Soret motion of a charged spherical colloid.
Phys Rev Lett 101:10 (2008) 108301
Abstract:
The thermophoretic motion of a charged spherical colloidal particle and its accompanying cloud of counterions and coions in a temperature gradient is studied theoretically. Using the Debye-Hückel approximation, the Soret drift velocity of a weakly charged colloid is calculated analytically. For highly charged colloids, the nonlinear system of electrokinetic equations is solved numerically, and the effects of high surface potential, dielectrophoresis, and convection are examined. Our results are in good agreement with some of the recent experiments on highly charged colloids without using adjustable parameters.Analytic results for the three-sphere swimmer at low Reynolds number.
Phys Rev E Stat Nonlin Soft Matter Phys 77:3 Pt 2 (2008) 036308
Abstract:
The simple model of a low Reynolds number swimmer made from three spheres that are connected by two arms is considered in its general form and analyzed. The swimming velocity, force-velocity response, power consumption, and efficiency of the swimmer are calculated both for general deformations and also for specific model prescriptions. The role of noise and coherence in the stroke cycle is also discussed.A frustrated nanomechanical device powered by the lateral Casimir force
ArXiv 0802.4144 (2008)
Abstract:
The coupling between corrugated surfaces due to the lateral Casimir force is employed to propose a nanoscale mechanical device composed of two racks and a pinion. The noncontact nature of the interaction allows for the system to be made frustrated by choosing the two racks to move in the same direction and forcing the pinion to choose between two opposite directions. This leads to a rich and sensitive phase behavior, which makes the device potentially useful as a mechanical {\em sensor} or {\em amplifier}. The device could also be used to make a mechanical {\em clock} signal of tunable frequency.Mechanical response of a small swimmer driven by conformational transitions.
Phys Rev Lett 100:3 (2008) 038101
Abstract:
A conformation space kinetic model is constructed to drive the deformation cycle of a three-sphere swimmer to achieve propulsion at low Reynolds number. We analyze the effect of an external load on the performance of this kinetic swimmer and show that it depends sensitively on where the force is exerted, so that there is no general force-velocity relation. We discuss how the conformational cycle of such swimmers should be designed to increase their performance in resisting forces applied at specific points.The interfacial behaviour of single poly(N,N-dimethylacrylamide) chains as a function of pH.
Nanotechnology 19:3 (2008) 035505