Fabrication of Bowl Array Surface-Enhanced Raman Scattering Substrates via Ag Nanoparticle Self-Assembly on Polymer UV-Imprinted Microbowls for Enhanced Raman Detection of Microplastics

A facile, efficient, and cost-effective strategy for fabricating a bowl array SERS (surface-enhanced Raman scattering) substrate is presented. The resulting substrate is dimensionally compatible with micrometer-sized microplastics and integrates both SERS enhancement and light-trapping effects, enabling highly sensitive detection of micrometer-sized microplastics. Initially, a pillar array template was produced via UV lithography, followed by UV imprinting to replicate bowl arrays with a diameter of 50 μm, a depth of 25 μm, and a periodicity of 100 μm. A gold layer was subsequently deposited, followed by the modification of its surface with AgNPs to construct the SERS substrate. The experimental results reveal that the optimal enhancement was achieved at an AgNP suspension concentration of 15 mg/mL. The substrate exhibited a detection limit of 10-9 M for rhodamine 6G with an enhancement factor (EF) of 2.02 × 107 and successfully detected polyethylene (PE) microplastics of 5, 10, and 20 μm at concentrations down to 100 μg/mL, demonstrating outstanding sensing performance.