Development of a Sensitive Lazer Spctrophotometric Environmental Monitoring Device Using Droplet Method

研制并应用无源采样装置对大气污染中硫氧化物中的氮氧化物进行了测量。在本工作中，我们将被动采样器方法改为液滴法。然而，由于被动采样器不适合高灵敏度和精确的分析，因此无法监测长期暴露的微量可变有毒物质。为了解决这一缺陷，我们采用了Dasgupta液滴法。我们使用发光二极管和光纤来分析实验中使用的液滴是圆柱形腔。在腔室的中心有一根不锈钢管。它用于交付解决方案。而不锈钢管的尖端总是保持液滴滴下去。气流从两个相对位置的气体入口进入顶部的圆柱形腔室，以实现液滴周围更对称的流动剖面。然后液滴收集气体并改变颜色。高亮度LED发出的光照亮液滴。在完全相反的一侧，透射光通过塑料光纤传导到装有界面滤光器的光电二极管。参考光电二极管被放置在LED的背面，以提供双光束参考检测安排。吸光度计算为-log[(Id-Id‘)/(Ir-lr‘)] +Ko，其中Id和Ir分别是探测器和参考光电二极管产生的光电流，Id’和Ir’是对应的暗电流，Ko是补偿参考光束和指向该滴的探测光束强度之间不平等的偏移常数。我们的目的和目标是将最新的微加工技术应用于液滴法。一个几平方厘米的微芯片可以收集和分析气体样本。此外，微加工的液滴法将提供最小的分析装置，可适用于各种环境样品。

We developed and used the passive sampling device to measure NOx in SOx in air pollution. In the present work we have changed the passive sampler method to the droplet method. Because the passive sampler is, however, not fit to the high sensitivity and precise analysis and, therefore, unable to monitor micro-amounts of variable toxic substances in long period exposure.To meet the solution of disadvantage, we adopted the Dasgupta's droplet method. We use the light-emitting diode and the optical fiber to analyze the droplet which used in the experiment is the cylindrical chamber. In the center of the chamber there is a stainless steel tube. It is used to deliver the solution. And the tip of a stainless tube always keeps the droplet dripping. The gas stream is introduced into the cylindrical chamber at the top, from two oppositely located gas inlets, to achieve more symmetric flow profile around the droplet. Then the droplet collects the gas and is changed the color. The light from a high brightness LED illuminates the droplet. On the diametrically opposite side, the transmitted light is conducted by a plastic optical fiber to a photodiode equipped with an interface filter. A reference photodiode is placed at the back plane of the LED to provide a dual-beam referenced detection arrangement. Absorbance is computed as -log[ (Id-Id')/(Ir-lr') ] +Ko where Id and Ir are the respective photocurrents generated by the detector and the reference photodiode, Id' and Ir' are the corresponding dark currents, and Ko is an offset constant that compensates for the inequality between the intensities of the reference beam and the probe beam directed to the drop.Our purpose and goal are the application of the recent micromachining techniques to the droplet method. A microchip of several centimeter square can collect and analyze the gas sample. Also, microfabrication of the droplet method will give the smallest analysis device which can be applicable to various environmental samples.