Giant nonlinear optical activity of achiral origin in planar metasurfaces with quadratic and cubic nonlinearities

3D chirality is shown to be unnecessary for introducing strong circular dichroism for harmonic generations. Specifically, near-unity circular dichroism for both second-harmonic generation and third-harmonic generations is demonstrated on suitably designed ultrathin plasmonic metasurfaces with only 2D planar chirality. The study opens up new routes for designing chip-type biosensing platform, which may allow for highly sensitive detection of bio- and chemical molecules with weak chirality

INTERNSHIP ARTICLE Droplet Generation in Flow-Focusing Microfluidic Devices for the Creation of Artificial Cells

This paper systematically investigated the effect of flow rate ratios between the water and oil phases, and concentrations of sodium alginate within the water phase, on the generation of droplets and capsules in a microfluidic reactor in order to facilitate artificial cell production within the water phase for biological experiments. Artificial cells, which simulate the processes that occur within organisms in vitro without the use of real tissues, can be made within flow focusing microfluidic chips. However, researchers must first fine tune the systems in which they are made in order for these cells to be generated. These tests will help make artificial cells more efficient to fabricate within microfluidic systems. Droplets were formed by the emulsification of water in a continuous oil phase. Capsules were formed through a reaction of sodium alginate, carried in the water phase, and calcium ions, carried in the oil phase, to create a cross-linked membrane of calcium alginate surrounding a droplet. An increase in the flow rate of water had a positive correlation on the size of the droplets created, and an increase in the flow rate of oil had a negative correlation. Changes to the flow rates of the continuous oil phase affected the system more than changes to the flow rates of the dispersive water phase. In addition, high concentrations of sodium alginate within the dispersive phase increases the stability of the droplet formation, as well as the stability of the capsules formed within the microfluidic device