High Sensitive Detection of Biochemical Substances Using by Thin-film Optical Waveguide Sensor

为了实现高灵敏度、宽频带的生化物质和离子溶液浓度的测量，在理论考虑优化光波导结构的基础上，研制了薄膜光波导传感器。由基片(包层)层、波导层(芯)层和样品(包层)层构成三层板状光波导。从理论和实验上研究了作为器件灵敏度指标的消失场吸收灵敏度、光波导复传输常数和光传感器与水溶液的相互作用比。基板采用PYREX玻璃(折射率n=1.47)，波导层采用射频溅射康宁7059玻璃(n=1.58)。顶层由空气层和样品层组成，样品层上滴有极少量的生化水溶液。基于EVANE…的光学传感原理在特定的光波长处，生物化学分子和离子的香气场吸收更多。用消失场吸收法测化学反应酶法测氧、脱氧血红蛋白浓度和葡萄糖浓度。另一种具有复合聚合物(PVCPVA)芯层(n=1.51)的光波导也是用旋涂的方法制成的。在复合聚合物中，掺杂了离子选择性离子载体和特定染料，其传感机理依赖于当目标离子与离子载体特定结合时掺杂介质的光吸收的变化。通过改变各自的离子载体来选择性地检测Na、K或Ca离子的浓度。这种类型的传感器的功能不是通过消失场吸收，而是通过体吸收。传统ATR分光光度法的局限性之一是对弱光吸收样品的灵敏度较低。这是因为有效样品的厚度和长度按穿透深度和消逝波长度的顺序排列。提出的光波导传感头具有足够长的衰减场与样品间的相互作用长度，可用于高灵敏度、宽范围的浓度测量。在本研究中，还提出了一种新的用于离子浓度计算的短时测量方法，即指数响应曲线拟合法。较少

In order to measure concentration of biochemical substances and ion solutions with high sensitivity and wide range band, thin-film optical waveguide sensor was developed under the basis of theoretical consideration of optimal waveguide construction. Three layers slab type of optical waveguide was constructed by substrate (clad) layer, waveguide (core) layer and sample (clad) layer. Sensitivity of evanescent field absorption, complex propagation constant of the waveguiding and interaction ratio of the waveguide sensor to aqueous light-absorbing species, which are measure of device sensitivity, were theoretically and experimentally investigated. Pyrex glass plate (refractive index n=l.47) for the substrate layer and rf-sputtered Corning 7059 glass (n=1.58) for the waveguide layer were used respectively. Top clad layer was composecd by air layer and sample layer on which very small quantity of biochemical aqueous solution was droped. Principle of the optical sensing was based on the evane … More scent field absorption of biochemical molecules and ions at the specific light wavelength. Oxy- and deoxyhemoglobin concentration and glucose concentration with chemo-reactive enzyme were measured by using the evanescent field absorption method. Another type of waveguide having composite polymer (PVCPVA) core layer (n=l.51) was also developed by means of spin-coating method. In the composite polymer, ion selective ionophore and specific dye were doped, of which sensing mechanism was dependent on changing of light absorption of the doped medium when the objective ion was specifically combined with the ionophore. Concentration of Na, K or Ca ion was selectively detected by changing the respective ionophores. This type of sensor was functioned not by evanescent field absorption but by bulk absorption. One of limitations of conventional ATR spectrophotometry was poor sensitivity for weakly light absorbing samples. This arises from that the effective sample thickness and length are in the order of penetration depth and length of the evanescent wave. The proposed optical waveguide sensor gave enough high interaction length between the evanescent field and sample meidum and therefore it was available to high sensitivity and wide range of concentration measurement. In this study, a new method of short time measurement for ion concentration calculation was also proposed by using exponential response curve fitting. Less