|
Microcontact Printing
The basic steps for creating a stamp for microcontact printing are shown in figure 1 at the right. A silicone
rubber, such as Dow Corning's Sylgard 184, is cast uncured onto a surface which has the features one
wants to reproduce. The silicone conforms to the features on the master down to a scale of at least
tens of nanometers. After curing, the stamp is peeled off the master, and can then be "inked" with
the molecules to be stamped. Stamping is achieved by simple placing the inked stamp on a surface. The
ink molecules transfer to the surface with the pattern of the stamp.
Figure 2 is a picture of a small silicone stamp created from a diffraction grating master. The rainbow
colors seen near the top of the stamp is caused by this diffraction grating now embossed on the stamp.
Stamping molecules
After the stamp is made, it can be inked with the molecules to be stamped. This can be done by simply
dipping the stamp into a solution containing the molecules. After the stamp is removed from the solution,
the excess liquid is blown away with compressed air. It is now covered with a very thin layer of the ink
molecules. When the inked stamp is placed on a surface, the ink molecules are transferred to the surface
everywhere the stamp is touching.
An example of a stamped pattern is shown in figure 3. Lines composed of tristearin can be seen
on the surface of the mineral mica.
We are using microcontact printing to study how certain types of
molecules interact with surfaces at a molecular scale.
Experimental details
If you are interested in the nitty gritty details of microcontact printing, you can look here
Contact info:
Srin Manne
Physics Dept
PAS 575
520-626-5305
smanne@physics.arizona.edu
|
Figure 1. Basic steps for microcontact printing
 |
Figure 2. A small stamp created from a 3 micron pitch linear grating master
 |
Figure 3. A pattern of lines composed of molecules of tristearin created
from a 3 micron pitch linear grating stamp which was immersed in a solution containing tristearin
molecules. The lines are only ~3 nm tall, about the length of a tristearin molecule. This image was
taken by an atomic force microscope.
 |
|
|
