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| <BR><span style="background:#FF2800">'''THIS PAGE IS UNDER CONSTRUCTION'''</span>
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| ''Unless otherwise stated, all content on this page was created by Claudia Chaves Villarreal, DTU Nanolab''
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| '''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php?title=Specific_Process_Knowledge/Characterization/XPS click here]'''
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| ==PDMS Lab at DTU Nanolab==
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| Polydimethylsiloxane (PDMS), also known as silicone, has become a fundamental material for fabricating microfluidic devices with applications in health, chemistry, biomedical sciences and more.
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| DTU Nanolab has a dedicated laboratory for the processing of PDMS and fabrication of microfluidics located in building 347. The PDMS Lab is part of the PolyFabLab and has been equipped with brand-new instruments funded by the Novo Nordisk Foundation, alongside selected equipment and processes from previous facilities.
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| The laboratory has 4 different areas:
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| 1. Non-cured PDMS: All mixtures of PDMS resin and curing agent are prepared on this area. Cellophan film is provided and must be placed on the table ALWAYS when working with uncured PDMS.
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| 2. Cured PDMS: Only cured PDMS can be handled in this area.
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| 3. Fume hood: safe area for handling volatile chemicals that are hazardous for human and environment health. The spin-coating machine and the hazardous waste are also located in this area.
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| 4. Plasma machine: equipment to condition the surfaces for bonding of parts in microfluidic devices.
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| 5. Storage area: to store chemicals, samples, sample holders, tools, and materials.
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| 6. Personal protective equipment and emergency shower equipment: googles, lab coats, [https://www.inside.dtu.dk/en/work-environment/physical-work-environment/laboratorier-og-vaerksteder/oejenskylleflasker-og-noedbrusere emergency shower and eyewasher] are provided for the safety of lab users
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| ==Material requirements==
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| ==Process flow==
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| ==Mixing PDMS resin and degassing==
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| ==Soft lithography micro molding==
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| '''Mold surface conditioning'''
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| '''Molding by pouring'''
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| '''Molding by spin coating'''
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| '''Baking – Curing'''
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| The PDMS can cure without heating in ~24 hours. Curing the PDMS at higher temperatures in the oven can decrease the time spent curing. The temperatures between 60°C to 100°C can be used, and the choice must be optimized for the specific device design, and the desired mechanical and surface properties. The curing time depends on the temperature and the thickness of PDMS. As a standard procedure to cure PDMS, place the casted PDMS on the mold in the oven for at least 2 hours at ~80°C.
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| [[File:PDMS film casted.jpg|thumb|Photograph of a PDMS microfluidic wafer]]
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| '''Demolding'''
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| After curing, the PDMS microfluidic chip is a solid and chemically inert material. Once cooled, the PDMS is easily peeled off from the mold. The demolding and further processes of cured PDMS must be done in the designated “cured PDMS”. If the demolding does not occur readily, wetting it with isopropanol or ethanol might be helpful. Otherwise, the mold must be conditioned properly before casting the PDMS.
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| ==3D printing==
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| ==Cutting PDMS==
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| '''Punching'''[[File:Manual puncher.jpg|thumb|Example of a 20 mm commercial puncher used to cut individual chips out of a PDMS microfluidic wafer]]
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| '''Laser ablation'''
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| '''Machining/milling'''
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| '''Air/water jet machining'''
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| ==Bonding==
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| '''PDMS/PDMS and PDMS/glass bonding'''
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| '''PDMS/PMMA bonding'''
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| ==References==
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| For further information contact Stephan Sylvest Keller suke@dtu.dk or Claudia Chaves Villarreal cchvi@dtu.dk
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