Jaap den Toonder

Abstract: Microfluidic applications such as point-of-care devices, organ-on-chip platforms, or biomedical implants, require the precise control of fluid flow to achieve pumping and mixing. In the current practice, this is done by connecting external pumps to these devices by tubing. This solution is bulky, it is user-unfriendly, and it offers only limited flow control.

We have developed an innovative solution that is based on the integration of magnetic nano- or microactuators in microfluidic devices. The idea is inspired by so-called cilia found in nature. Cilia are hair-like biological microstructures that exhibit oscillatory motion and, in this way, can transport fluids, particles and cells. For example, the inner walls of our lungs are covered with cilia that, by oscillating, move mucus out of our airways. Similar to biological cilia, our magnetic “artificial cilia” can generate fluid pumping, mix fluids, and transport particles in microfluidic devices. This offers the big advantage of tubeless and wireless pumping: the magnetic actuation can be achieved by external (electro)magnets for which no connections with the microfluidic device are needed. Moreover, the motion of the artificial cilia can be easily changed by adapting the magnetic field. This makes this approach compact, easy to use, and flexible.

We have realized magnetic artificial cilia using flexible polymer materials containing magnetic micro- or nanoparticles. Using various fabrication approaches, the size (length/radius) of our cilia can range between 9 μm/0.35 μm, to 350 μm/50 μm. By varying the magnetic field, we can let them rotate, realize whip-like motions, and even induce collective wave-like motion. In this way, the cilia can generate controlled microfluid flow, mixing, and particle transportation. Beyond these applications, the magnetic artificial cilia can be used for anti-biofouling and even magnetic flow sensing.

In this talk, I will discuss the materials we use to make the artificial cilia, explain the various cilia fabrication approaches we have developed, and demonstrate their motion, as well as the achieved microfluidic control, particle manipulation, and anti-biofouling.