Concepedia

Artificial cilia for active micro-fluidic mixing

Jaap M. J. den Toonder, Femke Bos, Laura Filippini, M. F. Gillies, Judith de Goede, Titie Mol, Mireille Reijme, Wim Talen, H. T. A. Wilderbeek, Vinayak Khatavkar,

Lab on a Chip · 2008 · 295 citations · 23 references

DOI

TL;DR

Lab‑on‑chip devices miniaturize complete (bio‑)chemical analysis laboratories, requiring fluid manipulation in sub‑millimetre channels and sub‑microlitre chambers, yet achieving effective mixing is difficult because turbulence is nearly impossible to generate. The study proposes an active micro‑fluidic mixing concept inspired by the oscillating cilia of microorganisms. Artificial cilia were fabricated from electro‑statically actuated polymer structures and integrated into a micro‑fluidic channel to realize the proposed mixing concept. Experiments demonstrate that the artificial cilia produce fluid velocities up to 0.6 mm s⁻¹, achieve highly efficient mixing with specially designed geometries, and can be actively controlled electrically, offering promising applications in micro‑fluidic devices.

Abstract

In lab-on-chip devices, on which complete (bio-)chemical analysis laboratories are miniaturized and integrated, it is essential to manipulate fluids in sub-millimetre channels and sub-microlitre chambers. A special challenge in these small micro-fluidic systems is to create good mixing flows, since it is almost impossible to generate turbulence. We propose an active micro-fluidic mixing concept inspired by nature, namely by micro-organisms that swim through a liquid by oscillating microscopic hairs, cilia, that cover their surface. We have fabricated artificial cilia consisting of electro-statically actuated polymer structures, and have integrated these in a micro-fluidic channel. Flow visualization experiments show that the cilia can generate substantial fluid velocities, up to 0.6 mm s−1. In addition, very efficient mixing is obtained using specially designed geometrical cilia configurations in a micro-channel. Since the artificial cilia can be actively controlled using electrical signals, they have exciting applications in micro-fluidic devices.