Enhanced optical trapping by concentrated local fields in metallic semi-continuous films.

ABSTRACT: On-chip optical trapping necessitates substrates that generate strong near-field forces while mitigating thermal instability. Here, metallic semi-continuous films are established as a transformative platform for high-efficiency optical manipulation. Through controlled sputter deposition, we engineer gold films across three morphological regimes: discontinuous nanoparticles (NPs), semi-continuous films (SCFs), and continuous films (CFs). Optical trapping experiments with 500-nm polystyrene spheres reveal that SCF substrates achieve a peak stiffness of 0.0955 ± 8.0 × 10^- 4 pN/µm, representing 16.9× and 6.2× enhancements over NP and CF substrates, respectively. The performance arises from sub-12-nm nanogaps within percolated gold networks, which concentrates electromagnetic fields

SUBMITTER: Liu C 

PROVIDER: S-EPMC12605849 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature