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

为了实现对生化物质和离子溶液浓度的高灵敏度、宽频带测量，在对最佳波导结构进行理论分析的基础上，研制了薄膜光波导传感器。三层平板型光波导由基片（包层）、波导（芯层）和样品（包层）构成。理论和实验研究了作为器件灵敏度度量的倏逝场吸收灵敏度、波导的复传播常数和波导传感器与水溶液光吸收组分的相互作用比。分别使用Pyrex玻璃板（折射率n= 1.47）作为衬底层和RF溅射Corning 7059玻璃（n=1.58）作为波导层。上覆层由空气层和试样层组成，试样层上滴有极少量的生化水溶液。光学传感的原理是基于evane ...更多信息 在特定光波长下生物化学分子和离子的气味场吸收。氧和脱氧血红蛋白浓度和葡萄糖浓度与化学反应酶的测定，通过使用倏逝场吸收法。另一种类型的具有复合聚合物（PVCPVA）芯层（n= 1.51）的波导也通过旋涂方法开发。在复合聚合物中掺杂离子选择性离子载体和特异性染料，其传感机理依赖于目标离子与离子载体特异性结合时掺杂介质光吸收的变化。Na、K或Ca离子的浓度通过改变各自的离子载体来选择性地检测。这种类型的传感器的功能不是由倏逝场吸收，而是由体积吸收。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低。这是由于有效样品厚度和长度与倏逝波的穿透深度和长度的数量级相同。该光波导传感器具有足够大的倏逝场与样品介质的相互作用长度，可用于高灵敏度和宽范围的浓度测量。本文还提出了一种利用指数响应曲线拟合的短时测量离子浓度计算方法。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