Microfluidics
Homework Set 1
Due Tuesday, December 9, 2008
1.
Go to a technical journal (specific to your profession if possible) and find a recent paper in
which a microfluidic device was fabricated or utilized. Indicate the dimensions of the
channels/features on the device, and provide a brief description of its function. Submit a
copy of the article.
Note: If you are not sure where to look for such an article, let me suggest Analytical
Chemistry, Nano Letters, or ACS Nano, journals available online through Logan Library. Go
to the library’s website, click on the “Databases A to Z” link, and click on “ACS Journals
and Magazines” to find these online journals.
2.
Let’s do a simple calculation to give you some idea of the volumes and surface areas
associated with particular feature sizes. Below is a diagram depicting how a sample “plug” is
isolated and separated at the intersection of perpendicular microchannels.
Sample
Waste
+
-
Injection
+
+
-
-
Sample Plug
Separation
a. Calculate the volume of such a sample plug if the channels are all 90 μm wide and 10 μm
tall. You can assume that the channel walls are flat and that the sample plug does not
diffuse longitudinally.
b. Still assuming no longitudinal diffusion of the sample plug, calculate the total surface
area over which the sides of the plug are in contact with the channel walls and report this
surface:volume ratio. Realize that only four (4) sides of the plug are actually in contact
with the channel walls.
c. Compare the surface:volume ratio in part b with that of a 1 cm cube of fluid.
Useful Unit Conversions and Prefixes:
1 m = 100 cm = 1000 mm = 1 x 106 μm
1 mL = 1 cm3
Mirco (μ) = 1 x 10−6
Nano (n) = 1 x 10−9
Pico (p) = 1 x 10−12
Femto (f) = 1 x 10−15