1. Microcontact Printing
Copyright © 2012 Board of Trustees, University of Illinois. All rights reserved.

2. Objective
You will:
become familiar with techniques used in nanotechnology.
design and make a stamp for patterning a silver surface.
pattern a silver surface by stamping a single layer of molecules onto it.
test the properties of the patterned silver surface.

3. Motivation
Printing large area electronic devices--such as wide-screen televisions.
Printing these electronic devices on flexible materials like plastic.
Microcontact printing can pattern large area electronic devices on flexible materials at a low cost.

4. Nanotechnology Applications
Printed Circuits
Biosensors
Flexible Electronics
Electronic Paper

5. Definition Microcontact printing: Micro contact printing:
1 mm
1 µm
Microcontact printing:
Micro
contact
printing:
transfers ink in a very small pattern from a rubber stamp onto another surface.
is a prefix that means one millionth.
says that two objects are touching.
takes place when a material like ink is transferred by the contact.

6. Microcontact Printing Process
master
mold
PDMS
polymerize, release
stamp
ink solution
ink
inker pad
print
silver substrate
SAM
release
etch

7. Making a Stamp
Master Image
Transparency Mold
Molded PDMS

8. Patterning a Silver Surface
Molded PDMS Stamp
Protective “Ink” Layer
Thin Silver Surface

9. Protective “Ink” Layer
Hexadecane
PDMS Stamp
Protected Regions
Silver Etchant
1-hexadecanethiol
Silver Surface
Sulfur (thiol)

10. Soft Lithography Ultraviolet Light Ultraviolet Light Transparency
Master
Transparency
Master
Spin Coat
Photoresist
Spin Coat
Photoresist
Silicon Wafer
Silicon Wafer
Etch Silicon
Developer:
Remove unexposed
photoresist
Cure PDMS
Developer:
Remove unexposed
photoresist
Stamp
Ink
Etch
Finished Product
Inker Pad
Silicon Wafer
(or other substrate)
Finished Product

11. Soft Lithography Ultraviolet Light Transparency Master Spin Coat
Photoresist
Silicon Wafer
Etch Silicon
Developer:
Remove unexposed
photoresist
Stamp
Ink
Etch
Finished Product
Finished Product
Silicon Wafer
(or other substrate)

12. Microcontact Printing Press

13. Today’s Activity 1. Ink Stamp 2. Stamp silver 3. Etch silver
4. Observe pattern
5. Silver glass