title: Photonic crystal beads from gravity-driven microfluidics.
abstract: This Letter reports a simple method for the mass production of 3D colloidal photonic crystal beads (PCBs) by using a gravity-driven microfluidic device and online droplet drying method. Compared to traditional methods, the droplet templates of the PCBs are generated by using the ultrastable gravity as the driving force for the microfluidics, thus the PCBs are formed with minimal polydispersity. Moreover, drying of the droplet templates is integrated into the production process, and the nanoparticles in the droplets self-assemble online. Overall, this process results in PCBs with good morphology, low polydispersity, brilliant structural colors, and narrow stop bands. PCBs could be bulk generated by this process for many practical applications, such as multiplex-encoded assays and the construction of novel optical materials.
authors.affiliation: State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China.
authors.forename: Hongcheng
authors.initials: H
authors.lastname: Gu
authors.forename: Fei
authors.initials: F
authors.lastname: Rong
authors.forename: Baocheng
authors.initials: B
authors.lastname: Tang
authors.forename: Yuanjin
authors.initials: Y
authors.lastname: Zhao
authors.forename: Degang
authors.initials: D
authors.lastname: Fu
authors.forename: Zhongze
authors.initials: Z
authors.lastname: Gu
mesh_terms: D006112:Gravitation; D013058:Mass Spectrometry; D044085:Microfluidics / Q000379:methods*; D017785:Photons