Study on optical fiber multi-parameter sensor

Based on the principle of fiber Bragg grating detection,an optical fiber sensor for detecting wind speed and temperature and humidity in underground space was designed.The designed optical fiber wind speed sensor was based on the thermal flow detection method,which has high sensitivity to low wind speed.For the speed rising from 0 to 0.5 m/s,the wavelength variation is about 800 pm.For the demodulator with sensitivity of 1 pm,the speed resolution is 0.7 mm/s.Fiber optic humidity sensor was fabricated by uniform surface coating of FBG element in polyimide solution,and detection sensitivity of 4.2 pm/% RH was achieved with accuracy less than ± 3% RH.     

基于倾斜光纤光栅的相对湿度传感器

提出了一种基于倾斜光纤光栅(TFBG)的包层上覆盖着聚乙烯醇(PVA)的空气相对湿度传感器,成功实现了对相对湿度在20～98%RH范围内的监测。研究发现,TFBG的透射功率在20～74%RH和74～98%RH2个相对湿度区域内分别呈现不同的线性变化,敏感度分别为2.52 dBm/%RH和14.95 dBm/%RH,并且在高湿度区有更高的敏感性。     

Relative Humidity Sensor Based on Tilted Fiber Bragg Grating With Polyvinyl Alcohol Coating

A relative humidity (RH) sensor based on tilted fiber Bragg grating (TFBG) is proposed by utilizing polyvinyl alcohol (PVA) as the sensitive cladding film. RH increasing in the PVA coating will result in reduction of refractive index. Due to the TFBG's sensitivity to ambient refractive index, the spectral properties of PVA-coated TFBG are modified under exposure to different ambient humidity levels ranging from 20% to 98% RH. The transmission power of TFBG has different linear behaviors for two different humidity ranges (20%–74% RH and 74%–98% RH), and the sensitivity for each humidity range reaches as high as 2.52 and 14.947 dBm/%RH, respectively. Combining the advantages of optical fiber grating and PVA as a smart material, this design involves simple configuration, low cost, compactness, a small degree of hysteresis, stability, and wide dynamic sensing range as well. Therefore, the sensor could be applied in real-time RH monitoring for normal as well as extremely humid environments.      

基于光纤环镜的温度不敏感相对湿度传感器

提出了一种基于两段相同长度的保偏光纤环镜的温度不敏感相对湿度传感器,其中一段保偏光纤经高浓度的氢氟酸腐蚀后覆以一层湿敏材料聚乙烯醇薄膜用于获得空气的相对湿度,另一段保偏光纤则对传感器的温度进行补偿。该传感器成功实现了对周围环境相对湿度(RH)20%~80%范围内的测量,同时不受外界环境温度的影响。实验表明,该传感器所得数据呈现出良好的线性关系,获得的湿度灵敏度为0.98 nm/%(RH),温度所带来的影响仅为0.0072 nm/℃,达到了消除温度影响的目的。     

基于PI湿敏薄膜的分布式光纤Bragg光栅湿度传感器

研究了基于聚酰亚胺（PI）湿敏薄膜的分布式光纤Bragg光栅（FBG）湿度传感器。传感器利用PI薄膜湿膨胀效应,将湿应变作用于Bragg栅区,从而改变光纤FBG湿度传感器中心波长的原理,实现了对26-98％RH范围内环境相对湿度的监测。通过改进PI湿敏薄膜的制备及涂覆工艺,有效提高了FBG湿度传感器性能,并采取了相应温...     

复合钒钛酸干凝胶薄膜的湿敏特性研究

采用sol-gel法制备了复合钒钛酸干凝胶(H2V10Ti2O30-y·nH2O)薄膜,并对其湿敏特性进行了研究。结果表明:该薄膜为层状结构。用此薄膜制备的湿敏元件,在RH为11%～95%的范围内,感湿特性曲线线性好,其响应、恢复时间分别为5s和20s,湿滞为RH2%,感湿温度系数为RH0.45%/℃,并具有良好的稳定性。H2V10Ti2O30-y·nH2O干凝胶薄膜湿敏元件的灵敏度和湿滞均优于复合钒酸(H2V12O31-y·nH2O)干凝胶薄膜湿敏元件。     

用于PEMFC的FBG湿度传感器的制作及性能研究

研究了以聚酰亚胺为湿敏材料的光纤Bragg光栅(FBG)湿度传感器并用其对质子交换膜燃料电池(PEMFC)停机过程中内部湿度进行了实时监测。传感器利用聚酰亚胺的湿膨胀效应,实现 了对24.7%－ 98%RH范围内相对湿度的监测。采用腐蚀光纤包层的方法减小光纤包 层直径,实验结果表明,该方法能在 不影响FBG相对湿度传感器灵敏度的情况下,提高对外界环境相对湿 度变化的响应速度。所 研制的FBG 相对湿度传感器灵敏度能达到3.8 pm/RH,线性度达到99.85%,最大回程误差不超过9pm,当环境相对湿 度从50%突变到85%时,经过腐蚀处理后的FBG 相对湿度响应时间仅为15.4 s。将该FBG湿度传感器布置 于PEMFC内部进行停机过程中湿度的实时监测,实验结果表明,所制作的FBG湿度传感器能够 准确地反映PEMFC停机吹扫过程中内部湿度的变化。     

飞秒激光制备光纤U形微结构应用于折射率传感

为了实现低成本、高精度的折射率测量,采用飞秒激光微加工技术,制备出基于U形微结构的多模光纤液体折射率传感器。研究了传感器的通光功率变化值与U形槽深度以及U形槽内液体折射率的关系,同时探究了在相同光损耗情况下不同烧蚀长度对灵敏度的影响,并使用射线理论和模式理论对传感机理进行了分析。结果表明,该传感器在折射率1.3331~1.3731范围内具有良好的线性响应,且可以做到5700μW/RIU的灵敏度;同时在10dB损耗情况下20μm烧蚀长度具有较好的灵敏度。该传感器具有结构简单、容易制备、灵敏度高和低成本等优点,在化学、生物、医学、环境监测等方面有广泛的应用前景。     

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%。     

准确检测偏二氯乙烯的红外光纤倏逝波传感器

利用中红外光纤构建了一种在线准确检测偏二氯乙烯的红外光纤倏逝波传感器,该传感器由U形中红外光纤传感探头、偏二氯乙烯选择性敏感膜和超疏水膜构成.四氟乙烯敏感膜涂覆在U形区表面,超疏水膜涂覆在偏二氯乙烯敏感膜表面.U形传感器可增强光纤表面倏逝波强度,从而提高传感器的灵敏度.敏感膜可实现对水体中偏二氯乙烯的选择性测量,提高传...     

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...     

A new thin-film humidity microsensor

A new humidity microsensor using barium titanate thin film in the metal-insulator-semiconductor (MIS) structure has been developed. These devices have capacitances sensitive to changes of relative humidity (RH), with a sensitivity of 300-percent change of capacitance corresponding to a humidity change from 27 to 90-percent RH at a testing frequency Of 1 MHz. The capacitance-voltage (CV) and current-voltage (I-V) characteristics for various relative humidities are presented. Temperature and frequency effects on sensor performance are also presented.     

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.     

纺织基底无芯片RFID 湿度传感器

研制了一种无湿敏材料的纺织基底无芯片RFID 湿度传感器用于检测环境湿度。通过射频仿真软件 HFSS,获得谐振频率在2. 45 GHz 具有较高品质因数的纺织基底谐振器模型,对以谐振频率偏移量作为灵敏度指标 的检测原理进行了仿真。利用丝网印刷工艺和刻绘工艺分别在不同类型纺织物上制作了无芯片RFID 湿度传感器, 系统研究了制作工艺、纺织品类型和厚度对传感器湿敏特性的影响。结果表明,0. 5 mm 厚度下不同基底类型湿度传 感器的灵敏度由高至低依次为:棉基底、亚麻基底、聚酯纤维基底,恢复特性呈相反顺序,其中棉基底传感器在高湿 范围内平均灵敏度达3. 8 MHz/ %RH,聚酯纤维基底传感器恢复度达86%;相同类型的棉纺织基底下基底厚度越大, 平均湿度灵敏度越高,恢复特性越差。传感器稳定性测试表明传感器具有较好的中长期稳定性。对纺织基底湿度 传感器的感湿机理进行了分析,纺织纤维中的亲水基团与水分子间形成氢键,改变了基底的介电参数,传感器的湿 敏特性与组成纺织品的纤维成分、纤维细度、编织方式有关。     

一种新型CMOS兼容湿度传感器

给出了与CMOS工艺兼容的一种新型梳齿状湿度传感器的结构、工艺流程及其测试结果.利用Coventor软件对这种新型结构进行了理论分析,对制备出的湿度传感器的性能如灵敏度、滞回特性、重复性、响应时间等进行了测试并讨论.结果表明文中提出的CMOS湿度传感器工艺简单、响应时间快、成本低、灵敏度高,有望在实际中得到应用.     

Nonadiabatic tapered single-mode fiber coated with humidity sensitive nanofilms

A new humidity sensor has been developed by coating a tapered single-mode standard communications fiber with a humidity sensitive nanofilm using the electrostatic self-assembled (ESA) monolayer technique. Power changes up to 20 dB have been recorded during the coating process. In order to take advantage of both the potential sensitivity of the tapered fiber and the precise thickness control, which is possible to achieve using the ESA technique, the optimal layer thickness has been adjusted to the maximum slope point of the transmitted optical power curve as a function of the overlay thickness. An optimal working point sensor is compared to a nonoptimal one demonstrating the sensitivity difference between both.     

Resistive humidity sensor based on vanadium complex films

A resistive-type relative humidity （RH） sensor based on vanadium complex （VO2（3-f[）） film is reported in this study. Gold electrodes were deposited on the glass substrates in a co-planar structure. A thin film of vanadium complex was coated as a humidity-sensing material on the top of the pre-patterned electrodes. The humidity-sensing principle of the sensor was based on the conductivity change of coated sensing element upon adsorption/desorption of water vapor. The resistance of the humidity sensor measured at 1 kHz decreased linearly with increasing the humidity in the range of 35%-70% RH. The overall resistance of the sensor decreases 11 times. An equivalent circuit for the VO2（3-fl） based resistive-type humidity sensor was developed. The properties of the sensor studied in this work make it beneficial for use in the instruments for environmental monitoring of humidity.     

基于MSM结构的表面等离子体共振光纤折射率传感器

基于表面等离子体共振(SPR)效应,设计了一种基于多模-单模-多模(MSM)结构的光纤折射率传感器。采用光纤熔接的方式构成MSM结构,并且在单模光纤的表面涂覆二氧化钛/银(TiO2/Ag)复合膜构成传感单元。利用FDTD Solutions仿真分析了单模光纤长度与金属膜厚度对传感器性能的影响。结果表明:单模光纤长度越长,共振深度越深;TiO2/Ag复合膜中Ag膜厚度为50nm,TiO2膜厚度为20nm时,传感器性能最优,在1.33~1.41环境折射率范围内,传感器的灵敏度约为6 875nm/RIU。实验结果表明该光纤折射率传感器结构制作工艺简单、灵敏度高。     

PCF-multimode/endless fiber sensor for respiratory rate monitoring

A respiratory monitoring system was proposed based on optical fiber. The sensor consists of photonic crystal fiber (PCF) spliced with multimode fiber (MMF) to fabricate Michelson interferometer. The sensor is inserted into an oxygen mask tube and then put on the nose and mouth to monitor the respiratory rate (RR) for different cases. The results showed that when breathing increased, the intensity of light decreased. The intensity of light in the sleeping case of breathing was more intense than that when the intensity of working sport was measured. The working sport case was a higher transmittance than that of sleeping. The sensitivity of the sensor was also measured to be 231.9 pm/RH.     

填充型增敏式光子晶体光纤压力传感器结构

为了实现光纤传感器压力增敏的效果,设计了一种具有高双折射的光子晶体光纤结构。采用有限元法计算光子晶体光纤在不同应力作用下的有效折射率, 基于光子晶体光纤的压敏特性,分析光子晶体光纤的模式, 并选择该结构里的一个空气孔,填充具有特定折射率的液体材料,构成新型压力传感器。该结构的压力灵敏度由COMSOL软件的仿真得出。结果表明, 经填充液体后,偏振相位灵敏度从72rad/(MPa·m)提升至128rad/(MPa·m),显著提高了77.7%。该研究对增强传感器的力学性能有帮助。