Femtosecond Laser Written Waveguides for Fluorescence-sensing during Microchip Capillary Electrophoresis

The substitution of conventional bench-top instrumentation by fully integrated lab-on-chip systems continues to be a challenge. The integration of microfluidics and integrated optics in glass is an important step towards this goal, forming the focus of this work [1]. In particular, excitation and detection of fluorescence emitted by labeled biomolecules flowing through a microfluidic channel is considered. Excitation occurs at specific wavelengths by means of waveguides inscribed with femtosecond laser pulses in a commercial, glass lab-on-chip. A widely known diagnostic application that will exploit this sensing scheme is the monitoring of microchip capillary electrophoresis (MCE) leading to separation of DNA fragments of different lengths, labeled with fluorescent dye molecules. In order to meet the resolution demands of MCE separation and to achieve multi-point sensing, we envision a device consisting of on-chip integrated optical splitters written coplanar with the microfluidic channel along which MCE separation takes place (Figure 1).