Biomimetic cilia arrays generate simultaneous pumping and mixing regimes (original) (raw)

Microscale flow propulsion through bioinspired and magnetically actuated artificial cilia

Biomicrofluidics, 2015

Recent advances in microscale flow propulsion through bioinspired artificial cilia provide a promising alternative for lab-on-a-chip applications. However, the ability of actuating artificial cilia to achieve a time-dependent local flow control with high accuracy together with the elegance of full integration into the biocompatible microfluidic platforms remains remote. Driven by this motive, the current work has constructed a series of artificial cilia inside a microchannel to facilitate the time-dependent flow propulsion through artificial cilia actuation with high-speed (>40 Hz) circular beating behavior. The generated flow was quantified using micro-particle image velocimetry and particle tracking with instantaneous net flow velocity of up to 10(1 ) μm/s. Induced flow patterns caused by the tilted conical motion of artificial cilia constitutes efficient fluid propulsion at microscale. This flow phenomenon was further measured and illustrated by examining the induced flow beha...

Magnetically-actuated artificial cilia for microfluidic propulsion

In this paper we quantitatively analyse the performance of magnetically-driven artificial cilia for labon-a-chip applications. The artificial cilia are fabricated using thin polymer films with embedded magnetic nano-particles and their deformation is studied under different external magnetic fields and flows. A coupled magneto-mechanical solid-fluid model that accurately captures the interaction between the magnetic field, cilia and fluid is used to simulate the cilia motion. The elastic and magnetic properties of the cilia are obtained by fitting the results of the computational model to the experimental data. The performance of the artificial cilia with a non-uniform cross-section is characterised using the numerical model for two channel configurations that are of practical importance: an open-loop and a closed-loop channel. We predict that the flow and pressure head generated by the artificial cilia can be as high as 18 microlitres per minute and 3 mm of water, respectively. We also study the effect of metachronal waves on the flow generated and show that the fluid propelled increases drastically compared to synchronously beating cilia, and is unidirectional. This increase is significant even when the phase difference between adjacent cilia is small. The obtained results provide guidelines for the optimal design of magnetically-driven artificial cilia for microfluidic propulsion.

Active micromixer based on artificial cilia

Physics of Fluids, 2007

We propose a design for an active micromixer that is inspired by the motion of ciliated micro-organisms occurring in nature. The conceptual design consists of an array of individually addressable artificial cilia in the form of microactuators covering the channel wall. The microactuators can be set into motion by an external stimulus such as an electric or a magnetic field, inducing either a primary or secondary motion in the surrounding fluid. To validate the concept and to help to design the precise mixer configuration, we developed a computational fluid-structure model. This model is based on a fictitious domain method that couples the microactuator motion to the concomitant fluid flow, fully capturing the mutual fluid-structure interactions. The simulated flow patterns resulting from the motion of single and multiple actuated elements ͑in a microchannel filled with a Newtonian fluid͒ under the action of a time-periodic forcing function are analyzed using dynamical systems theory to quantify the mixing efficiency. The results show that with a proper actuation scheme, two microactuators placed on the same wall of a microchannel can indeed induce effective mixing by chaotic advection; their distance should be small, but collisions should be avoided, and they can be actuated in a rather broad regime around 90°out of phase. Placing actuators on opposite walls also induces exponential stretching in the fluid, but if their length is relatively small, of the order of 20% of the channel height, mixing effectiveness is higher when they are arranged on the same wall.

Fluid propulsion using magnetically-actuated artificial cilia – experiments and simulations

RSC Advances, 2013

We conducted a combined modelling and experimental approach to explore the underlying physical mechanisms responsible for fluid flow caused by magnetically-actuated plate-like artificial cilia. After independently calibrating the elastic and magnetic properties of the cilia, the model predictions are observed to be in excellent agreement with the experimental results. We show that the fluid propelled is due to a combination of asymmetric motion and fluid inertia forces. The asymmetric motion of the cilia and inertial forces contribute equally to the total fluid flow. We have performed a parametric study and found the cilia thickness and magnetic field that should be applied in order to maximise the fluid transport.

Experimental investigation of the flow induced by artificial cilia

Lab on a Chip, 2011

The study of biological flows enjoys a rapidly increasing interest. Research on biomedical flow systems and animal locomotion has reached a high level of maturity and has become a well established topic within the larger field of fluid mechanics. While there are many research groups studying flow problems at moderate to large Reynolds numbers (e.g. cardiovascular fluid mechanics), academic research on biomedical flows at low Reynolds numbers is less commonly found. This fact is unfortunate since low-Reynolds-number flows are highly relevant to medicine and biology in general, and to physiology in particular. In collaboration with medical scientists and biologists, the fluid dynamics community is able to make substantial contributions to these fields. Typical low-Reynolds-number biomedical and biological flow systems may include • flow in the lower airways • cerebrospinal fluid flow • microcirculation and red blood cell transport • flows in the eye and the inner ear (balance sense, hearing) • biomedical microdevices (e.g. filters, pumps, drainages, microrobots) • propulsion and collective behaviour of microorganisms. This Colloquium brings together researchers from groups throughout Europe working on low-Reynolds-number biomedical and biological flows including theoretical, experimental and computational contributions.

Dynamics of Cilia-Based Microfluidic Devices

Journal of Dynamic Systems, Measurement, and Control, 2011

This article models the dynamics of cilia-based devices (soft cantilever-type, vibrating devices that are excited by external vibrations) for mixing and manipulating liquids in microfluidic applications. The main contribution of this article is to develop a model, which shows that liquid sloshing and the added-mass effect play substantial roles in generating large-amplitude motion of the cilia. Additionally, experimental mixing results, with and without cilia, are comparatively evaluated to show more than one order-of-magnitude reduction in the mixing time with the use of cilia.

Nature-inspired microfluidic propulsion using magnetic actuation

Physical Review E, 2009

In this work we mimic the efficient propulsion mechanism of natural cilia by magnetically actuating thin films in a cyclic but non-reciprocating manner. By simultaneously solving the elasto-dynamic, magnetostatic and fluid mechanics equations, we show that the amount of fluid propelled is proportional to the area swept by the cilia. By using the intricate interplay between film magnetization and applied field we are able to generate a pronounced asymmetry and associated flow. We delineate the functional response of the system in terms of three dimensionless parameters that capture the relative contribution of elastic, inertial, viscous and magnetic forces.