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光纤倏逝波生物传感器光纤探头的耦合光束限定 总被引:3,自引:0,他引:3
根据光纤的模式匹配理论计算了给定条件下光纤探头的模式匹配半径,以此匹配半径为基础分析了激发光在锥型光纤探头中的光线传输轨迹.结果表明,在此条件下如不对光纤探头的耦合光束进行限定,将有一部分激发光在锥型光纤探头中因不满足全反射的传输条件而透射出光纤探头,从而使传感器系统得到虚假检测信息.针对此问题,在光纤倏逝波生物传感器的系统设计中给出了具体的解决方法. 相似文献
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《光学学报》2018,(10)
为了满足对环境中重金属污染物汞离子的快速、现场及高灵敏度检测需求,利用汞离子对量子点产生荧光猝灭效应,结合光纤倏逝波传感原理,自主研发了一套可用于汞离子检测的全光纤传感器。其主要由光纤探针、光学系统和信号处理系统构成,实现了荧光信号的激发、探测以及光电信息的处理和获取。实验表明该传感器对汞离子的检出限可达到1nmol/L,且在1nmol/L至500nmol/L的浓度范围内,量子点的荧光猝灭率随汞离子的浓度对数呈线性变化规律,线性相关度为0.9867。同时,离子抗干扰实验证实了该传感器对汞离子具有良好的选择性识别检测能力,将其应用于实际水样检测的加标回收率为90.1%~97.3%。该传感系统灵敏度高、响应速度快,可以实现远程探测和实时监测,且有利于仪器的集成和小型化,在重金属离子污染检测等领域具有广阔的应用前景。 相似文献
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将新型量子点荧光传感技术与光纤倏逝波传感技术相结合,发展了一种基于量子点荧光效应并结合倏逝波传导进行溶液酸碱度检测的新型传感技术,具有灵敏度高、检测速度快、便于微环境检测、可实现远程探测、实时监测和原位分析等特点。详细介绍了用于倏逝波传感的锥柱组合型光纤荧光探头的制备方法,量子点在光纤探头表面的修饰流程,光谱与强度两种光纤pH传感平台的建立,并分别从响应范围、线性度、重复性和稳定性等方面对CdSe/ZnS量子点应用于光纤pH传感进行了评价。结果表明,在pH值为2~12的范围内,CdSe/ZnS量子点的荧光光谱信号的峰位在强酸和强碱的情况下都会产生红移,且红移量随pH值的变化呈线性关系,其量子点荧光强度信号随pH值的减小呈线性降低关系,通过在强酸和强碱下交替测试的实验表明其具有较好的重复性,利用荧光强度传感平台进行实时监测的实验表明其具有较好的稳定性。因此,将CdSe/ZnS量子点用于倏逝波光纤pH传感具有可行性,在生物化学、环境监测、医学临床、食品安全等领域的pH值测量方面有着广泛的应用前景。 相似文献
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本文结合近场扫描结构和纳米线-微光纤耦合技术,提出了一种基于硫化镉纳米线/锥形微光纤探针结构的被动近场光学扫描成像系统.该系统采用被动式纳米探针,保留了纳米探针对样品表面反射光的强约束优势.其理论收集效率为4.65‰,相比于传统的金属镀膜近场探针收集效率提高了一个数量级,可有效地提高扫描探针对样品形貌信息的检测能力;而后通过硫化镉纳米线与微光纤之间高效的倏逝场耦合,将检测的光强信号传输到远场进行光电探测,最终实现对目标样品形貌的分析成像,其样品宽度测量误差在7.28%以内.该系统不需要外部激发光路,利用显微镜自身光源进行远场照明,被动扫描探针仅作为样品表面反射光的被动收集系统.本文基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像方案,可有效地降低探针的制备难度和目标光场的检测难度,简化扫描成像的结构,为近场光学扫描显微系统之后的发展提供新的思路. 相似文献
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本文结合近场扫描结构和纳米线-微光纤耦合技术,提出了一种基于硫化镉纳米线/锥形微光纤探针结构的被动近场光学扫描成像系统.该系统采用被动式纳米探针,保留了纳米探针对样品表面反射光的强约束优势.其理论收集效率为4.65‰,相比于传统的金属镀膜近场探针收集效率提高了一个数量级,可有效地提高扫描探针对样品形貌信息的检测能力;而后通过硫化镉纳米线与微光纤之间高效的倏逝场耦合,将检测的光强信号传输到远场进行光电探测,最终实现对目标样品形貌的分析成像,其样品宽度测量误差在7.28%以内.该系统不需要外部激发光路,利用显微镜自身光源进行远场照明,被动扫描探针仅作为样品表面反射光的被动收集系统.本文基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像方案,可有效地降低探针的制备难度和目标光场的检测难度,简化扫描成像的结构,为近场光学扫描显微系统之后的发展提供新的思路. 相似文献
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Haridas J. Kharat Kishor P. Kakde Dhammanand J. Shirale Vikas K. Gade Pradeep D. Gaikwad Padmakar A. Savale Mahendra D. Shirsat 《Fiber and Integrated Optics》2006,25(6):411-422
Evanescent wave configuration has been extensively used in the development of fiber-optic sensor for different biomedical applications. In the present investigation we have theoretically proposed the designing of single-mode and multimode optical fiber sensing probes, which can be prepared by removing a few centimeters of cladding near the distal end of the step index optical fiber. In this theoretical study, we found that the removal of cladding causes V-number mismatching and this has led to the loss of signal acquisition from the sensing region. Therefore, to minimize these losses we have proposed to reduce the radius by step etch and tapering technique. It was found that step etching and tapering enhances the strength and penetration depth of the evanescent wave significantly. 相似文献
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Fiber optic evanescent field absorption sensor: Effect of fiber parameters and geometry of the probe 总被引:5,自引:0,他引:5
A comparative experimental study of the fiber-optic evanescent field absorption sensor based on straight and U-shaped probes is presented. The effects of numerical aperture and the core radius of the fiber on the sensitivity of the sensor are experimentally investigated. Increase in the numerical aperture of the fiber increases the sensitivity of the sensor in the case of both the probes. The effect of core radius on the sensitivity depends on the bending radius of the probe. In the case of straight probe (i.e. infinite bending radius) the fiber with smaller core radius has high sensitivity while in the case of U-shaped probe with 0.17 cm bending radius, the fiber with larger core radius has high sensitivity. Thus, which fiber (with small or large core radius) has maximum sensitivity depends on the bending radius of the probe. For a given fiber, decrease in the bending radius increases the sensitivity of the U-shaped probe. An inverse power law relationship between the bending radius and the evanescent absorbance and hence the sensitivity is established. 相似文献
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Haridas J. Kharat Kishor P. Kakde Dhammanand J. Shirale Vikas K. Gade Pradeep D. Gaikwad Padmakar A. Savale 《Fiber and Integrated Optics》2013,32(6):411-422
Evanescent wave configuration has been extensively used in the development of fiber-optic sensor for different biomedical applications. In the present investigation we have theoretically proposed the designing of single-mode and multimode optical fiber sensing probes, which can be prepared by removing a few centimeters of cladding near the distal end of the step index optical fiber. In this theoretical study, we found that the removal of cladding causes V-number mismatching and this has led to the loss of signal acquisition from the sensing region. Therefore, to minimize these losses we have proposed to reduce the radius by step etch and tapering technique. It was found that step etching and tapering enhances the strength and penetration depth of the evanescent wave significantly. 相似文献
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F. B. Xiong W. Z. Zhu H. F. Lin X. G. Meng 《Applied physics. B, Lasers and optics》2014,115(1):129-135
The feasibility of sapphire fiber-optic sensors based on evanescent wave absorption spectroscopy in the infrared range for quantitative determination of water content in polar organic solvents has been investigated. Evanescent wave absorption spectra of sapphire fiber-optic sensors in glycerol, ethanol, and glycol with different water concentrations obtained and analyzed, respectively. Evanescent absorbance of the sensors in those organic solvents has been utilized to implement for in situ monitoring water concentration in organic solvents. The evanescent absorbance of sensors in glycerol and glycol has been found to vary linearly with water content in the range 0–30 % and in ethanol in the range 0–10 %, respectively. The fiber-optic sensors based on evanescent absorbance for monitoring water concentrations in those organic solvents are acceptably accurate, cost-effective, and reliable. Some methods to improve the accuracy of predicated water content in those organic solvents are also suggested. Overall, the results demonstrate that the sapphire fiber-optic sensor based on evanescent absorption spectroscopy is a promising candidate for prediction of water content in polar organic solvents in on-line and remote situation. 相似文献
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A small-volume fiber-optic pH sensor (FOEWS) based on evanescent wave excitation is developed and evaluated. The sensor is
simply fabricated by inserting a decladded optical fiber into a transparent capillary tube. A microchannel between the optical
fiber and the capillary inner wall was formed and acted as flow cell for solution flowing through. The pH-sensitive fluorophore
of fluorescein can be excited by the evanescent wave field produced on the fiber core surface to produce emission fluorescence.
pH value was then sensed by its enhancing effect on the emission fluorescence intensity. The response range of the sensor
is from pH 2.09 to pH 8.85 and the linear range is from pH 3.25 to 8.85. The proposed sensor has a small detection volume
of 2.5 μL and a short response time of 8 s. It has been applied to measure pH values of real water samples and was in good
agreement with the results obtained by commercial pH meter. 相似文献
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Ball lens coupled fiber-optic probe for depth-resolved spectroscopy of epithelial tissue 总被引:6,自引:0,他引:6
Schwarz RA Arifler D Chang SK Pavlova I Hussain IA Mack V Knight B Richards-Kortum R Gillenwater AM 《Optics letters》2005,30(10):1159-1161
A ball lens coupled fiber-optic probe design is described for depth-resolved measurements of the fluorescence and reflectance properties of epithelial tissue. A reflectance target, fluorescence targets, and a two-layer tissue phantom consisting of fluorescent microspheres suspended in collagen are used to characterize the performance of the probe. Localization of the signal to within 300 microm of the probe tip is observed by use of reflectance and fluorescence targets in air. Differential enhancement of the fluorescence signal from the top layer of the two-layer tissue phantom is observed. 相似文献
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An angled fiber-optic probe that facilitates depth-sensitive fluorescence measurements was developed for enhancing detection of epithelial precancers. The probe was tested on solid, two-layered phantoms and proved to be effective in selectively detecting fluorescence from different layers. Specifically, a larger illumination angle provides greater sensitivity to fluorescence from the top layer as well as yielding an overall higher fluorescence signal. Monte Carlo simulations of a theoretical model of the phantoms demonstrate that increasing the illumination angle results in an increased excitation photon density and, thus, in increased fluorescence generated in the top layer. 相似文献