title: Interface shear microrheometer with an optically driven oscillating probe particle.
abstract: We report the first experimental demonstration of an active interfacial shear microrheometer (ISMR) that uses a particle trapped by oscillating optical tweezers (OT) to probe the shear modulus G(s)(*)(ω) of a gas/liquid interface. The most significant advantages of the oscillating OT in a rheology study are: (1) very high sensitivity compared to other active microrheology methods and (2) the ability to measure both the real and imaginary components of the complex shear modulus without relying on the use of Kramers-Kronig relation, which can be problematic at low frequencies for most of the passive methods. We demonstrate the utilities of our ISMR in two case studies: (1) a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine monolayer and (2) a composite of poly(styrene sulfonate) and dioctadecyldimethylammonium at the air/water interface in regimes where no other active instruments can explore.
authors.affiliation: Department of Physics, KAIST, Daejeon 305-701, South Korea. cypark0411@gmail.com
authors.forename: Chang Young
authors.initials: CY
authors.lastname: Park
authors.forename: H Daniel
authors.initials: HD
authors.lastname: Ou-Yang
authors.forename: Mahn Won
authors.initials: MW
authors.lastname: Kim
mesh_terms: D000388:Air; D004573:Electrolytes / Q000737:chemistry; D005246:Feedback; D008055:Lipids / Q000737:chemistry; D055616:Microtechnology / Q000295:instrumentation*; D052898:Optical Tweezers; D011108:Polymers / Q000737:chemistry; D012212:Rheology / Q000295:instrumentation*; D012995:Solubility; D014867:Water / Q000737:chemistry
chemical_list: D004573:Electrolytes; D008055:Lipids; D011108:Polymers; D014867:Water