Large-scale, high-uniformity evanescent field illumination via a cost-effective polymer-integrated optical waveguide

Evanescent field illumination (EFI) offers a promising solution to overcome the fundamental limitations in illumination uniformity, signal-to-noise ratio (SNR), and detection throughput for quantitative fluorescence analysis. The development of EFI chips faces tradeoffs between system complexity, illumination area, and manufacturing scalability. In this paper, a compact optical waveguide chip capable of generating excellent detection throughput (large-scale), highly uniform EFI via total internal reflection (TIR) on a waveguide surface is presented that consists solely of an integrated aspheric coupling lens and a standard microscope slide-sized planar waveguide (75 mm × 25 mm). High-precision (Ra < 5 nm), mass-producible fabrication of this chip using polystyrene (PS) through injection molding processes is demonstrated. Experimental results reveal a substantial 2.01 mm alignment tolerance in light coupling while producing highly uniform EFI over large areas (>12 mm × 12 mm, CV < 6%), requiring no complex auxiliary systems.