Presentation: Microfabrication of Polymeres Ferdinand METZLER HKUST / 26 November 2014

1 Agenda Introduction Manufacturing Processes Applications Plastics and Polymers

2 Introduction Why plastics? / Substrates used in Microtechnology Why? 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 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

3 Agenda Introduction Manufacturing Processes Applications Plastics and Polymers

4 Plastics and Polymers Polymer Categories Why? Categories  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? Structures

5 Agenda Introduction Manufacturing Processes Applications Plastics and Polymers

6 Manufacturing Process Polymerization Why? Polymerization 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

7 Manufacturing Process Lithography SU-8 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

8 Manufacturing Process Replication (1) Why? Replication Technology  Embossing  Polymer substrate placed in system and heated up over T g  Template structure heated up to T g 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

9 Manufacturing Process Replication (2) Why? Replication Technology  Thermoforming  Heat polymer over T g (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

10 Manufacturing Process Stereolithography Why? Stereolithography 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

11 Agenda Introduction Manufacturing Processes Applications Plastics and Polymers

12 Applications Plastic Applications Why? Plastic Applications  Stretchable microsystems  Micro fluid units and flow cells  Microanalysis units  Clinical chemistry and diagnostics  Micro reactors and containers  Cantilevers  Polymer MEMS

13 References [1] Satoru Shoji* and Kyoko Masui Department of Applied Physics, Osaka University, Osaka, Japan Nano-/Microfabrication, Encyclopedia of Polymeric Nanomaterials DOI / _108-2 [2]H. Becker, C. Ga ̈ rtner, Polymer microfabrication technologies for microfluidic systems, Anal. Bioanal. Chem. 2008, 390, [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 ̈ tting, W. Ro ̈ pke, H. Becker, C. Ga ̈ rtner, Polymer microfabrication Technology Microsystem Technologies 8 (2002) 32–36 Ó Springer-Verlag 2002 [7] 25 th November 2014http:// [8]J. Brandrup, E. H. Immergut, E. A. Grulke, Eric A. Grulke, D. Bloch, Polymer Handbook, 4th edition, 1999, Wiley Interscience [9] 25 th November 2014http://