title: Rheological Properties of Viscoelastic Drops on Superamphiphobic Substrates.
abstract: The rheological properties of microliter sized drops of polymer solutions were investigated using measurements of their mechanical vibrational response. Drops were suspended on superamphiphobic substrates and vibrated by the application of a short mechanical impulse. Surface vibrations were monitored by refracting laser light through the drops and focusing the refracted light onto the surface of a photodiode. Time dependent variations in the photodiode output were Fourier transformed to obtain the frequency and spectral width of the mechanical resonances of the drops. These quantities were related to the frequency dependent shear storage and loss moduli (G' and G″, respectively) using a simple theoretical model. The resulting rheological properties were found to be in agreement with microrheology measurements of the same solutions. Drop vibration therefore provides a fast and accurate method of quantifying the rheological properties of single drops.
authors.affiliation: School of Physics & Astronomy, University of Nottingham , University Park, Nottingham NG7 2RD, U.K.
authors.forename: Victoria C
authors.initials: VC
authors.lastname: Harrold
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Maxime
authors.initials: M
authors.lastname: Paven
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Doris
authors.initials: D
authors.lastname: Vollmer
authors.affiliation: School of Physics & Astronomy, University of Nottingham , University Park, Nottingham NG7 2RD, U.K.
authors.forename: James S
authors.initials: JS
authors.lastname: Sharp