title: Inkjet printing and release of monodisperse liquid crystal droplets from solid surfaces.
abstract: Recently, liquid crystal (LC) droplets in aqueous solutions have become a new platform for chemical and biological sensing applications. In this work, we present a two-step method to generate monodisperse LC droplets in aqueous solutions for sensing applications. In the first step, we exploit inkjet printing to dispense uniform LC droplets on a solid surface. Uniform LC droplets, ranging from 35 to 136 μm in diameter, can be prepared by printing multiple times on the same spot. In the second step, we flush the LC droplets with a stream of aqueous solution in an open rectangular channel. Factors that determine the polydispersity of the LC droplets include flow rates and surface wettability. Under appropriate experimental conditions (i.e., when the surface is glass and the flow rate is sufficiently high), the LC droplets can be lifted off completely and carried away by the solution, forming free LC droplets (15-62 μm in diameter). These free LC droplets can respond to a chemical reaction and change their optical textures uniformly.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore.
authors.forename: Vera Joanne
authors.initials: VJ
authors.lastname: Aliño
authors.forename: Kun Xiang
authors.initials: KX
authors.lastname: Tay
authors.forename: Saif A
authors.initials: SA
authors.lastname: Khan
authors.forename: Kun-Lin
authors.initials: KL
authors.lastname: Yang
mesh_terms: D007281:Ink; D050866:Liquid Crystals / Q000737:chemistry*; D010316:Particle Size; D011327:Printing; D013499:Surface Properties; D017155:Wettability