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Viscosity Dependent Liquid Slip At Molecularly Smooth Hydrophobic Surfaces, Sean P. Mcbride, Bruce M. Law
Viscosity Dependent Liquid Slip At Molecularly Smooth Hydrophobic Surfaces, Sean P. Mcbride, Bruce M. Law
Dr. Sean P. McBride
Colloidal probe atomic force microscopy is used to study the slip behavior of 18 Newtonian liquids from two homologous series, the n-alkanes and n-alcohols, at molecularly smooth hydrophobic n-hexadecyltrichlorosilane coated surfaces. We find that the slip behavior is governed by the bulk viscosity η of the liquid, specifically, the slip length b∼ηx with x∼0.33. Additionally, the slip length was found to be shear rate independent, validating the use of Vinogradova slip theory in this work.
Improved In Situ Spring Constant Calibration For Colloidal Probe Atomic Force Microscopy, Sean P. Mcbride, Bruce M. Law
Improved In Situ Spring Constant Calibration For Colloidal Probe Atomic Force Microscopy, Sean P. Mcbride, Bruce M. Law
Dr. Sean P. McBride
In colloidal probe atomic force microscopy (AFM) surface forces cannot be measured without an accurate determination of the cantilever spring constant. The effective spring constant k depends upon the cantilever geometry and therefore should be measured in situ; additionally, k may be coupled to other measurement parameters. For example, colloidal probe AFM is frequently used to measure the slip length b at solid/liquid boundaries by comparing the measured hydrodynamic force with Vinogradova slip theory (V-theory). However, in this measurement k and b are coupled, hence, b cannot be accurately determined without knowing k to high precision. In this paper, a …
Influence Of Line Tension On Spherical Colloidal Particles At Liquid-Vapor Interfaces, Sean P. Mcbride, Bruce M. Law
Influence Of Line Tension On Spherical Colloidal Particles At Liquid-Vapor Interfaces, Sean P. Mcbride, Bruce M. Law
Dr. Sean P. McBride
Atomic force microscopy (AFM) imaging of isolated submicron dodecyltrichlorosilane coated silica spheres, immobilized at the liquid polystyrene- (PS-) air interface at the PS glass transition temperature, Tg , allows for determination of the contact angle θ versus particle radius R . At Tg , all θ versus R measurements are well described by the modified Young’s equation for a line tension τ=0.93 nN . The AFM measurements are also consistent with a minimum contact angle θmin and minimum radius Rmin , below which single isolated silica spheres cannot exist at the PS-air interface.
Long Reach Cantilevers For Sub-Cellular Force Measurements, Govind Paneru, Prem S. Thapa, Sean P. Mcbride
Long Reach Cantilevers For Sub-Cellular Force Measurements, Govind Paneru, Prem S. Thapa, Sean P. Mcbride
Dr. Sean P. McBride
Maneuverable, high aspect ratio poly 3-4 ethylene dioxythiophene (PEDOT) fibers are fabricated for use as cellular force probes that can interface with individual pseudopod adhesive contact sites without forming unintentional secondary contacts to the cell. The straight fibers have lengths between 5 and 40 μm and spring constants in the 0.07-23.2 nN μm-1 range. The spring constants of these fibers were measured directly using an atomic force microscope (AFM). These AFM measurements corroborate determinations based on the transverse vibrational resonance frequencies of the fibers, which is a more convenient method. These fibers are employed to characterize the time dependent forces …