Miniaturized thermal lens and fluorescence detection system for microchemical chips

We have developed a miniaturized two-way detection system using thermal lens and fluorescence spectroscopies for microchip chemistry. The system was composed of laser diode (LD) modules, fiber-based optics combined with a gradient index lens, and miniaturized detection units for thermal lens and fluorescence signals. The detection limits in the thermal lens and fluorescence spectroscopies were 6.3 × 10−9 M for Ni(II) phthalocyanine tetrasulfonic acid and 3.0 × 10−9 M for cy5, respectively. The performance of the system with the miniaturized thermal lens was equivalent to that of a conventional thermal lens microscope. The fluorescence sensitivity was comparable to sensitivities offered by conventional miniaturized systems.