提高荧光收集效率的新型微流控芯片检测系统

分析了微流控芯片荧光检测系统,推导了其荧光收集效率,考虑了通道内介质和透镜与微芯片间介质的影响.根据分析结果提出了一种基于普通显微物镜的新型激光诱导荧光检测系统设计,在微芯上胶合棱镜,实现激发光的大角度斜照明.胶合镀有反射膜的椭球透镜作为反光碗,进行背向荧光的反射收集,加入折射率匹配液,减小荧光的发散角度.系统降低了收集物镜工作距离的要求,荧光收集效率比利用常规结构的显微物镜荧光检测系统理论上最高可提高6.3倍,模拟实验结果为4.3倍.

New system arrangement for the improvement of fluorescence collecting efficiency in microfluidic chip detection

Microfluidic chip detection system based on laser-induced fluorescence was analyzed. Fluorescence collecting effidency of the system was developed,in which refractive index of medium in microchannel and that between the microchip and objective lens were considered. A new optical arrangement of laser-induced fluorescence with high fluorescence collecting efficiency was presented,which adopted an ordinary microscope objective without long working distant and high numeric aperture. Converging exciting laser bevel illumination with high deflecting angle was achieved by a prism cemented on the microchip. Elliptical sphere lens coated with reflecting film was used as a reflector to attain collecting of backward fluorescence. Refractive index matching liquid was added to reduce the fluorescence divergence angle from the microchip surface. The system reduced the requirement for working distance of the collecting objective lens greatly. Compared with traditional fluorescence detecting structure, fluorescence collecting efficiency could be improved up to about 6.3 times. The experimental result by ray-tracing is about 4.3 because of the influence of structure of objective lens and the cross section profile of microchannel.