Lina Huang

Integration of plasmonic trapping in a microfluidic environment

Near field generated by plasmonic structures has recently been proposed to trap small objects. We report the first integration of plasmonic trapping with microfluidics for lab-on-a-chip applications. A three-layer plasmo-microfluidic chip is used to demonstrate the trapping of polystyrene spheres and yeast cells. This technique enables cell immobilization without the complex optics required for conventional optical tweezers. The benefits of such devices are optical simplicity, low power consumption and compactness; they have great potential for implementing novel functionalities for advanced manipulations and analytics in lab-on-a-chip applications.

Reversal of the optical force in a plasmonic trap

We study in detail the optical forces generated by a plasmonic trap on a plasmonic nanoparticle. The permittivity of the trapped particle is tuned using a Drude model. The interplay between the plasmon resonances of the trap and of the particle can produce different regimes leading to attractive or repulsive forces. Hence a particle will be trapped or repulsed depending on its permittivity. Such a physical system should provide new functionalities for lab-on-the-chip applications.

Integration of plasmonic optical traps in microfluidics

We study the integration of plasmonic traps with microfluidic channels. Plasmonic traps are optical traps that use the evanescent field generated by metallic nanostructures at their plasmon resonance to trap small objects. Contrary to conventional - far-field - traps, plasmonic traps do not require complex optics, as the trapping potential is solely determined by the near-field generated by the nanostructure. This work includes the theoretical study of the trapping potential and its relation to the plasmon resonance; the fabrication of plasmonic traps using electron-beam lithography; the integration with PDMS microchannels; and the statistical analysis of small objects trapped in the structure.

Distance-controlled scattering in a plasmonic trap

Light scattered by a dielectric object when it is trapped in the field of a plasmonic nanostructure is studied theoretically and experimentally using both dielectric spheres and S. cerevisiae cells. A dramatic enhancement of the scattered light is observed for short separation distances between scatterer and plasmonic trap. It is shown that this effect can serve to selectively image cells after their immobilization and distinguish them from a turbid background. The high sensitivity of the scattered light to the separation distance and lateral displacement also provides additional insights in the configuration of the cell within the trap.

Analysis of optical forces in plasmonic traps

We study the optical forces in plasmonic systems and show how they depend on the metals used in the experiment. The incorporation of plasmonic traps in a microfluidic environment provides new functionalities for lab-on-the-chip applications.

Plasmonic Trapping for Nanoscale Analysis in Lab-on-the-Chip Applications

We study the optical forces in plasmonic systems and show how they depend on the metals used in the experiment. The incorporation of plasmonic traps in a microfluidic environment provides new functionalities for lab-on-the-chip applications.