Integrated optofluidic micro-pumps in micro-channels with uniform excitation of a polarization rotating beam

Optically levitated conveyor belt based on polarization-dependent metasurface lens arrays

In this Letter, we have proposed an optically levitated conveyor belt based on periodic arrays of a polarization-dependent nanoslit-based metasurface lens (NBML) that is capable of realizing far-field capture, transport, and sorting. The NBML in arrays can be lit up in a relay way by rotating the polarization angle of the excitation beam and thereby provide a better stiffness for transporting particles. When excited at the wavelength of 1064 nm and power density of 0.3 mW/µm², the particles will follow the directional movement of hot spots with an alternative switch of polarization angle and the success ratio of transport can be up to 97.0% with the consideration of Brownian motion. Furthermore, the influence of polarization switching time and incident optical power densities on the efficiency of transport are investigated numerically from a statistical point of view. The sorting of particles with different sizes has also been proved in a given power density. With the analysis of numerical results, our research provides a new approach, to the best of our knowledge, for particle trapping and transport, which is beneficial to on-chip optofluidic applications.

Optical conveyor belt based on a plasmonic metasurface with polarization dependent hot spot arrays

In this Letter, we propose a novel metasurface conveyor belt with periodic orientated arrays of gold plasmonic elliptical elements (GPEEs), which can be continuously lit in a relay way by switching the polarization of the excitation beam and can be used to trap, transport, and sort particles. The array of the hot field can provide a larger trapping area and better stiffness. With the incident optical intensity of 0.08mW/µm², the depth of the potential well could be as high as 10K_BT. By setting a narrow interval between plasmonic ellipses in principal axes, it can help further enhance their directional resonant coupling and polarization dependence. Furthermore, based on consideration of the Brownian motion of trapped particles in aqueous solution, we analyzed its time response property of particle manipulation with different applied switching frequencies from a statistical point of view. As confirmed by numerical analysis, our design offers a novel scheme of particle sorting using a scalable hot spot array with better performance, which could be used in many on-chip optofluidic applications.

Applications of Optically Controlled Gold Nanostructures in Biomedical Engineering

Since their inception, optical tweezers have proven to be a useful tool for improving human understanding of the microscopic world with wide-ranging applications across science. In recent years, they have found many particularly appealing applications in the field of biomedical engineering which harnesses the knowledge and skills in engineering to tackle problems in biology and medicine. Notably, metallic nanostructures like gold nanoparticles have proven to be an excellent tool for OT-based micromanipulation due to their large polarizability and relatively low cytotoxicity. In this article, we review the progress made in the application of optically trapped gold nanomaterials to problems in bioengineering. After an introduction to the basic methods of optical trapping, we give an overview of potential applications to bioengineering specifically: nano/biomaterials, microfluidics, drug delivery, biosensing, biophotonics and imaging, and mechanobiology/single-molecule biophysics. We highlight the recent research progress, discuss challenges, and provide possible future directions in this field.