An Introduction to Dip-Pen Nanolithography

What is DPN? Direct-write patterning technique based on AFM scanning probe technology Direct-write patterning technique based on AFM scanning probe technology AFM tip is coated with “ink” and used to write on surface AFM tip is coated with “ink” and used to write on surface Very reliable bottom-up process (ink deposition rate can be precisely controlled) Very reliable bottom-up process (ink deposition rate can be precisely controlled) Baselt, David. California Institute of Technology Images obtained at

What is DPN? (continued) Compatible with both hard and soft matter on lengthscales below 100 nm 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) 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 Biomolecules can be directly deposited on the surface in ambient temperature, no exposure to etchants, electron beams, or radiation

Advantages of DPN Resolution - 15nm Resolution - 15nm Direct write so only where you want and what you want Direct write so only where you want and what you want Based on AFM - can write and see Based on AFM - can write and see Ambient conditions Ambient conditions Image from J. Haaheim et al. Ultramicroscopy 103 (2005) 122

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

Ink Theory Inks: small organic molecules, organic and biological polymers, colloidal particles, metals ions Inks: small organic molecules, organic and biological polymers, colloidal particles, metals ions C. A. Mirkin et al, Angew. Chem. Int. Ed. 2004, 32.

Ink Theory (continued) Ink-substrate combinations Ink-substrate combinations Tip-substrate molecular transport 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

Ink Theory (continued) Water meniscus from ambient moisture Water meniscus from ambient moisture –Humidity controlled box Modeled after the diagram in R.D. Piner, J. Zhu, F. Xu, S. H. Hong, C. A. Mirkin, Science 1999, 283, 661.

Current Applications DPN is specially advantageous to biomolecular manipulation DPN is specially advantageous to biomolecular manipulation DNA and protein arrays are being fabricated as detection chips 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 DPN resolution is four to five orders of magnitude greater than other lithographic techniques: ultra-high density nanoarrays Image courtesy of Oak Ridge National Laboratory. Obtained at:

Obstacles Most are currently being addressed 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

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

Sources C. A. Mirkin et al, Angew. Chem. Int. Ed. 2004, 43, C. A. Mirkin et al, Angew. Chem. Int. Ed. 2004, 43, Baselt, David. California Institute of Technology Images obtained at Baselt, David. California Institute of Technology Images obtained at J. Haaheim et al. Ultramicroscopy 103 (2005) 122 J. Haaheim et al. Ultramicroscopy 103 (2005) 122 Gerding, J. D. et al. Journal of American Chemical Soc Gerding, J. D. et al. Journal of American Chemical Soc R.D. Piner, J. Zhu, F. Xu, S. H. Hong, C. A. Mirkin, Science 1999, 283, 661. R.D. Piner, J. Zhu, F. Xu, S. H. Hong, C. A. Mirkin, Science 1999, 283, 661. Oak Ridge National Laboratory. Oak Ridge National Laboratory.