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

为了高灵敏度、宽频带地测量生化物质和离子溶液的浓度，在优化波导结构的理论考虑基础上，研制了薄膜光波导传感器。采用衬底（包覆）层、波导（芯）层和样品（包覆）层三层板状光波导结构。本文从理论和实验两方面对测量器件灵敏度的倏逝场吸收灵敏度、波导复传播常数和波导传感器与水吸收光物质的相互作用比进行了研究。耐热玻璃平板（折射率n= 1）。衬底层分别采用n=1.58的rf溅射康宁7059玻璃，波导层采用n=1.58的rf溅射玻璃。包覆层由空气层和样品层组成，样品层上滴入极少量生化水溶液。光学传感的原理是基于叶片在特定波长下更多的气味场吸收生化分子和离子。用消失场吸收法测定氧、脱氧血红蛋白浓度和葡萄糖浓度。采用旋涂法制备了另一种具有复合聚合物（PVCPVA）芯层（n= 1.51）的波导。在复合聚合物中，离子选择性离子载体和特定染料被掺杂，其传感机制依赖于目标离子与离子载体特异性结合时被掺杂介质的光吸收变化。通过改变离子载体，可以选择性地检测Na、K或Ca离子的浓度。这种类型的传感器不是通过倏逝场吸收而是通过体吸收来工作的。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差。这是由于有效试样的厚度和长度与穿透深度和倏逝波的长度成正比。所提出的光波导传感器具有足够高的倏逝场与样品介质的相互作用长度，可实现高灵敏度和大范围的浓度测量。本研究还提出了一种利用指数响应曲线拟合计算离子浓度的短时测量新方法。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