Integrating optical waveguides in electrowetting-on-dielectric digital microfluidic chips

Readout through a microscope-based setup is one of the most prevalent optical detection methods used in current digital (i.e. droplet-based) electrowetting-on-dielectric lab-on-chip devices. The integration of waveguides on such devices allows further size and complexity reduction for absorption, fluorescence and surface plasmon resonance based detection mechanisms. In this paper, we show a straightforward method to integrate multimode polymer optical waveguides on an EWOD device. A proof-of-concept system is presented that allows droplets to be transported by EWOD actuation to a gap between two opposing waveguides down to 300 μm in size, and engulf the integrated waveguides for transmission measurements. The system is validated using a gold nanoparticle based model assay.