Microfluidics integration of aperiodic plasmonic arrays for spatial-spectral optical detection

Optofluidic lenses with horizontal-to-vertical aspect ratios in the subunit regime

Elliptical optofluidic lenses can provide tunable optical parameters in different optical planes. This tunability is achieved through modifications to the aspect ratio (AR). We present an optofluidic lens with a subunit AR. In our experimental analysis, we alter the shape of the microdroplet and observe a 10% reduction in the AR on applying a high voltage across the microdroplet. In our theoretical analysis, we observe improved tunability of focal length, longitudinal spherical aberration, and beam cone angle in the subunit AR regime compared to the superunit AR regime. We ultimately test and characterize the optofluidic lens in an imaging application.

Plasmonic reflection color filters with metallic random nanostructures

We develop reflective color filters with randomly distributed nanodisks and nanoholes fabricated with hydrogen silsesquioxane and Ag films on silicon substrate. They exhibit high resolution, angle-independence and easily up-scalable fabrication, which are the most important factors for color filters for industrial applications. We uncover the underlying mechanism after systematically analyzing the localized surface plasmon polariton coupling in the electric-field distribution. The agreement of the experimental results with those from the simulation indicates that tunable colors across the visible spectrum can be obtained by simply varying the diameter of the nanodisks, promoting their applications.

Deformability-Based Electrokinetic Particle Separation

Deformability is an effective property that can be used in the separation of colloidal particles and cells. In this study, a microfluidic device is proposed and tested numerically for the sorting of deformable particles of various degrees. The separation process is numerically investigated by a direct numerical simulation of the fluid–particle–electric field interactions with an arbitrary Lagrangian–Eulerian finite-element method. The separation performance is investigated with the shear modulus of particles, the strength of the applied electric field, and the design of the contracted microfluidic devices as the main parameters. The results show that the particles with different shear moduli take different shapes and trajectories when passing through a microchannel contraction, enabling the separation of particles based on their difference in deformability.

Fabrication of metallic nanopatterns with ultrasmooth surface on various substrates through lift-off and transfer process

The smooth surface of the metallic nanostructure is essential for the propagation of surface plasmon polaritons. In this paper, we present a novel method to fabricate the metallic nanopatterns with ultra-smooth surface on various substrates. By using a silica film as the sacrificial layer, we show that the prefabricated metallic nanopatterns produced by electron beam lithography and film deposition can be hydrolyzed and transferred onto a designated substrate. The ultra-smooth surface morphology of nanopatterns has been characterized and verified by scanning electron microscopy and atomic force microscopy. More importantly, we demonstrate that this method can successfully produce a variety of nanostructures with high product yield, even onto the uneven substrate. The results indicate that our proposed method is a promising and versatile means to fabricate multiplicate smooth metallic nanostructure on various substrates for the application of nanophotonic devices.