而薄膜的水分子吸附量随着周围相对湿度的变化而变化,通过实时测量导波光传播损失的变化就能够感知外围的相对...     

Surface-type humidity sensor based on cellulose-PEPC for telemetry systems

Au/cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole(PEPC) blend thin films.A blend of 2wt%of each cellulose and PEPC in benzol was used for the deposition of humidity sensing films.Blend films were deposited on glass substrates with preliminary deposited surface-type gold electrodes.Films of different thicknesses of cellulose and PEPC composite were deposited by drop-casting technique.A change in electrical resistance and capacitance of the fabricated devices was observed by increasing the relative humidity in the range of 0-95%RH.It was observed that the capacitances of the sensors increase,while their resistances decrease with increasing the relative humidity.The sensors were connected to op-amp square wave oscillators.It was observed that with increasing the relative humidity,the oscillator’s frequencies were also increased in the range of 4.2-12.0 kHz for 65μm thick film sample,4.1-9.0 kHz for 88μm thick film sample,and 4.2-9.0 kHz for 210μm sample.Effects of film thickness on the oscillator’s frequency with respect to humidity were also investigated.This polymer humidity sensor controlled oscillator can be used for short-range and long-range remote systems at environmental monitoring and assessment of the humidity level.     

基于多壁碳纳米管/SiO2复合材料检测的新型电容型碳纳米管湿度传感器

A novel capacitance-type relative humidity(RH) sensor based on multi-wall carbon nanotube/SiO_2 (MWCNTs/SiO_2) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiO_2 composite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold(1.842wt%),the sensor capacitance increases obviously with i...     

Optical transmission in thin films of vanadium compounds

Thin films of five vanadium compounds/composite： （1） VO2（3-fl） （3-fl = 3-Hydroxyflavone）, （2） VO（pbd）： （pbd = 1-Phenyl-l, 3-butadione）, （3） VO（dbm）2 （dbm = Dibenzoylmethane）, （4） VPc （Vanadyl Phthalocyanine） and （5） V2O5-PEPC （V2O5- poly-N-epoxypropylcarbazole composite）, were deposited by the dropcasting method from the solution in benzene. The transmittance-irradiance relationships were investigated and the transmission in the visible spectrum and optical images were obtained as well. It was found that the transmittance of the VO2（3-fl）, VO（pbd）2, VO（dbm）2 and VPc, was practically independent of the irradiance; whereas the transmittance of V2O5-PEPC decreased by 4% for thin and 9% for thick films with an increase of the irradiance.     

不同升温热处理方式二氧化钒薄膜的制备与光学相变性能

采用双离子束溅射方法制备氧化钒薄膜,分别利用常规和快速两种升温方式对氧化钒薄膜进行热处理,利用傅里叶变换红外光谱技术对热处理后氧化钒薄膜的变温光学透射性能进行测试,并对5μm波长处透过率随温度的变化曲线进行相变特性分析.实验结果表明,经过常规和快速升温热处理后均获得了二氧化钒薄膜;快速升温热处理后得到的薄膜中二氧化钒晶粒较小,尺寸分布均匀;而常规升温热处理后的二氧化钒薄膜中晶粒尺寸分布较宽、常规和快速升温热处理后,氧化钒薄膜的光透过率均存在可逆突变特性,变化幅度均超过60%.相变性能分析结果表明,快速升温热处理获得的二氧化钒薄膜相变持续的温度宽度较大,光学相变温度为63.74℃,高于常规升温热处理的60.31℃.     

测辐射热计的微桥研制和Vox膜成膜研究

介绍了测辐射热汁的工作原理、器件结构的几何形状和研制状况,叙述了测辐射热计材料的特性及制备技术.     

基于琼脂薄膜的微型端面光纤F-P湿度传感器

提出了一种基于琼脂薄膜的微型法布里-珀罗(F abry-Perot,F-P)光纤湿度传感器。传感器通过将标准单模光纤插入空 芯玻璃管并在玻璃管端面浸涂琼脂薄膜形成双F-P结构 。当环境相对湿度变化时,琼脂薄膜的体积和 折射率发生改变,从而引起干涉光发生波长偏移。搭建了湿度传感实验系统,对传感器的湿 度传感特性进行了表征,在50%RH—80%RH的相 对湿度范围内实现了高达1.232 nm/%RH的相对湿度测量灵敏度。该传感器尺寸紧凑、成本低、具有较好的线 性 灵敏度,且制备方式简单。     

基于LabVIEW的湿敏元件性能测试分析系统

为了克服传统的传感器特性测试仪功能单一、专用性强的缺点,利用GPIB卡组建由ZL5型智能LCR测试仪与计算机构成的湿敏元件性能测试系统,并基于LabVIEW开发出系统控制软件。根据存储文件方式的不同,采用不同的图形分析方法。通过将其应用于氧化钛基薄膜的湿敏特性研究实验,结果表明该系统能够方便、直观地分析湿敏元件的性能。     

长周期光纤湿度传感器特性的研究

介绍了一种可测量相对湿度的长周期光纤光栅传感器,其原理是在光纤包层外涂上聚乙烯醇(PVA)薄膜,外界湿度变化引起PVA薄膜折射率的变化,从而引起长周期光纤光栅谐振波长的改变,通过测量光纤湿度传感器长周期光纤光栅透射光谱就能得到周围环境的相对湿度.实验证明,涂覆PVA薄膜的长周期光纤光栅湿度传感器具有良好的稳定性和一系列突出优点.     

CMOS电容式湿度传感器特性研究

提出了一种CMOS电容式湿度传感器特性研究方案.研究所用的微电容湿度传感器由标准CMOS工艺结合MEMS 后处理技术加工而成.为了测试湿度传感器的响应时间,设计了一种响应时间测试装置.测试结果表明,该电容式湿度传感 器在相对湿度25％～95％的范围内具有较好的线性度;其回滞在75％RH时达到最大,为2％ RH;该传感器...     

高分子电容型湿度传感器研制

随着工业的快速发展,对温度检测和控制日益严格,温度传感器已无法跟上人们的需求,通过优化湿度传感器的表面结构和对感湿材料微孔设计提高了感湿特性,增强感湿材料的感湿特性,并对湿度传感器测量电路进行改进,提高微小电容测量,设计湿度测试系统。通过实验验证了改进后的湿度传感器测量效果更优越。     

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     

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.     

Optical absorption behaviour of vanadium pentoxide thin films

Thin films of vanadium pentoxide have been prepared by the electron beam evaporation technique over a wide range of substrate temperatures. Spectrophotometric investigations have been made on these films in the wavelength range 350–1500 nm to determine the nature of the optically induced transition and the optical band gap. A better fit for the direct forbidden transition than for the indirect allowed transition is observed in all the films. The optical band gap is found to decrease with increasing substrate temperature and the subsequent appearance of a broadband absorption at about 1000 nm is attributed to the oxygen vacancies in the films. The effect of heat treatment in vacuum and oxygen ambient on the optical properties of these films is also reported. © 1997 John Wiley & Sons, Ltd.     

基于个域网的无线温湿度传感器设计及医学实验室应用

设计和实现一种基于个域网技术的温湿度监测系统。结合无线传感器的网络技术,采用ATmega16L单片机作为控制核心,以及可以支持最新版的ZigBee 2007/Pro 协议栈。通过该系统应用于实验室后达到了低功耗、低成本、可扩充性好、易于维护的预期效果,得出基于个域网的无线温湿度传感器的设计满足了低成本、低功耗要求的结论。     

基于C8051F410的网络温湿度传感器的设计

为了对环境的温湿度数据进行实时采集并通过网络监控。本文以8位单片机C8051F410为核心,利用其自带SH总线功能和网卡芯片ENC28J60通信。在单片机内部完成轻量级TCPhP协议栈UIP协议的移植,最终实现了通过浏览器即可访问传感器节点温湿度信息。传感器部分采用单总线接口的工业级AM2305温湿度传感器。系统具有很强可扩展性。可满足当前物联网温湿度采集系统的大部分应用。     

DHT11数字式温湿度传感器的应用性研究

基于DHT11温湿度传感器具有测量精度高、响应速度快、抗干扰能力强等优点。通过介绍DHT11数字式温湿度传感器的内部结构、工作原理、驱动方式及DHT11与微控制器LPC2138的接口电路、指令时序和温湿度测量过程,并通过该传感器构成的节点在一段时间内对大棚蔬菜内部环境进行际测试试验,试验结果表明,由该传感器构成的节点具有体积小巧、操作简单、功耗较低的优点,更加适用于目前对于温湿度现场检测的需求。