Ultra-small four-emission-point spectral-detection system using seven-dichroic-mirror array.

An ultra-small and highly efficient spectral-detection system for four emission points was developed by integrating an injection-molded-plastic four-lens array, a seven-dichroic-mirror array, and an image sensor as one device. The seven-dichroic-mirror array was further miniaturized compared to our previous four-dichroic-mirror array by measures including reduction of the thickness of each dichroic mirror from 1.0 to 0.5 mm. As a result, the system enables highly sensitive and low-crosstalk seven-color detection of laser-induced fluorescence from four emission points of a four-capillary array. This capability allows simultaneous quantification of up-to-seven fluorophores concurrently present in each capillary. Sanger DNA sequencing and STR genotyping by four-capillary-array electrophoresis were experimentally demonstrated by the system.