Multiplex Single Molecule Detection Module for Stroke Diagnosis

A polymer-based, multiplex single molecule detection module (SMD) was developed with a fluidic substrate and a cover plate. The fluidic substrate was fabricated using a single-step, double-sided hot embossing in poly(methyl methacrylate) (PMMA) with sampling zone microchannels on the bottom side and microlenses on the top. Shallow sampling zone microchannels (5 μm deep and 100 μm wide) were made to improve sampling efficiency and microlenses were adopted to collect the fluorescent radiation from the sampling zone microchannels. A cyclic olefin copolymer (COC) embedded waveguide in PMMA along with an integrated coupling prism was fabricated using polydimethylsiloxane (PDMS) stencils and melted COC (40% w/v in toluene) on the cover plate. The COC waveguide with a COC integrated coupling prism will be used for evanescent excitation of fluorescent samples in the sampling zone microchannels. The fluidic substrate was bonded with the cover plate using thermal fusion bonding based on a pressure-assisted boiling point control system. This approach allowed for sealing of shallow microchannels without observable sagging of the cover plate, which was confirmed by leakage testing with fluorescent dyes. The completed SMD module will be tested for characterization of the optical performances such as signal-to-noise ratio and sampling efficiency and it will provide the capability for rapid screening of stroke at low cost.