Polymers and biopolymers in

micro- and nanotechnology

PolymerscienceNanoscience

Physics Chemistry

Life Sciences Engineering Sciences

Optisch LithographischeStrukturierungstechniken

Softlithographie

Surface DesignMikrodisperseStrukturelemente

Selbstorganisation

BiomimetischesStrukturdesign

Motivation

Polymers and biopolymers in micro- and nanotechnology

What are micro- and nanotechnology about ?

• Majour goals • Representative examples from microtechnology• Representative examples from nanotechnology

What are the materials used in micro- and nanotechnology?

• Silicon, metals, semiconductors and inorganics• Polymers, organic materials

Polymers and biopolymers in micro- and nanotechnology

What are the technologies used in micro- and nanosciences?

• Structuring technologies• Analytical techniques• Self assembly

What is the biological input to micro- and nanotechnology?

• Biomimetic strategies• Biophysical techniques

What are the visionary goals of nanotechnology ?

Goals of nanotechnology

Nanotechnology focuses on

• preparation • analysis • understanding of physical properties and • technological application

of nano- and mesosized objects

Nanoobjects

1-d 2-d 3-d

yy

xy

xz

< 100 nm

Layers Rods Particles

History of nanotechnology

Ultrathin gold layers ( 100 nm)

History of nanotechnology

Technological applications of nanoobjects

Colloidal colours in glases –Optical properties of nanoparticles

History of nanotechnology

Alchemist Kunckel

1682

Johann Kunckel, der am sächsischen Hof diente und sich in der europäischen Glaskunst auskannte, wurde vom Großen Kurfürsten um 1678 nach Brandenburg gerufen. Der wollte nicht nur die Folgen des Dreißigjährigen Krieges mindern, sondern auch günstig zu hochwertigem Glas kommen. Die wichtigsten Rohstoffe wie Holz und Quarzsande waren in der Mark reichlich vorhanden. Unter dem Vorwand des ungestörten Experimentierens wurde Kunckel auf der heutigen Pfaueninsel isoliert. Nicht zuletzt durch seine Arbeit an der Verbesserung des Rubinglases erlangten seine Produkte den Status luxuriöser Exportartikel.

History of nanotechnology

Alchemist Kunckel

1682

Da ihm aber bald auch dort das Gehalt nicht mehr gezahlt wurde, geriet er in wirtschaftliche Schwierigkeiten und er beschwerte sich in Dresden. Die Antwort der kurfürstlichen Minister lautete: “Kann Kunckel Gold machen, so bedarf er kein Geld, kann er solches aber nicht, warum solle man ihm Geld geben?”

History of nanotechnologyDie herrliche rote Farbe der kolloiden Goldlösung hat die Technik schon seit vielen Jahrhunderten im Goldrubinglas benutzt, das, wie Zsigmondy und Siedentopf mit Hilfe des Ultramikroskops bewiesen haben, feste Teilchen metallischen Goldes als färbende Substanz enthält (im Ultramikroskop erscheinen diese Goldteilchen als grünglänzende Scheibchen). Man stellt das echte Rubinglas her, indem man zur Glasmasse Chlorgold zufügt. Bei rascherem Abkühlen erhalt man ein farb-loses Glas; erhitzt man von neuem, bis das Glas erweicht, so läuft es plötzlich prachtvoll rubinrot an. Schlechtes Rubinglas dagegen wird beim Wiedererhitzen blau, violett und rosa; das Ultramikroskop zeigt hier viel hellere und viel weiter voneinander entfernte Teilchen, die im blauen Glase kupferrot, im violetten Glase gelb und dort, wo das Glas rosa ist, grün glänzen.Die Bedeutung der Kolloide für die TechnikK. Arndt in Kolloid Zeitschrift S. 1 (1909)

History of nanotechnology

Justus Liebig: 1843 Preparation of silver mirrors

Michael Farady: 1856 Preparation of ultrathin layers

Observation of red „gold solutions“ as by product

History of nanotechnology

Preparation of nanoobjects

Faraday sols – 1864Nanoparticle preparation

History of nanotechnology

Preparation of nanoobjects

Faraday sols – 1864Nanoparticle preparation

HAu(III)Cl4 Au0reduction

Citrate Ascobic acid ~5 nm

20 nm

History of nanotechnology

Analysis of nanoobjects

Zsigmondy Ultramicroscope – 1900Single particle observation

Scattered light

Nanoparticles

History of nanotechnology

Faraday’s „solutions“ are no real solutions(Tyndal Faraday effect)

History of nanotechnology

Physical properties of nanoobjects

Zsigmondy 1905

History of nanotechnology

Physical properties of nanoobjects

Einstein - Smoluchowski – 1905Diffusion of nanoparticles

History of nanotechnology

Physical properties of nanoobjects

Einstein - Smoluchowki – 1905Diffusion of nanoparticles

Diffusion

Making money with nanotechnology

Au Sol particles (6 nm) : 25 ml , 0.01 % HAuCl4 : 92 €Au 1 Oz : ......

Au 1 Oz : 400 €

Polymers and nanotechnology

Macromolecules are Nanoobjects

Nanoobjects are not necessarily Macromolecules

Macromolecules

Metallic Clusters

Carbon Nanostructures(Fullerenes, Carbon Nanotubes)

Small Organic Molecules

Preparation of Nanostructures

Top

Down Bottom up

Up

Lithography Self assembly

Science Fiction ?Lets build a small world

Complex structures of a small world

/ 10 7 / 10 8

Polymers and nanotechnologyConformation and size of single macromolcules

Freely jointed chain (Frei drehbare Kette):

(Valenzwinkelkette)

(Valenzwinkelkette mit gehinderter Rotation)

Mesophases of amphiphilic molecules

A. Mueller, D. O‘Brien, Chem. Rev. 2002, 102, 727

Colloidal particles and their assemblyColloidosomes

A. D. Dinsmore, et al. Science 298, 1006 (2002)

Micro- and nanostructures through lithographic approaches

L. Jay Guo,*,† Xing Cheng,† and Chia-Fu Chou*,‡

NANO LETTERS 2004 Vol. 4, No. 1 69-73

Polymers and nanotechnology

Polymer coil

Nanoparticle Carbonnanotube

Polymer rod

5 nm – 20 nm 1 nm – 100 nm

Softmatter

Size and shape of objects

Hard material

can change are fixed

Single colloidal objects

Biopolymer Nanoobjects

24.01.11 30

Integration of single molecular motors into man-made microstructures

Montemagno et. al., Science 290 (2000) 155

Polymers and nanotechnologyConformation and size of single macromolcules

End-to-end distance (Fadenendenabstand)

Radius of gyration (Trägheitsabstand)

Persistence length (Persistenzlänge)

Polymers and nanotechnology

Self assembly

can change are fixed

Assemblies of nanoobjects

Ion channels

Functionallity

Polymers in micro- and nanotechnologyWhat are the technologies used in micro- and nanosciences?

• Structuring technologies• Analytical techniques

What is the biological input to micro- and nanotechnology?

• Biomimetic strategies• Biophysical techniques

What are the visionary goals of nanotechnology ?

What can be the positive and negative input on society ?

Micro- and nanostructures through self-assembly

Hui Zhang and Mary J. Wirth* Anal. Chem.2005, 77,1237-1242

Micro- and nanostructures through self-assembly

Micro- and nanostructures through lithographic approaches

L. Jay Guo,*,† Xing Cheng,† and Chia-Fu Chou*,‡

NANO LETTERS 2004 Vol. 4, No. 1 69-73

Micro- and nanostructures through self-assembly

Guillaume Tresset† and Shoji Takeuchi*,‡Anal. Chem.2005, 77,2795-2801

Cell encapsulation in microdroplets

Mingyan He, J. Scott Edgar, Gavin D. M. Jeffries, Robert M. Lorenz, J. Patrick Shelby, andDaniel T. Chiu*Anal. Chem.2005, 77,1539-1544

Micro- and nanotechnology as multidisciplinary fields

Molecular- / Cell- Biology

Chemistry

Engineering sciences

Physics

Micro- and nanotechnology as multidisciplinary fields

Physics

Fundamentals for structuring technologies

Short wavelength radiation from synchrotons

Micro- and nanotechnology as multidisciplinary fields

Physics

Fundamentals for structuring technologies

Optical tweezers Dip pen lithography

Micro- and nanotechnology as multidisciplinary fields

Physics

Understanding physical effects on the meso- and nanoscale

Measuring single molecule mechanical properties

Micro- and nanotechnology as multidisciplinary fields

Physics

Single molecule physics

Moving single molecules

Micro- and nanotechnology as multidisciplinary fields

Physics

Fundamentals for new analytical techniques

SXM (AFM) SXM (SNOM)

Micro- and nanotechnology as multidisciplinary fields

Materials for new structuring technologies

Extreme UV resists for 157 nm irradiation

Chemistry

Micro- and nanotechnology as multidisciplinary fields

Materials for new structuring technologies

Control of mesostructure by polymer design

Chemistry

Micro- and nanotechnology as multidisciplinary fields

Chemical tuning of surfaces

Control of Wettability

Chemistry

Spatial control of Reactivity

Micro- and nanotechnology as multidisciplinary fields

Design of complex structures (for new high tech applications)

Chemistry

Micro- and nanotechnology as multidisciplinary fields

Design of complex structures (for new high tech applications)

Chemistry

Photonic crystals and foams

Colloidal particles and their assemblyColloidosomes

Schematic illustration of the self-assembly process for colloidosomes.

(A) Aqueous solution is added to oil containing colloidal particles. Aqueous droplets are formed by gentle continuous shearing for several seconds.

(B) Particles adsorb onto the surface of the droplet to reduce the total surface energy. These particles are subsequently locked together by addition of polycations, by van der Waals forces, or by sintering the particles.

(C) The structure is transferred to water by centrifugation. The same approach is used to encapsulate oil droplets with a shell of particles from an exterior water phase. Particles adsorbed because of the large oil-water surface energy, which is substantially larger than the difference between the particle-oil and particle-water surface energies; this differs substantially from previous reports, where colloidal particles were adsorbed electrostatically onto oil droplets, which required prior treatment of the droplet’s surface

A. D. Dinsmore, et al. Science 298, 1006 (2002)

Colloidal particles and their assemblyColloidosomes

A. D. Dinsmore, et al. Science 298, 1006 (2002)

Micro- and nanotechnology as multidisciplinary fields

Nature as lecturer – Biomimetic approach

Chemistry

Micro- and nanostructures through self-assembly

Diatomes – self assembled complex structures

Micro- and nanotechnology as multidisciplinary fields

Nature as lecturer – The cell as microsystem with nanofunctional units

Molecular- / Cell- Biology

Micro- and nanotechnology as multidisciplinary fields

Nature as lecturer – Molecular motors in biology (translation & rotation)

Molecular- / Cell- Biology

Micro- and nanotechnology as multidisciplinary fields

Man-machine interfacingIntegrating biological function into microsystems

Engineering sciences

Neuron attached to a microchip(MPI Martinsried- Munich)

Micro- and nanotechnology as multidisciplinary fields

Creating new microproduction technology

Engineering sciences

Micro- and nanotechnology as multidisciplinary fields

Creating new microdevice technology

Engineering sciences

Microfluidics

Monolitic fabrication:

Integration of differentfunctional units Without assembly process

2‘ nd lecture 09.11.2009

Lithographical MethodsPhysical Principles

TechnologiesMaterials

Polymers in micro- and nanotechnology

3d structures2d structuresLateral structures

DNA Chip Microfluidic channel

3d structures2d structuresLateral structures

D

D: lateral resolution D: lateral resolutionH: height

Aspect ratio α

α = H/D

D

D

Top down technologies for micro-/nanostructure preparation

1 µm10 µm100 µm 100 nm 10 nm 1 nm

Sub-micrometer

Optical Lithography

Ebeam Lithography

Softlithography

AFM based Lithography

Top down technologies for micro-/nanostructure preparation

2d,3d Electronbeam & Optical, X-ray Lithography,

2d,3d Soft-Lithography

2d AFM based Lithography (dip pen, SNOM,..)

Ebeam and optical lithography

Substrate

Resist layer

Resist layerPositive resist

(becomes soluble upon irradiation)Negative resist

(becomes insoluble upon irradiation)

Pattern transfer

Irradiation

Film formation by spin coating

Substrate

Resist layer

Inhomogeneous thickness of resist layer and time evolution of layer thickness

Film formation by spin coating

Process and materials parameter influencing film thickness

• Solution viscosity • Solid content • Angular speed • Spin Time

Wetting of (polymer) solutions on solid substrates

ω ~ 0 deg. Spreading

0 < ω < 90 deg. Wetting

ω > 90 deg. Non-wetting

Wetting and dewetting of thin polymer (liquid films) on solidsubstrates

Stability of thin films on surfaces

1) Stable film , 2) Unstable film 3) Metastable filmΦ effective interface potential

R. Seemann, S. Herminghaus, and K. Jacobs, PRL 86 (2001) 5534

Stability of thin films on surfaces

R. Seemann, S. Herminghaus, and K. Jacobs, PRL 86 (2001) 5534

Stability of thin films on surfaces

R. Seemann, S. Herminghaus, and K. Jacobs, PRL 86 (2001) 5534

SiSiOPolymerfilm

dh

h: thickness of polymer filmd: Thickness of SiO layer

Stability of thin films on surfaces on variable SiO interface

R. Seemann, S. Herminghaus, and K. Jacobs, PRL 86 (2001) 5534

Wetting and partial wetting on surfaces

G. Reiter et. Al. Langmuir 15 (1999) 2551

25.10.2010

Optical lithography

Thick layer resist technology : High aspect ratios

Optical lithography

Thick layer resist technology : High aspect ratios

H

I(d)

I(d) = I * exp- ε * d

Inhomogeneous irradiation of polymer due to strong optical absorption (H > 100 µm)

Optical lithography

Thick layer resist technology : Thick layer resist systems (SU-8)

Optical lithography

T-BOC cleavage

Acid catalyst negative resist

Alkaline development

Chemically amplified negative resist

Optical lithography

T-BOC cleavage

Acid catalyst negative resist

Alkaline development

Chemically amplified negative resist

3‘ rd lecture 25.10.2010

Optical lithography

Light sources and structure resolution

Hg KrF ArF F2

365nm

248nm

193nm

157nm

Optical lithography

Lenses for KrF laser sources (248 nm)

Structure resolution <180 nm

Lense Material Calziumfluorid

Optical Transmission highabove 170 nm

No birefringence

Optical lithography

Lenses for ArF laser sources (198 nm)

Structure resolution 80 nm

Increasing na to ~ 1.3

Optical lithography

Resist for 157 nm VUV Lithography

Optical lithography

Resist for 157 nm VUV Lithography

Optical lithography

Two-photon lithography for complex 3d structures

Optical lithography

Two-photon lithography for complex 3d structures

Optical lithography

Two-photon lithography for complex 3d structures

Optical lithographyTwo-photon lithography for complex 3d structures

Optical lithographyQuantum dots as 2 photon initiators

CdS

o

o

o o

( )

2 hν

N.C. Strandwitz JACS 2008, 130(26), 8280-8288

Optical lithographyin aqueous solutions

Jhaveri, et. al. Chem. Mater. 2009, 21 (10), 2004 ff.

Optical lithography2 Photon photoabsorption

Optical lithography of complex 3d microstructures Multiphoton fabrication of chemically responsive protein hydrogels for microactuationBryan Kaehr and Jason B. Shear , PNAS 105 (2008) , 8850 ff.

Dynamic cell enclosures

Optical lithography of complex 3d microstructures Multiphoton fabrication of chemically responsive protein hydrogelsBryan Kaehr et. al. , PNAS 101 (2004) , 16104 ff.

Guiding neurons by crosslinked BSA

Optical lithographyin aqueous solutions

Jhaveri, et. al. Chem. Mater. 2009, 21 (10), 2004 ff.

Maskless optical lithography - A simple setup

Musgraves et. al. Am. J. Phys. 2005, 73 (10), 980 ff.

100 µm lines 500 µm pitch

Maskless optical lithography – 3d stereolithography

Sun et. al. Sensors and Actuators A 121, 2005, 113 ff.

Maskless optical lithography – 3d stereolithography

Choi et. al. J. Mat. Process. Tech. 209, 2009, 5494 ff.

Maskless optical lithography – 3d stereolithography

Choi et. al. J. Mat. Process. Tech. 209, 2009, 5494 ff.

Kidney scaffold

DMD chip element

Monk et. al. Microelectronic Eng., 27, 1995, 489 ff.

Optical lithography in microfluidic systems

Lee et. al. Lab Chip 9, 2009, 1670 ff.

Optical lithography in microfluidic systems

Chung et. al. Nature Materials 7, 2008, 581 ff.

Optical lithography in µ-fluidic systems – Particle assembly

Chung et. al. Nature Materials 7, 2008, 581 ff.

Multi-LED array

Grossmann et. al. J. Neural Eng., 11, 2010, 016004 ff.

Multi-LED array

Grossmann et. al. J. Neural Eng., 11, 2010, 016004 ff.

Local stimulation of nerve cells

Ebeam lithography Penetration depth of electrons with different energies in different materials

Ebeam lithography Penetration depth of electrons with different energies

Ebeam lithography Resolution down to 8 nm (A. Tilke LMU München) – Resist: Calixarene

Ebeam lithography Chemical structure of Calixarene

Ebeam lithography SCALPEL Technique

Ebeam lithography SCALPEL Technique

Synchroton lithography / SynchrotonX-rays

Synchroton lithography X-rays

Synchroton lithography / LIGA X-rays

Synchroton lithography / Mask productionX-rays

Polymer embossing

Embossing machine(Jenoptik)

Process stepsCycle time ~ 7 minutes

Heating of substrate and tools above Tg

Application of pressure (~ kN)

Cooling of substrate and embossingtool below Tg

Removal of tool

Polymer embossing

Silicon master embossing tool Polymer replica made by embossing

Polymer microysystems

Lensarrays Beam splitter

Microdropdeposition

Polydimethylsiloxane (PDMS) - The material

Linear flexible polymer (liquid @RT)

Pt

Curing

CrosslinkingFlexible crosslinkedRubber ( @RT)

- Me : - CH3

Polydimethylsiloxane (PDMS) - The material

Chemical crosslinking by hydrosilylation

Schmid,H. Macromolecules 33, 3042 (2000)

Polydimethylsiloxane (PDMS) - The material

Chemical modification by hydrosilylation

(-O-CH2-CH2)- EO

Hydrophilic

Polydimethylsiloxane (PDMS) - The material

Jessamine Ng Lee, Cheolmin Park,† and George M. Whitesides*

Anal. Chem.2003, 75,6544-6554

Polydimethylsiloxane (PDMS) - The materialT.R.E. Simpsona, Z. Tabatabaianb, C. Jeynesb, B. Parbhooc, and J.L. Keddiea*

Polydimethylsiloxane (PDMS) - The materialHydrophilization by surface plasma treatment

O. Steinbock, Langmuir 19, 8117 (2003)

Liquid filling of a capillary by Surface interactions

S. Stark,Microelectronic Eng. 67/68, 229 (2003)

S. Stark,Microelectronic Eng. 67/68, 229 (2003)

Liquid filling of a capillary by Surface interactions

Polydimethylsiloxane (PDMS) - The materialHydrophilization by surface plasma treatment

O. Steinbock, Langmuir 19, 8117 (2003)

Polydimethylsiloxane (PDMS) - The materialHydrophilization by surface plasma treatment

M. Meincken, T.A. Berhane, P.E. Mallon, Polymer 46 (2005) 203–208

Hydrophobic recovery measured by surcface force AFM

Polydimethylsiloxane (PDMS) - The material

Compression mold 2 N/mm2

Compression mold 9.7 N/mm2

Schmid,H. Macromolecules 33, 3042 (2000)

Permeation induced flow in PDMS channels

P. Silberzan, Europhys. Letters 68, 412 (2004)

Permeation induced flow in PDMS channels

P. Silberzan, Europhys. Letters 68, 412 (2004)

Permeation induced flow in PDMS channels

P. Silberzan, Europhys. Letters 68, 412 (2004)

TIRF measurement of particle velocity near surfaces

K.Breuer2003 ASME International Mechanical Engineering Congress & ExpositionWashington, D.C., November 16-21, 2003

TIRF measurement of particle velocity near surfaces

K.Breuer2003 ASME International Mechanical Engineering Congress & ExpositionWashington, D.C., November 16-21, 2003

Unconventional lithographic techniques

Unconventional lithographic techniques

Softlithographic techniques

Se-Jin Choi,† Pil J. Yoo,‡ Seung J. Baek,† Tae W. Kim,† and Hong H. Lee*,‡J. AM. CHEM. SOC. 2004, 126, 7744-7745

Softlithographic techniques

Se-Jin Choi,† Pil J. Yoo,‡ Seung J. Baek,† Tae W. Kim,† and Hong H. Lee*,‡J. AM. CHEM. SOC. 2004, 126, 7744-7745

UV induced radical polymerisation of polyurethaneacrylates

Softlithographic techniques

Se-Jin Choi,† Pil J. Yoo,‡ Seung J. Baek,† Tae W. Kim,† and Hong H. Lee*,‡J. AM. CHEM. SOC. 2004, 126, 7744-7745

Softlithographic techniques

Se-Jin Choi,† Pil J. Yoo,‡ Seung J. Baek,† Tae W. Kim,† and Hong H. Lee*,‡J. AM. CHEM. SOC. 2004, 126, 7744-7745

Rigiflex lithography

Se-Jin Choi,† Pil J. Yoo,‡ Seung J. Baek,† Tae W. Kim,† and Hong H. Lee*,‡J. AM. CHEM. SOC. 2004, 126, 7744-7745

Rigiflex lithography

Se-Jin Choi,† Pil J. Yoo,‡ Seung J. Baek,† Tae W. Kim,† and Hong H. Lee*,‡J. AM. CHEM. SOC. 2004, 126, 7744-7745

Softlithographic techniques

Zentel , Advanced Materials 14, 588 (2002)

Softlithographic techniques Polymerisable conducting polymer

Zentel , Advanced Materials 14, 588 (2002)

PDMS based complex microfluidic systems

S. Quake,Science 298, 580 (2002)

Multilayer µ-fluidic systems

a) Fluidic transport layer

b) Control layer

Complex shaped 3d nanoparticles

S.E.A. Gratton et al. / Journal of Controlled Release 121 (2007) 10–18

Larken E. Euliss, Julie A. DuPont, Stephanie Gratton and Joseph DeSimoneChem. Soc. Rev., 2006, 35, 1095–1104

Complex shaped 3d nanoparticles

Larken E. Euliss, Julie A. DuPont, Stephanie Gratton and Joseph DeSimoneChem. Soc. Rev., 2006, 35, 1095–1104

S.E.A. Gratton et al. / Journal of Controlled Release 121 (2007) 10–18

Complex shaped 3d nanoparticles

Complex shaped 3d nanoparticles

Jason P. Rolland,† Benjamin W. Maynor,† Larken E. Euliss,† Ansley E. Exner,†Ginger M. Denison,† and Joseph M. DeSimoneJ. AM. CHEM. SOC. 9 VOL. 127, NO. 28, 2005 10099

Complex shaped 3d nanoparticles

Larken E. Euliss, Julie A. DuPont, Stephanie Gratton and Joseph DeSimoneChem. Soc. Rev., 2006, 35, 1095–1104

Polymers in micro- and nanotechnology

3d structures2d structuresLateral structures

DNA Chip Microfluidic channel

„Surface Engineering“

Tailored Surface Chemistry

SiO2 X3Si-O-R

Al2O3 (OH)3-P-O-R

Au, Cu, Ag HS-R

„Surface Engineering“

Surface Polymerized Polypeptides

Poly-γ-benzylglutamate

Orientational Change of α-Helix by solventResulting change in layer thickness

Poly-γ-benzylglutamate

Orientational Change of α-Helix by solventResulting change in layer thickness

„Surface Engineering“

Surface Patterning

Surface patterning

Microcontact Printing(Whitesides)

Electron Beam Lithography of Self-Assembled Monolayers(Craighead)

Dip-Pen Lithography of Self-Assembled Monolayers(C.A. Mirkin)

1 µm

1 nm

Micro-contact printing

Siliconmicrostructure

or PMMA resist

Polymer stamp

(PDMS)

Micro-contact printing

Polymer stamp

(PDMS)

„Ink“

Micro-contact printing

Polymer stamp

(PDMS)

„Ink“

Micro-contact printing of solutions

M. Wang, H.-G. Braun, T. Kratzmüller, E. Meyer, Adv. Mater. 13, 1312 (2000)

Micro-contact printing of solutions

M. Wang, H.-G. Braun, T. Kratzmüller, E. Meyer, Adv. Mater. 13, 1312 (2000)

Micro-contact printing of dispersions

M.M. Sung,Lee B. Chem. Mater. 2007

Micro-contact printing of dispersions

M.M. Sung,Lee B. Chem. Mater. 2007

Colloidal particles on the mask

Micro-contact printing of dispersions

M.M. Sung,Lee B. Chem. Mater. 2007

Colloidal particles transfered to a surface by micro-contact printing(The particles are chemically attached to the surface)