KCS

The combination of surface-enhanced Raman scattering (SERS) with microfluidic devices provides an ideal mechanism for achieving rapid, sensitive and reproducible detection of specific biomarkers in solution. An additional benefit of such platform is the use of minimal sample volumes and low analyte concentrations. We recently reported a SERS-based wash-free magnetic immunoassay technique using magnet-embedded droplet microfluidics. In this platform, the assay could be performed without any washing process by separating immunocomplexes from the supernatant solution using a magnetic separation. Nonetheless, this methodology still limited in assay because the channel structure for reagents injection and mixing is unified in a channel. To resolve this problem, a new class of microdroplet-merging device was designed and fabricated for sequential immunoassay. This device is composed of five distinct compartments such as droplets merging, separating immunocomplexes from supernatant solution, isolating magnetic immunocomplex droplets, and collecting unbound SERS probe droplets for detection. Herein, we report a novel SERS-based wash-free immunoassay device composed of compartments for mixing, merging, splitting and detection.