An Introduction to An Introduction to Dip-Pen Dip-Pen NanolithographyNanolithography

What is DPN?What is DPN?

Direct-write patterning Direct-write patterning technique based on AFM technique based on AFM scanning probe technologyscanning probe technology

AFM tip is coated with AFM tip is coated with “ink” and used to write “ink” and used to write on surfaceon surface

Very reliable bottom-up Very reliable bottom-up process (ink deposition process (ink deposition rate can be precisely rate can be precisely controlled)controlled)

Baselt, David. California Institute of Technology. 1993. Images obtained at <http://stm2.nrl.navy.mil/how-afm/how-afm.html>

What is DPN? What is DPN? (continued)(continued) Compatible with both hard and soft Compatible with both hard and soft matter on lengthscales below 100 nmmatter on lengthscales below 100 nm

Capable of depositing arrays of Capable of depositing arrays of biomolecules on various materials biomolecules on various materials (metals, semiconductors, (metals, semiconductors, functionalized surfaces)functionalized surfaces)

Biomolecules can be directly Biomolecules can be directly deposited on the surface in ambient deposited on the surface in ambient temperature, no exposure to etchants, temperature, no exposure to etchants, electron beams, or radiationelectron beams, or radiation

Advantages of DPNAdvantages of DPN

Resolution - 15nmResolution - 15nm

Direct write so only where you Direct write so only where you want and what you wantwant and what you want

Based on AFM - can write and seeBased on AFM - can write and see Ambient conditionsAmbient conditions

Image from J. Haaheim et al. Ultramicroscopy 103 (2005) 122 Image from J. Haaheim et al. Ultramicroscopy 103 (2005) 122

Advantages continuedAdvantages continued

More than one layerMore than one layer Can work with multiple Can work with multiple “inks” at once“inks” at once

Organic and inorganic inksOrganic and inorganic inks Bottom-up and top-downBottom-up and top-down

Ink TheoryInk Theory

Inks: small organic Inks: small organic molecules, organic and molecules, organic and biological polymers, biological polymers, colloidal particles, metals colloidal particles, metals ionsions

C. A. Mirkin et al, Angew. Chem. Int. Ed. 2004, 32.

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

– Chemical makeup and purity (ink and Chemical makeup and purity (ink and surface)surface)

– Shape of tipShape of tip– Distribution of ink on tipDistribution of ink on tip– TemperatureTemperature– Humidity of surroundingsHumidity of surroundings– Solubility of inkSolubility of ink

Ink Theory Ink Theory (continued)(continued) Water meniscus from ambient Water meniscus from ambient moisturemoisture– Humidity controlled boxHumidity 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 ApplicationsCurrent Applications

DPN is specially advantageous DPN is specially advantageous to biomolecular manipulationto biomolecular manipulation

DNA and protein arrays are DNA and protein arrays are being fabricated as detection being fabricated as detection chipschips

DPN resolution is four to DPN resolution is four to five orders of magnitude five orders of magnitude greater than other greater than other lithographic techniques: lithographic techniques: ultra-high density nanoarraysultra-high density nanoarrays

Image courtesy of Oak Ridge National Laboratory. Obtained at: <http://homer.hsr.ornl.gov/CBPS/Arraytechnology/ZFChipSM.jpg>

ObstaclesObstacles

Most are currently being Most are currently being addressedaddressed– SpeedSpeed– Matching inks to substrates, Matching inks to substrates, correct conditionscorrect conditions

– Smooth surfaces to work onSmooth surfaces to work on– Turning the write head on/off Turning the write head on/off at willat will

Future ApplicationsFuture Applications

Parallel arraysParallel arrays– Passive probe arrayPassive probe array

Duplicate a pattern multiple timesDuplicate a pattern multiple times

– Independent control of each probe Independent control of each probe tiptip Create complex arrays at high speedsCreate complex arrays at high speeds

– Automated tip coating and ink Automated tip coating and ink deliverydelivery Microfluidic technology – possible ink Microfluidic technology – possible ink wells for dipping of probe tipwells for dipping of probe tip

SourcesSources

C. A. Mirkin et al, C. A. Mirkin et al, Angew. Chem. Int. Ed.Angew. Chem. Int. Ed. 20042004, , 4343, 30-45., 30-45. Baselt, David. California Institute of Technology. 1993. Images obtained at Baselt, David. California Institute of Technology. 1993. Images obtained at

http://stm2.nrl.navy.mil/how-afm/how-afm.htmlhttp://stm2.nrl.navy.mil/how-afm/how-afm.html 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. 2005 127. 1106-1107.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.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.

http://homer.hsr.ornl.gov/CBPS/Arraytechnology/http://homer.hsr.ornl.gov/CBPS/Arraytechnology/