Lanthanide nanophosphor species and microfluidic devices used to generate MRBLEs. (A) Photograph showing vials of YVO4:Eu, YVO4:Sm, YVO4:Dy, LaPO4:CeTb, and YVO4:Tm excited by 305 nm light from a handheld UV lamp. (B) Normalized emission spectra for YVO4:Eu, YVO4:Sm, YVO4:Dy, LaPO4:CeTb, and YVO4:Tm LNs. All LNs were excited at 285 nm except for LaPO4:CeTb, which was excited at 275 nm. (C) Photograph of microfluidic bead synthesizer device used for MRBLE production. (D) Cartoon schematic showing bead synthesizer device modules. (E) False color image showing monodisperse microspheres from a 551 MRBLE code set.