Plasmonic Nanometric Optical Tweezers in an Asymmetric Space of Gold Nanostructured Substrates – Pages 2-10

Kodai Hirano1, Hisashi Shimizu1, Taira Enami1, Mitsuhiro Terakawa1, Minoru Obara1, Nikolay N. Nedyalkov2 and Petar A. Atanasov2

1School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama-shi, 223-8522, Japan; 2Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko Shousse 72, Sofia 1784, Bulgaria



Abstract: We present a plasmonic near-field tweezers in water with gold nanosphere pairs on various substrates. An enhanced near field localized in the nanometric gap space pumped with 800 nm femtosecond laser is to trap and kill small viruses. The maximal optical trapping force obtained is larger than 20 pN at an incident optical peak intensity of 1 mW/mm2. We also propose a new system consisting of a gold nanosphere and a gold nanoridge. In this system, the enhanced near field stems mainly from the image charge effect, exhibiting an optical trapping in an asymmetric space. The calculated trapping force is equivalent to the system of gold nanosphere pairs. The trapped viruses may easily be inactivated using a unfocused 800 nm femtosecond laser.

Keywords: Plasmonic optical tweezers, near field optics, optical trapping, plasmonic dialysis of viruses ex vivo, femtosecond laser.