Magnetic artificial cilia; Study of formation mechanism in an external magnetic field

Artificial cilia are nature inspired devices with wide range of applications in microfluidic systems as sensors or actuators. Vast verity of methods are introduced for fabrication of these devices such as soft lithography, sacrificial template method, track-etched membrane, self assembly, printing method and field directed assembly. Recently, there has been increasing attentions on fabrication of magnetic artificial cilia due to ease of actuation and signal generation by magnetic field. In this scope, field directed assembly of magnetic nanocomposites in the form of artificial cilia is a novel method with remarkable advantages. On the other hand, presence of several affecting interactions such as magnetic, solvent-cilia, cilia-cilia, cilia-ground and etc, makes an ambiguous understanding about the mechanism of formation of magnetic cilia in external magnetic field. In the present study we have investigated the mechanism by design of novel experiment to track the cilia formation in different steps. Some factors in the experiments such as field gradient, nanoparticle concentration, polymer concentration were regarded as variables and their effects on mechanism and morphology of final structures were studied. Five determining steps were distinguished in the formation mechanism i.e., dipolar assembly of magnetic nanoparticles, immigration of magnetic assemblies, lateral collapsing of the assemblies, ground collapsing of the assemblies and shrinkage of polymer matrices. This study extends researchers insight for the future studies in the field of magnetic artificial cilia.

Keywords:

Artificial cilia , Magnetic nanoparticles , Field directed assembly , Mechanism of formation