A microfluidic approach for fabrication of Janus hydrogel particles with magnetic anisotropy is demonstrated. Using this technique, cells and magnetic beads (MBs) can be separately embedded in one hydrogel particle to maintain optical performance, and reduce the contact between cells and magnetic beads (nano- or submicron-particles). Alginate cell capsules prepared by this method can be easily controlled and manipulated by external magnetic fields and require no specific surface modification. Bio-degradability and super-paramagnetic properties of these hydrogel particles were also demonstrated experimentally.

Optofluidic microcavities are integrated elements of microfluidics that can be explored for a large variety of applications. In this review, we first introduce the physics basis of optical microcavities and microflow control. Then, we describe four types of optofluidic dye lasers developed so far based on both simple and advanced device fabrication technologies. To illustrate the application potential of such devices, we present two types of laser intracavity measurements for chemical solution and single cell analyses. In addition, the possibility of single molecule detection is discussed. All these recent achievements demonstrated the great importance of the topics in biology and several other disciplines.

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The stability of leading-edge vortices (LEVs) on a samara-inspired rotor during steady and unsteady gusty incoming flow was investigated experimentally using direct rotational speed measurements, as well as time-resolved particle image velocimetry (PIV). The blades of the samara-inspired rotor were designed to match the tip-speed ratio, the aspect ratio, and the distribution of the effective angle of attack of samara seeds to utilize LEVs similar to samara seeds. The flow around the blades of the samara-inspired rotor was compared to a reference rotor, which possesses a constant spanwise effective angle of attack, to investigate the influence of the samara-like spanwise effective angle-ofattack distribution on LEV stability. Furthermore, the unsteady performance of the samara-inspired rotor was compared to a generic low-inertia rotor that possesses blades with a constant effective angle of attack less than the stall angle. During steady rotation, the samara-inspired rotor exhibited a stably-attached LEV, while the reference rotor demonstrated unstable LEV shedding. Compared to a generic low-inertia rotor, the samara-inspired rotor demonstrated a relatively stable tip-speed ratio (λ) during the gust. Furthermore, the LEV remained stably-attached on the rotor's blades with a constant normalized circulation during the gust. Finally, the analysis of the LEV stability during the gust using the vorticity transport equation suggests that LEV stability is coupled with constant tipspeed ratio during gusts.