FIBER OPTIC SENSORS BASED ON POLMER SWELLING

基于聚合物膨胀的光纤传感器

• 批准号: 2727336
• 负责人: Rudolf W. Seitz
• 金额: $ 10.16万
• 依托单位: UNIVERSITY OF NEW HAMPSHIRE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2002-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2727336
• 关键词: biosensor device; fiber optics; hydropathy; membrane permeability; microcapsule; polymerization; polymers; technology /technique development; telemetry

We are developing optically sensitive membranes that consist of lightly crosslinked, derivatized polystyrene microspheres embedded in a hydrogel. The microspheres are designed to swell and shrink as a function of analyte concentration. The optical properties of the membrane are affected by both the change in size of the microsphere and the change in refractive index that accompanies swelling. This can be measured either as a change in membrane turbidity or reflectance. This effect avoids the use of photosensitive indicators and makes it possible to remotely measure optical changes in the near infrared using technology developed for fiber optic communications. We have already developed membranes that respond reversibly and sensitively to pH. In addition, we have demonstrated the feasibility of ion selective detection using poly(4-hydroxy,3- nitrostyrene) microspheres treated to contain an ionophore. Ion binding by the ionophore is accompanied by deprotonation of the hydroxy group. We also have acquired preliminary data demonstrating the feasibility of remotely measuring changes in pH through several hundred meters of fiber. A pulse of light is introduced into two different lengths of optical fiber using a 2X2 fiber optic coupler. The return pulse is monitored vs. time by a photodiode. The signals from the two fibers are distinguished based on differences in the transit time through the fiber. Research to further develop this remote measurement technology is proposed in five areas: l. Develop procedures for simultaneously and independently controlling microsphere porosity and hydrophilicity using two-step seeded polymerization: The amount of porogenic solvent added in the second polymerization step controls porosity. Hydrophilicity will be controlled by preparing copolymers of styrene and 2,4,5- trichlorophenylacrylate (TCPA) followed by conversion of the TCPA to a more hydrophilic functional group such as an amide. 2. Investigate the effect of reducing the density of derivatized functional groups on the polymer: Based on preliminary observations, we expect to be able to substantially improve our response times by reducing the density of derivatized functional groups on the polymer while retaining excellent sensitivity. 3. Develop ion selective sensors: We will expand upon our demonstration that ion selective detection is feasible by exploring the effects of formulation and ionophore structure on the rate and magnitude of response to cations. We also determine whether the selectivity is as expected based on the ionophore's affinity for different ions. 4. Sensors for two analytes: Turbidity spectra vary with microsphere size. We propose to demonstrate the feasibility of making sensors that simultaneously respond to two analytes by preparing membranes that contain two populations of microspheres that differ in size. For example, we propose to develop a membrane that simultaneously responds to pH and ionic strength by making a membrane that contains large, i.e. ca. 1.5 micrometers in diameter, pH sensitive microspheres and small, i.e. ca. 0.5 to 0.7 micrometers in diameter, ionic strength sensitive microspheres. 5. Remote Measurements through Fiber Optics: We will improve our current system for remote measurements of membrane optical properties by making the measurement at longer wavelengths where Rayleigh scattering is less and by developing new technology for preparing thin membranes on fibers in which the core has been etched to form a small cavity.

我们正在开发的光学敏感膜，包括轻度交联，衍生聚苯乙烯微球嵌入水凝胶。微球被设计为根据分析物浓度膨胀和收缩。膜的光学性质受到微球尺寸变化和伴随溶胀的折射率变化的影响。这可以作为膜浊度或反射率的变化来测量。这一效果避免了使用光敏指示器，并使得有可能使用为光纤通信开发的技术来远程测量近红外的光学变化。我们已经开发出可逆的和敏感的pH值响应膜。此外，我们已经证明了使用聚（4-羟基，3-硝基苯乙烯）微球处理含有离子载体的离子选择性检测的可行性。离子载体的离子结合伴随着羟基的去质子化。我们还获得了初步数据，证明了通过数百米的光纤远程测量pH值变化的可行性。使用2X2光纤耦合器将光脉冲引入两个不同长度的光纤。通过光电二极管监测返回脉冲与时间的关系。基于通过光纤的传输时间的差异来区分来自两个光纤的信号。提出了在五个方面进一步发展这种遥测技术的研究：1。开发使用两步种子聚合同时独立控制微球孔隙率和亲水性的程序：在第二步聚合中添加的致孔溶剂的量控制孔隙率。通过制备苯乙烯和丙烯酸2，4，5-三氯苯酯（TCPA）的共聚物，然后将TCPA转化为更亲水的官能团如酰胺来控制亲水性。2.研究降低聚合物上衍生化官能团密度的影响：根据初步观察，我们期望能够通过降低聚合物上衍生化官能团的密度，同时保持出色的灵敏度，从而大幅提高响应时间。3.开发离子选择性传感器：我们将扩大我们的示范，离子选择性检测是可行的，通过探索配方和离子载体的结构对阳离子的响应速度和幅度的影响。我们还确定选择性是否如预期的基于离子载体对不同离子的亲和力。4.两种分析物的传感器：浊度谱随微球尺寸而变化。我们建议证明的可行性，使传感器，同时响应两种分析物，通过制备膜，包含两个群体的微球的大小不同。例如，我们提出开发一种膜，该膜通过制备含有大的，即约1000 μ g/ml的，1.5微米直径，pH敏感的微球和小，即约。0.5至0.7微米直径的离子强度敏感微球。5.通过光纤的远程测量：我们将通过在瑞利散射较少的较长波长下进行测量，并通过开发在光纤上制备薄膜的新技术来改进我们目前的膜光学特性远程测量系统，其中核心已被蚀刻以形成小腔。