Upon invitation by the editors we contributed a chapter to a book on artificial cilia, published by the renowned RSC Publishing house. In our chapter we present detailed measurements of the fluid flow of a single magnetically driven artificial cilium, of a row of cilia, as well as a two dimensional ciliated field. We compare experimental measurements with a theoretical model (multipole expansion, as well as simulation). Both the spatial dependence, as well as the magnitude of flows shows good agreement.
COBISS.SI-ID: 26814759
In collaboration with the department of Material Synthesis at IJS and the start-up company Nanos Scientificae we fabricated, optimized and demonstrated the usage of superparamagnetic microgears for use in microfluidic applications. The gears are driven by a rotating magnetic field. At low frequencies they follow the rotation of the field up to a critical frequency (the optimal point of operation lies just below this frequency) at which phase slippage occurs and the angular velocity drops. At higher frequencies the rotation rate increases again. By analyzing the frequency response we showed that the torque on microgears is a consequence of anisotropic susceptibility at low frequencies and relaxation phenomena at high frequencies.
COBISS.SI-ID: 27896103
In the paper we investigated the hydrodynamic synchronization of autonomous oscillators. We have shown that two particles in general synchronize in-phase and that the level of synchronization is stronger when the particles are arranged parallel to the direction of oscillations than perpendicular. Our study shows that self-oscillating particles can act as a model system for synchronization between biological cilia. Although several model systems for hydrodynamic synchronization had been published previously, ours was the first to use truly autonomous microscopic oscillators. The results were published in Physical Review E (Rapid Communication), where the paper was also highlighted as Editor's suggestion.
COBISS.SI-ID: 28452391
We studied experimentally and theoretically the formation of dynamically self-assembled colloidal clusters in a rotating magnetic field. When a system of superparamagnetic particles is subject to a precessing magnetic field, they dynamically assemble into a lattice of rotating clusters under certain conditions. Using a continuum theory we explained the shape and size of the vortices and showed that their rotation is caused both by magnetic relaxation and the formation of short-lived pairs and chains inside the cluster.
COBISS.SI-ID: 29511463
We showed that colloidal wheels, consisting of superparamagnetic particles, roll in skewed direction in a magnetic field that is rotating in a tilted plane. The motion is non-reciprocal as the wheel does not backtrace its trajectory when the field rotation is reversed. We found an explanation for this phenomenon in the anisotropic nature of the mobility tensor in the presence of a no-slip boundary, which leads to an induced chirality of a system that is originally symmetric.
COBISS.SI-ID: 29974311