Shape control of colloidal crystals by microfluidics and their applications to optical functional materials

胶体晶体是一种单分散粒子的三维周期性阵列，在可能的应用方面受到了极大的关注，特别是作为光子晶体。胶体晶体通常是在衬底上制备的，薄膜的形状限制了这些晶体在许多应用中的应用。在这项工作中，我们成功地利用微流控技术制备了各种形状的胶体晶体，如贝壳、纤维和大薄膜。我们证明了凝胶固定的胶体晶体外壳在微胶囊中具有潜在的应用价值，可以通过布拉格衍射波长或衍射色来监测胶囊内外的变化。

Colloidal crystals, three-dimensional periodic arrays of monodisperse particles, have received considerable attention with respect to the possible application, particularly as photonic crystals. The colloidal crystals are conventionally fabricated on the substrate, and the film shape limits the utility of these crystals for many applications. In this work, we have succeeded in fabricating colloidal crystals in various shapes such as shells, fibers, and large films by microfluidic techniques. We demonstrated that the gel-immobilized colloidal crystal shells are potentially useful for microcapsules that can monitor changes inside and outside the capsules through the Bragg diffraction wavelength or diffraction color.