Micro-moulded magnetic artificial cilia for anti-fouling surfaces

Cilia are microscopic hair-like filaments found in nature which can perform such functionalities as swimming, feeding, and particle manipulation [1]. The particle manipulation property of cilia has been extensively studied by the group of prof. Anna Balazs and co-workers using computational modelling [2]. Inspired by these, we propose the use of artificial cilia to create anti-fouling surfaces in man-made applications.
We have fabricated magnetically actuated artificial cilia using an out-of-cleanroom, cost-effective and time-saving method – micro-moulding technology. The moulding process consists of seven steps: (1) moulds featured micro-holes are fabricated using photo-lithography; (2) a mixture composed of a base PDMS + curing agent and iron particles (P-I) is poured onto the mould, followed by a degassing procedure; (3) the top part of P-I which is outside of the micro-holes, is removed; (4) the mould is placed in a uniform magnetic field to align the iron particles; (5) pure base PDMS + curing agent are poured onto the mould, which will form the so-called base for cilia; (6) the liquid-like composition which covers the mould is cured in an oven; (7) the cured P-I – PDMS is peeled off the mould. Finally, we obtain magnetic artificial cilia, which “stand” on a transparent PDMS base (Fig. 2).
Magnetic artificial cilia made with the micro-moulding method can perform a tilted conical movement mimicking the motion of cilia in nature, which is achieved by positioning a rotating magnet underneath the PDMS base. An actuation video can be found on https://www.youtube.com/watch?v=9KVCVMa3Lvk . Our next step is to characterize the particle manipulation capability of our cilia and then to create an anti-fouling surface.