Plasmonic nano-optical trap stiffness measurements and design optimization

Abstract

Plasmonic nano-optical tweezers enable the non-invasive manipulation of nano-objects under low illumination intensities, and have become a powerful tool for nanotechnology and biophysics. However, measuring the trap stiffness of nanotweezers...

Single Photon Source from a Nanoantenna-Trapped Single Quantum Dot

“…We have selected this antenna design so as to yield strong intensity gradient at 1064 nm while keeping a high intensity enhancement at 635 nm (Figure 1b). As compared to the double nanohole design, 53,54 the intensity enhancement for the 635 nm laser in the center of the gap is about 3 times higher which directly improves the photoemission of the trapped quantum dot (Figure S3). While doing preliminary trapping experiments on nanoantennas using two gold hemispheres like the ones used in refs 10 and 55, we observed trapping events of multiple nanoparticles, which were attributed to the intensity hot spots occurring on the opposite extreme edges of the dimer antenna.…”

“…To quantify the trap performance of our nanoantennas with QDs, we use the correlation approach described in our earlier works. , Briefly, the temporal correlation of the PL intensity recorded during a trapping event is computed (Figure d). This correlation decays as where the characteristic correlation time corresponds to the ratio of the Stokes drag coefficient by the trap stiffness .…”

Visualization of Optical Vortex Forces Acting on Au Nanoparticles Transported in Nanofluidic Channels

“…Regarding nanoscale research, although theoretical studies are largely spread, infinitesimal optical forces acting on nanoscale ( d p < 100 nm) particles often fail to overcome thermal fluctuations, preventing researchers from experimentally analyzing optical forces at the nanoscale. Particularly, there are few reports regarding the scattering force acting on nanoscale particles, whereas the gradient force (i.e., trapping stiffness) has been reported in recent studies. , Zensen et al succeeded in evaluating the scattering force acting on Au NPs with a diameter of 80 nm using two Gaussian beams with a specialized microscopic system. They reported a scattering force on the order of 10 fN with an accuracy on the order of 1 fN, which, to the best of our knowledge, is currently the best achieved accuracy.…”

“…Particularly, there are few reports regarding the scattering force acting on nanoscale particles, whereas the gradient force (i.e., trapping stiffness) has been reported in recent studies. 35,36 Zensen et al 27 succeeded in evaluating the scattering force acting on Au NPs with a diameter of 80 nm using two Gaussian beams with a specialized microscopic system. They reported a scattering force on the order of 10 fN with an accuracy on the order of 1 fN, which, to the best of our knowledge, is currently the best The ratio between experimental and numerical results is defined as follows: the ratio of the orbital radius r t was obtained from the leastsquares fitting shown in Figure 4a,d, and g.…”

A 3D Biocompatible Plasmonic Tweezer for Single Cell Manipulation

“…Recently, plasmonic tweezers [ 12 ] have been developed as a non‐contact and damage‐free trapping technique. Trapping of nanoparticles including cells by plasmonic nanostructures, such as gold nanoisland, [ 13 ] nanoholes, [ 14 ] disks, [ 15 ] metal nanocavity, [ 16 ] bowtie plasmonic aperture, [ 17 ] double nanohole apertures, [ 18 ] and surface plasmon lens [ 19 ] has been reported. Rather, the fabrication of these plasmonic structures usually requires the use of high‐resolution means such as electron‐beam lithography and focused‐ion beam, or complex chemical synthesis procedures, imposing high‐cost limitations on their applications.…”