title: Chirality Detection Using Nematic Liquid Crystal Droplets on Anisotropic Surfaces.
abstract: Nematic liquid crystals (NLCs) form helical macroscopic structures through chiral induction when doped with chiral species. We describe a very simple, though highly sensitive method for determination of handedness and pitch of the induced twist in the case of very weak twisting powers of such chiral dopants. A tiny drop-typically less than 10 nL-of the chiral doped NLC is placed on a plate promoting a uniform planar surface anchoring of the liquid crystal director. At the curved NLC-air interface the anchoring is homeotropic and in the sessile droplets we get a locally twisted hybrid director structure with a disclination line extending across the droplet. The configuration of the disclination line (S-like or backwards S-like) reveals the sign of twisting power and extremely large pitch values in the range of 10 mm can easily be measured. We demonstrate the method using the standard NLC 4-cyano-4'-pentylbiphenyl (5CB), weakly doped with the chiral material 2-hydroxy-2-phenylacetic acid (mandelic acid).
authors.affiliation: Microtechnology and Nanoscience, Chalmers University of Technology , 412 96 Göteborg Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Rudquist
authors.affiliation: Institute of Physical Chemistry, University of Stuttgart , 70569 Stuttgart, Germany.
authors.forename: Clarissa F
authors.initials: CF
authors.lastname: Dietrich
authors.affiliation: Max Planck Institute of Intelligent Systems , 70569 Stuttgart, Germany.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Mark
authors.affiliation: Institute of Physical Chemistry, University of Stuttgart , 70569 Stuttgart, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Giesselmann