Micro-fluidic actuation using magnetic artificial cilia

Abstract

We demonstrate advanced fluid manipulations using magnetic polymeric artificial cilia on the walls of a microfluidic channel. In nature, cilia are little hairs covering the surface of micro-organisms which enable them to manipulate a fluid on the micro-scale. The asymmetric movement of natural cilia is crucial to obtain a net fluid flow. We have developed a ferromagnetic polymer made from iron nanoparticles and polydimethylsiloxane, and describe a process that can structure the material into high aspect ratio lying artificial cilia with a length of 300 microm. These artificial cilia were actuated with a homogeneous rotating magnetic field (micro(0)H < 50 mT) generated with a compact external electromagnet. An asymmetric movement involving torsion could be created when the cilia were provided with a remanent magnetisation perpendicular to the plane of rotation of the magnetic field vector. The artificial cilia could be actuated in fluid up to a frequency of approximately 50 Hz. In an aqueous solution in a microfluidic chamber we were able to generate rotational as well as translational fluid movements with fluid velocities up to approximately 0.5 mm s(-1).

Artificial cilia fabricated using magnetic fiber drawing generate substantial fluid flow

“…In most of the previously published work on artificial cilia or flagella, a big drawback for real application is that the fabrication techniques adopted are tedious and costly, as they either require microsystem techniques like photolithography (den Toonder et al 2008;Vilfan et al 2010;Fahrni et al 2009;Belardi et al 2011;Khaderi et al 2011), or rely on expensive sacrificial materials (Evans et al 2007). In order to address this issue, our research is aimed at fabricating artificial cilia in a cost-efficient, cleanroom-free manner, while realizing an effective pumping function that can be practically used in lab-on-achip devices.…”

A continuum model for flow induced by metachronal coordination between beating cilia

“…Numerical studies have been performed by Khatavkar et al (2007) and Khaderi et al (2009), showing that electromagnetically driven artificial cilia can induce mixing and pumping. Cilia-like structures of micrometre scale have been built by different groups (see Nonaka et al 2005;Singh, Laibinis & Hatton 2005), but it was only recently that artificial cilia could be synthesized and externally actuated to manipulate fluid on sub-millimetre scales (see den Baltussen et al 2009;Fahrni, Prins & van Ijzendoorn 2009;Oh et al 2009;Hussong et al 2011). A brief overview of experimental work is given by Zhou & Liu (2008).…”

Highly Magneto-Responsive Elastomeric Films Created by a Two-Step Fabrication Process

“…11,12,[21][22][23][24][25] Therefore, this class of magnetic materials opened new opportunities for their utilization in various applications where soft actuators are required such as microfluidic systems or micropumps. 12,21 Indeed, the low elastic modulus of the polymeric matrix allows a direct transfer to the polymeric chains of the forces acting on the magnetic particles under the external field, thus resulting in rapid actuation of flat membranes. However, in order to obtain high deflection values, relatively high magnetic fields should be applied (e.g.…”