Mme Maria Michiko Alcanzare, chercheur au Département de Physique Appliquée à l’Ecole des Sciences de l'Université Aalto (Helsinki, Finlande), donnera un séminaire le Mercredi 25 Novembre 2015 à 10h dans la salle de Conférences d’XLIM (Accueil café à partir de 9h30). Son séminaire s’intitule “Directed motion of externally driven helical swimmers in the nanoscale”.
Note pour les doctorants : pensez à vous inscrire sur la liste d’appel lors du séminaire afin de faire valider votre participation auprès de l’école doctorale ED521 !
Abstract. Controlled nanoscale motion in a fluid environment is one of the most ambitious challenges in nanoscience. Nanomachines that are able to transform energy to mechanical work have been fabricated to perform a series of tasks such as transporting drug or genetic material in cells, fluid mixing that accelerates chemical reactions and cargo transport in microfluidic chips. We focus on directing, controlling and optimizing the movement of an externally driven nanohelical swimmer. Helical particles have coupled translational and rotational motion therefore propulsive motion can be performed by applying an external torque. The difficulty in achieving directed and controlled motion in the nanoscale lies mainly in overcoming the thermal effects which may dominate the locomotive behaviour of the helical particle. We study the effects of shapes, the pitch angles and helical turns, and the viscosity of the fluid that result in optimal propulsive motion by using a hybrid method that utilizes the full hydrodynamic interactions.
In this talk, I will be discussing the hybrid lattice Boltzmann - molecular dynamics (LBMD) multiscale method, and the main results of the study. Directed motion in the presence of thermal fluctuations requires external torques that are significantly greater than the thermal energy of the fluid. The increase in the length by increasing the helical turns of the chiral particle adds to the stability in its directed motion but this also increases the hydrodynamic drag. Therefore a balance between attaining stability and minimizing the hydrodynamic drag is necessary in achieving optimal propulsion and efficiency. Current magnetic helical particles are micronsized hence our results provide insight in fabricating optimal nanohelical swimmers and the external torque strengths for which controlled and directed motion is possible.
Venez nombreux !
Contact du séminaire : Arnaud Videcoq (arnaud.videcoq@unilim.fr) / seminaires@xlim.fr