Integrated miniaturized optical detection platform for fluorescence and absorption spectroscopy

This paper presents the design and fabrication of a miniaturized optical detection system for sensing in microchannels, based on integrated optical waveguide technology. This design allows the implementation of both absorption and fluorescence measurement schemes and can be potentially integrated into a lab-on-a-chip system. An array of optical waveguides were fabricated in spin-on polymer technology on a silicon substrate and monolithically integrated with the microfluidic channel and V-groove fibre alignment scheme. The design was adapted to achieve minimum optical losses under the imposed fabrication constraints. Total system losses with a water filled microchannel were experimentally determined to be 10.45 dB. Both fluorescence and absorption detection capabilities of the fabricated device were demonstrated using Alexa Fluor 633 dye, and the corresponding detection limits were found to be 10 nM and 1 μM, respectively. Several areas of improvements in the device design and fabrication have been identified for future works towards better integration for lab-on-a-chip system.