Low-Power Optical Trapping of Nanoparticles and Proteins with Resonant Coaxial Nanoaperture Using 10 nm Gap

Abstract

We present optical trapping with a 10 nm gap resonant coaxial nanoaperture in a gold film. Large arrays of 600 resonant plasmonic coaxial nanoaperture traps are produced on a single chip via atomic layer lithography with each aperture tuned to match a 785 nm laser source. We show that these single coaxial apertures can act as efficient nanotweezers with a sharp potential well, capable of trapping 30 nm polystyrene nanoparticles and streptavidin molecules with a laser power as low as 4.7 mW. Furthermore, the resonant coaxial nanoaperture enables real-time label-free detection of the trapping events via simple transmission measurements. Our fabrication technique is scalable and reproducible, since the critical nanogap dimension is defined by atomic layer deposition. Thus our platform shows significant potential to push the limit of optical trapping technologies.

Temperature Measurement in Plasmonic Nanoapertures Used for Optical Trapping

“…58 Fluorescence correlation spectroscopy (FCS) is a well-established technique to probe the molecular translational diffusion and record the mean diffusion time of the fluorescent dyes across the detection volume. [47][48][49][50] Since the FCS diffusion time is proportional to 1/ ( ), the change in the FCS diffusion time can then be computed back into a temperature change using the Stokes-Einstein equation (7). 43,45,[51][52][53] Here we neglect the influence of the convection phenomenon as it has been reported that convection flows played a negligible role inside the nanoaperture.…”

“…1 These intense field gradients enable efficient nano-optical trapping of nanoparticles and even single molecules. [2][3][4][5][6][7] Such unprecedented ability to locate a nanoparticle and/or a quantum emitter with nanometer accuracy opens promising opportunities for many applications in biosciences and quantum information processing. [8][9][10][11][12][13][14] Among the different plasmonic nanostructures used for nano-optical trapping, single and double nanoholes milled in gold films have been widely used.…”

Plasmonic optical tweezers based on nanostructures: fundamentals, advances and prospects

“…This coaxial nanoaperture design provides for selective trapping of small particles based on their chiralities and a method to study their interactions with other chiral components [146]. More recently, Yoo et al demonstrated optical trapping of a 30 nm polystyrene particle and streptavidin molecules with a laser power at 4.5 mW by employing a 10-nm gap resonant coaxial nanoaperture in a gold film ( Figure 3F) [128]. Specifically, the authors selected the first-order Fabry-Pérot mode of the coaxial nanoaperture due to the ease in tuning the resonance in the near infrared to stably trap protein molecules within 3 min in a reproducible manner [128].…”

Sub‐5 nm Metal Nanogaps: Physical Properties, Fabrication Methods, and Device Applications

“…For both molecular devices and sensing devices, the trapping efficiency is an important factor in their practical application. Taking advantage of the sub‐5 nm nanogap, low energy consumption trapping devices with high efficiency were achieved using an ultralow bias voltage or laser power …”