The authors report a combination of the enhanced transmission effect and shape resonances in a periodic array of nanoscale double-hole structures in a gold film to enhance the detection sensitivity of surface plasmon biosensors. Finite-difference time-domain calculations are used to quantify field enhancement at the apexes of the double-hole structure. The double-hole array was used to measure the formation of a self-assembled monolayer and for real-time sensing of protein adsorption onto a gold surface. This result demonstrates the potential to integrate propagating surface plasmons and localized shape resonances to improve real-time biosensors.
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The authors acknowledge Adam McFarland, Christy Haynes, Jennifer Maynard, and Anand Gopinath for helpful discussions. Device fabrication was performed at the Minnesota NanoFabrication Center, which receives support from the National Science Foundation through the National Nanotechnology Infrastructure Network (NNIN).