Microlens systems for fluorescence detection in chemical microsystems

Micro-optical systems based on refractive microlenses are in- vestigated. These systems are integrated on a chemical chip. They focus an excitation beam into the detection volume (microliter or even submi- croliter scale) and collect the emitted light from fluorescent molecules. The fluorescence must be carefully separated by spatial and spectral filtering from the excitation. This paper presents the ray tracing simula- tion, fabrication, and measurement of three illumination systems. The measurements show that an adroit placement and combination of micro- fabricated lenses and stops can increase the separation between the excitation light and the fluorescence light. Moreover we present the suc- cessful detection of a 20 nM Cy5™ (Amersham Life Science Ltd.) solu- tion in a 100-mm-wide and 50-mm-deep microchannel (excitation volume '250 pL) using one of these illumination systems. The microchemical chip with the micro-optical system has a thickness of less than 2 mm. © 2001 Society of Photo-Optical Instrumentation Engineers. (DOI: 10.1117/1.1359522)

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