Anisotropic Photonic Microobjects with Dual Stopbands Formed from Single Photonic Dispersion and Their Application for Anticounterfeiting

Janus photonic microobjects have shown great potential in various fields due to their anisotropic shapes and tunable optical properties. Microfluidics is useful for constructing such photonic microobjects. The traditional method of injecting different colloidal photonic streams toward anisotropic multiple stopband photonic microobjects involves complicated and time-consuming procedures. Herein, an easy yet effective approach to fabricate Janus photonic microobjects with dual stopbands from a single stream of photonic components is proposed. A microfluidic device is used to prepare bullet-like, single-stopband photonic microobjects by virtue of the microchannel’s confinement effect. Both the size and shape are readily regulated by adjusting the flow rate of the continuous phase. Under the protection of the desired region of the photonic microobjects with polystyrene (PS) film or silicone tube, the other region is selectively etched to generate a new photonic part. The Janus photonic microobjects with dual stopbands are achieved thereby. Precision control of the protection position of the single-stopband photonic microobjects provides the flexibility to achieve photonic microobjects with various segmental combinations. The porous structure at the etched region is conducive to further functionalization, for example, fluorescence performance, by filling polymers. The resultant photonic microobjects with strong information-encoding characteristics are promising in display and anticounterfeiting.