Difference between revisions of "PDMS"

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{{#ifeq: {{PDMS}} | Template | | [[Category:Chemicals]]}}
 
{{#ifeq: {{PDMS}} | Template | | [[Category:Chemicals]]}}
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==Overview==
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[[File:PDMS1.jpg|300px|right|frameless| PDMS molecule]]
 
Polydimethylsiloxane ([[PDMS]])  belongs to a group of polymeric organo-silicon compounds that are commonly referred to as silicones. PDMS is non-toxic, optically clear, bio compatible, flexible and chemically stable. The PDMS chemical structure can be represented as:
 
Polydimethylsiloxane ([[PDMS]])  belongs to a group of polymeric organo-silicon compounds that are commonly referred to as silicones. PDMS is non-toxic, optically clear, bio compatible, flexible and chemically stable. The PDMS chemical structure can be represented as:
  
<gallery>
 
PDMS1.jpg|PDMS molecule
 
</gallery>
 
  
 
PDMS can be synthesized with a variety of end groups suitable for a wide variety of applications. The PDMS used in soft lithography, in particular, is methyl group terminated. In addition the base polymer is available in different molecular weights and viscosities.
 
PDMS can be synthesized with a variety of end groups suitable for a wide variety of applications. The PDMS used in soft lithography, in particular, is methyl group terminated. In addition the base polymer is available in different molecular weights and viscosities.
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==Processing Equipment==
 
==Processing Equipment==
 
PDMS is Processed in [[Solvent Bench 94]]. See [[Solvent Bench 94/Processes]]
 
PDMS is Processed in [[Solvent Bench 94]]. See [[Solvent Bench 94/Processes]]
===Etching PDMS===
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===Etching===
At LNF PDMS can be dried etched in the Plasmatherm 790 using and oxygen only based recipe
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{{Note|Please make a helpdesk ticket for assistance setting up a PDMS RIE process.|reminder}}
[[http://lnf-wiki.eecs.umich.edu/wiki/Plasmatherm_790/Processes/m_pary1| Plasmatherm 790]]
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Typically PDMS is etched with a mixture of O<sub>2</sub> and a fluorine-containing gas such as SF<sub>6</sub> or CF<sub>4</sub>.
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* [[Plasmatherm 790]]
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* [[LAM 9400]]
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* [[STS Glass Etcher]]
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===Surface Treatments===
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* SiO<sub>2</sub> Conversion - The surface of PDMS can be converted into an SiO<sub>2</sub> like material by selectively etching the hydrocarbon with ozone.
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** [[Deep UV SenLights PL16]]
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**[https://www.sciencedirect.com/science/article/abs/pii/S0925400503007482 Reference]
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* PDMS-PDMS and PDMS-glass adhesion
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This treatment, commonly used in the asembly of microfluidics, is done to modify the surface of the PDMS to facilitate adhesion. This is done in the [[Glen 1000P Plasma Cleaner]] which is part of the microfluidic fabrication suite.
  
 
==Process Notes==
 
==Process Notes==
PDMS is usually patterned by molding or soft lithography. Its chemical innertness, makes it difficult to wet etch and dry etch. Usually the dry etch of PDMS yields rough surfaces and in most of the cases residue. Several pares have been written about a combination of dry and wet etching <ref>https://iopscience.iop.org/article/10.1088/0960-1317/19/4/047002/meta</ref>
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*PDMS is usually patterned by molding or soft lithography. Its chemical innertness, makes it difficult to wet etch and dry etch. Usually the dry etch of PDMS yields rough surfaces and in most of the cases residue. Several pares have been written about a combination of dry and wet etching <ref>https://iopscience.iop.org/article/10.1088/0960-1317/19/4/047002/meta</ref>
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*PDMS is permeable to gases and solvents, this is why it used as a permeable membrane in some microfluidic applications, but when un vacuum it looses volume and expands when brough back into air. This is a problem when it is needed as a substrate for metal deposition. PDMS swells when immersed in a solvent such as acetone, this volume change should be kept in mind when patterning PDMS with photoresist.
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*In general PDMS is low surface energy material, plasma surface modification can selectively change the surface energy  <ref>Applied Surface Science 258 (2012) 9427– 9431</ref>
  
==Technical Data Sheet==
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*Uncured PDMS is often used as an adhesion layer between PDMS layers
  
[[https://www.dow.com/content/dam/dcc/documents/en-us/productdatasheet/11/11-31/11-3184-sylgard-184-elastomer.pdf?iframe=true| Sylgard 184 Data Sheet]]
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==Processes==
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===PDMS in Soft Lithography ===
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For acomplete description of Soft Lithography in LNF and particular instructions how to mix and work with PDMS go to
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*[[Soft lithography]]
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* [[https://docs.google.com/document/d/1nLQS2AXEWX3MISWfj191QWd_zvJPhPvusSqXRn192KQ/preview PDMS SOP]]
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==Technical Data ==
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[https://www.dow.com/content/dam/dcc/documents/en-us/productdatasheet/11/11-31/11-3184-sylgard-184-elastomer.pdf?iframe=true| Sylgard 184 Data Sheet]<br>
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[http://web.mit.edu/sriram/Public/Graphics/PDMSCharacterization-BiomedAppn.pdf PDMS Characterization for Biomedical applications]<br>
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Characterization of Polydimethylsiloxane (PDMS) Properties for Biomedical Micro/Nanosystems <ref>Mata, A., Fleischman, A.J. & Roy, S. Characterization of Polydimethylsiloxane (PDMS) Properties for Biomedical Micro/Nanosystems. Biomed Microdevices 7, 281–293 (2005). https://doi.org/10.1007/s10544-005-6070-2</ref>
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The fingerprint region of the FTIR spectrum of PDMS is shown below <ref>https://doi.org/10.1016/j.apsusc.2011.12.117</ref>:
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[[File:PDMS fingerprint.png|300px|PDMS FTIR fingerprint region]]
  
 
==References==
 
==References==
  
 
[https://pubs.acs.org/doi/pdf/10.1021/acsami.7b18394 Beyond Sylgard 184- Silicones for Stretchable Applications ]<br>
 
[https://pubs.acs.org/doi/pdf/10.1021/acsami.7b18394 Beyond Sylgard 184- Silicones for Stretchable Applications ]<br>
 
 
 
[https://www.youtube.com/watch?v=zWQTnH79l_8 How to mix PDMS]
 
[https://www.youtube.com/watch?v=zWQTnH79l_8 How to mix PDMS]

Latest revision as of 10:28, 21 April 2020

Warning Warning: This page is has not been released......
PDMS molecule

Polydimethylsiloxane (PDMS) belongs to a group of polymeric organo-silicon compounds that are commonly referred to as silicones. PDMS is non-toxic, optically clear, bio compatible, flexible and chemically stable. The PDMS chemical structure can be represented as:


PDMS can be synthesized with a variety of end groups suitable for a wide variety of applications. The PDMS used in soft lithography, in particular, is methyl group terminated. In addition the base polymer is available in different molecular weights and viscosities. LNF stocks Sylgard 184 (from Dupont Corp.) which has a viscosity in the 4000 - 6500 cSt.

Processing Equipment

PDMS is Processed in Solvent Bench 94. See Solvent Bench 94/Processes

Etching

Please make a helpdesk ticket for assistance setting up a PDMS RIE process.

Typically PDMS is etched with a mixture of O2 and a fluorine-containing gas such as SF6 or CF4.

Surface Treatments

  • SiO2 Conversion - The surface of PDMS can be converted into an SiO2 like material by selectively etching the hydrocarbon with ozone.
  • PDMS-PDMS and PDMS-glass adhesion

This treatment, commonly used in the asembly of microfluidics, is done to modify the surface of the PDMS to facilitate adhesion. This is done in the Glen 1000P Plasma Cleaner which is part of the microfluidic fabrication suite.

Process Notes

  • PDMS is usually patterned by molding or soft lithography. Its chemical innertness, makes it difficult to wet etch and dry etch. Usually the dry etch of PDMS yields rough surfaces and in most of the cases residue. Several pares have been written about a combination of dry and wet etching [1]
  • PDMS is permeable to gases and solvents, this is why it used as a permeable membrane in some microfluidic applications, but when un vacuum it looses volume and expands when brough back into air. This is a problem when it is needed as a substrate for metal deposition. PDMS swells when immersed in a solvent such as acetone, this volume change should be kept in mind when patterning PDMS with photoresist.
  • In general PDMS is low surface energy material, plasma surface modification can selectively change the surface energy [2]
  • Uncured PDMS is often used as an adhesion layer between PDMS layers

Processes

PDMS in Soft Lithography

For acomplete description of Soft Lithography in LNF and particular instructions how to mix and work with PDMS go to

Technical Data

Sylgard 184 Data Sheet
PDMS Characterization for Biomedical applications
Characterization of Polydimethylsiloxane (PDMS) Properties for Biomedical Micro/Nanosystems [3]

The fingerprint region of the FTIR spectrum of PDMS is shown below [4]:

PDMS FTIR fingerprint region

References

Beyond Sylgard 184- Silicones for Stretchable Applications

How to mix PDMS

  1. https://iopscience.iop.org/article/10.1088/0960-1317/19/4/047002/meta
  2. Applied Surface Science 258 (2012) 9427– 9431
  3. Mata, A., Fleischman, A.J. & Roy, S. Characterization of Polydimethylsiloxane (PDMS) Properties for Biomedical Micro/Nanosystems. Biomed Microdevices 7, 281–293 (2005). https://doi.org/10.1007/s10544-005-6070-2
  4. https://doi.org/10.1016/j.apsusc.2011.12.117