Presentation: Microfabrication of PolymeresFerdinand METZLER

HKUST / 26 November 2014

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Agenda

Introduction

Manufacturing Processes

Applications

Plastics and Polymers

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IntroductionWhy plastics? / Substrates used in Microtechnology

Why? Why Plastics?Why Plastics?

Huge diversity of plastic materials

Wide variety of properties like chemical resistance, inertness, deformability etc.

Multitude of methods for device fabrication and processing

Cheap and disposable (contamination, medical applications)

Many standard laboratory items are already plastics (pipettes, tubes, beads etc.)

Respective chemistry and protocols exist

Why?Substrate mostly used in MicrotechnologySubstrate mostly used in Microtechnology

Silicon+ Wide range of fabrication methods (etch

stops, etching techniques, etc.) - Electrically and thermally conductive,

brittle

Glass+ Chemically inert, transparent- Etching, trough holes, expensive

Plastics+ Wide range of tailored polymers

formulations available+ Low cost fabrication, rapid prototyping+ Biocompatible, optically transparent- Not as inert as glass or quartz, lower

temperature resistance- Some are sensitive to moisture

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Agenda

Introduction

Manufacturing Processes

Applications

Plastics and Polymers

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Plastics and PolymersPolymer Categories

Why? CategoriesCategories

Thermoplasts Can be thermally deformed Amorphous or partially crystalline Physical interactions (no chemical

bonds between chains) PC, PE, PP, etc.

Duroplasts Hard and glasslike polymers Not deformable after initial setting,

brittle Strongly three-dimensional cross-linked

polymers

Elastomers Elastic polymer Weakly cross linked At ambient temperature relatively soft

Why? StructuresStructures

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Agenda

Introduction

Manufacturing Processes

Applications

Plastics and Polymers

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Manufacturing ProcessPolymerization

Why? Polymerization ProzessPolymerization Prozess

Polyaddition Monomers bond together via

rearrangement of bonds No loss of any atom of molecule

Polycondensation Monomers bond together By-product such as water or methanol

Radical Polymerization Successive addition of free radical

building blocks Process starts with an Initiation then

Propagation and Recombination

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Manufacturing ProcessLithography SU-8

SU-8 Processing SU-8 Processing

Substrate silicon wafer

Sacrificial layer, e.g., Cr-Au-Cr

SU-8 deposition (spin-coating)

Pre-bake at 90°C

UV-exposure

Post-bake at 90°C

Repeat deposition through post-bake steps to achieve 3D microstructures

Development in solvent to remove unexposed SU-8

Structure release by sacrificial layer etching

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Manufacturing ProcessReplication (1)

Why? Replication TechnologyReplication Technology

Embossing Polymer substrate placed in system and

heated up over Tg Template structure heated up to Tg or

slightly higher Template structure pressed into polymer Template and substrate cooled down

such that the substrate can be separated

Injection Molding Molten polymer is forced under high

pressure into a mild cavity Pellets conveyed forward by feeding

screw, heated up such that there is molten polymer before the nozzle

Polymer held in mold until solidification, then mold opens and the part is removed

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Manufacturing ProcessReplication (2)

Why? Replication TechnologyReplication Technology

Thermoforming

Heat polymer over Tg (glass-liquid- transition temperature)

Force hot material against counter of a mold

Mechanical, air or vacuum pressure Simple and fast

Casting

Casting mostly on a silicon substrate Resolution of the method: approx. 50nm

to 1µm Basic lab setup is compact and

straightforward

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Manufacturing ProcessStereolithography

Why? Stereolithography processStereolithography process

Vat filled with photo curable liquid resin

Laser operation and UV-induced solidification

High-intensity laser beams

Solidification only at focus point

Platform is lowered by certain distance

Next layer of the object is shaped until completion

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Agenda

Introduction

Manufacturing Processes

Applications

Plastics and Polymers

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ApplicationsPlastic Applications

Why?Plastic ApplicationsPlastic Applications

Stretchable microsystems

Micro fluid units and flow cells

Microanalysis units

Clinical chemistry and diagnostics

Micro reactors and containers

Cantilevers

Polymer MEMS

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References

[1] Satoru Shoji* and Kyoko Masui Department of Applied Physics, Osaka University, Osaka, Japan Nano-/Microfabrication, Encyclopedia of Polymeric Nanomaterials DOI 10.1007/978-3-642-36199-9_108-2

[2] H. Becker, C. Gartner, Polymer microfabrication technologies for microfluidic systems, Anal. Bioanal. Chem. 2008, 390, 89-111.

[3] A. Manz, H. Becker (eds.), Microsystem technology in the life sciences, Springer, Berlin, 1998

[4] M. Madou, Fundamentals of Microfabrication and Nanotechnology, CRC Press, New York, 2012; 3rd edition

[5] J. J. Brandner, 2011, published in Rossiiskii Khimicheskii Zhurnal, 2011, Vol. 55, No. 2, pp. 9–15

[6] O. Ro Ntting, W. Ro Npke, H. Becker, C. Ga Nrtner, Polymer microfabrication Technology Microsystem Technologies 8 (2002) 32–36 O Springer-Verlag 2002

[7] http://www.cmst.be/groups/stretchablemicrosystems.html, 25th November 2014

[8] J. Brandrup, E. H. Immergut, E. A. Grulke, Eric A. Grulke, D. Bloch, Polymer Handbook, 4th edition, 1999, Wiley Interscience

[9] http://www.chemiereport.at/mikrochip-ersetzt-chemielabor, 25th November 2014