Highly precise thermal imprinting of microstructures for optical sensing application

This study investigates the improvement of planar waveguide performance for advanced optical sensors by optimized hot embossing on polymethylmethacrylate (PMMA) substrates with Ormocomp photoresist and integration of zeolite imidazole framework-8 (ZIF-8). We have produced planar waveguides with significantly reduced optical transmission losses of 2.32 dB/cm which is suited for the sensing application intended. The integration of ZIF-8-based optical films improves carbon dioxide (CO₂) sensing, with adsorption taking 55 seconds and desorption only 10 seconds, achieving a sensitivity of about 7 μW/5 vol% and demonstrating excellent reversibility of gas adsorption/desorption cycles. Future research will investigate different photoresists to further optimize waveguide performance and expand application cases. This study may thus lay the foundation for next optical sensing technologies in the biomedical, environmental, and industrial fields based of functionalized planar-optical waveguide arrays.