Dip-pen nanolithography (DPN) is a direct-write nanolithography technique that uses an atomic force microscope (AFM) tip coated with "ink" to deposit molecules on a surface with nanoscale precision. The deposition rate can be precisely controlled, allowing for reliable patterning of biomolecules and other materials in ambient conditions without exposure to harsh chemicals or radiation. Factors like temperature, humidity, ink-substrate interactions, and meniscus formation influence the transport of ink molecules during DPN. Current applications include creating ultra-high density arrays of DNA and proteins for biosensing, while future directions may involve parallel arrays and automated systems.

1. https://giki.edu.pk/mtme2023/

2. An Introduction to
Dip-Pen Nanolithography

3. What is DPN?
 Direct-write patterning technique based on AFM
scanning probe technology
 AFM tip is coated with “ink” and used to write on
surface
 Very reliable bottom-up process (ink deposition rate
can be precisely controlled)

4. What is DPN?
https://www.youtube.com/watch?v=EgGBfHYMNMY
https://www.youtube.com/watch?v=Kif_Ed92KcE

5. What is DPN? (continued)
 Compatible with both hard and soft matter
on lengthscales below 100 nm
 Capable of depositing arrays of
biomolecules on various materials (metals,
semiconductors, functionalized surfaces)
 Biomolecules can be directly deposited on
the surface in ambient temperature, no
exposure to etchants, electron beams, or
radiation

6. Advantages of DPN
Resolution - 15nm
Direct write so only where you want and
what you want
Based on AFM - can write and see
Ambient conditions
1-octadecanethiol (ODT) and 16-mercaptohexadecanoic acid
(MHA) monolayers deposited onto a gold substrate

7. Ink Theory (continued)
The influence of temperature and humidity on the growth rates of 1-
octadecanethiol (ODT) and 16-mercaptohexadecanoic acid (MHA)
monolayers deposited onto a gold substrate has been systematically
studied in the context of dip-pen nanolithography (DPN) experiments. By
analyzing a statistically meaningful data set, we conclude that for both
inks the deposition rate increases with increasing temperature, and that
this temperature dependence is strongly affected by relative humidity,
chemical nature of the ink and substrate, and writing speed. We attribute
these observations to the different solubilities of the ink molecules in
water (both the water in the meniscus and on the cantilever walls). In
addition, we report a set of experiments that demonstrate meniscus
formation even at 0% relative humidity due to residual water that moves
to the point of contact between tip and sample
https://www.researchgate.net/publication/231633194_Dip-
Pen_Nanolithography_What_Controls_Ink_Transport

8. Ink Theory (continued)
Ink-substrate combinations
Tip-substrate molecular transport
Chemical makeup and purity (ink and surface)
Shape of tip
Distribution of ink on tip
Temperature
Humidity of surroundings
Solubility of ink

9. Advantages continued
 More than one layer
 Can work with multiple “inks” at once
 Organic and inorganic inks
 Bottom-up and top-down

10. Limitations
 Size of the molecule should be small than the tip size.
 Substrate surface should be clean and leveled.
 Solvent should not remain on surface.
 There should be no external interference.

11. Ink Theory
 Inks: small organic molecules, organic and biological
polymers, colloidal particles, metals ions

12. Ink Theory (continued)
 Water meniscus from ambient moisture
 Humidity controlled box

13. Current Applications
DPN is specially advantageous to
biomolecular manipulation
DNA and protein arrays are being
fabricated as detection chips
DPN resolution is four to five orders
of magnitude greater than other
lithographic techniques: ultra-high
density nanoarrays

14. Obstacles
 Most are currently being addressed
 Speed
 Matching inks to substrates, correct conditions
 Smooth surfaces to work on
 Turning the write head on/off at will

15. Future Applications
 Parallel arrays
 Passive probe array
 Duplicate a pattern multiple times
 Independent control of each probe tip
 Create complex arrays at high speeds
 Automated tip coating and ink delivery
 Microfluidic technology – possible ink wells for dipping of probe
tip

16. Sources
 C. A. Mirkin et al, Angew. Chem. Int. Ed. 2004, 43, 30-45.
 Baselt, David. California Institute of Technology. 1993. Images obtained at
http://stm2.nrl.navy.mil/how-afm/how-afm.html
 J. Haaheim et al. Ultramicroscopy 103 (2005) 122
 Gerding, J. D. et al. Journal of American Chemical Soc. 2005 127. 1106-1107.
 R.D. Piner, J. Zhu, F. Xu, S. H. Hong, C. A. Mirkin, Science 1999, 283, 661.
 Oak Ridge National Laboratory. http://homer.hsr.ornl.gov/CBPS/Arraytechnology/