To characterize the microfluidic pumping capabilities of the artificial cilia, we incorporate the cilia inside a PDMS microchannel loop and analyze the flow in produces. We vary important parameters such as the cilia width, spacing, number of rows and channel dimensions and establish its influence on the pumping efficiency. We observe low pumping rates at very high and very low operating frequencies, and establish an optimum operating frequency for maximized pumping efficiency.
Further, we demonstrate the use of such cilia for microfluidic mixing. For this, we use a PDMS Y-channel with cilia on its bottom wall. Two fluids dyed with different fluorescent colors are introduced into the two inlet channels. And the ability of the cilia to mix the two streams of fluid is characterized by imaging the fluorescent intensity of the fluid stream downstream from the cilia. Again, we show the dependence of mixing efficiency on several parameters of the system.
We also demonstrate particle capture with these artificial cilia. To do this, we functionalize the cilia with streptavidin protein, and introduce particles coated with biotin into the microchannel. The cilia is then oscillated so as to produce mixing in the microchannel. The mixing effect increases the probability of particles coming in contact with the cilia. The biotin coated particles stick to the cilia when they come into contact. This demonstrates capture of particles in a microfluidic channel. These microfluidic functions find varied application in many lab on a chip devices where active fluid transport is needed.