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This is extremely helpful Eric, thank you.</div>
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Thank you <u>everyone</u> on Labnetwork - I got about a dozen helpful responses, including many SOPs.</div>
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I'll take all this information back and work with the researchers.</div>
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- Russ</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Eric Johnston <ericdj@seas.upenn.edu><br>
<b>Sent:</b> Thursday, September 4, 2025 11:59 AM<br>
<b>To:</b> Russ Renzas <rrenzas@unr.edu><br>
<b>Cc:</b> Lab Network (labnetwork@mtl.mit.edu) <labnetwork@mtl.mit.edu><br>
<b>Subject:</b> Re: [labnetwork] PDMS mold process?</font>
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<p><strong><span style="background-color:#f1c40f">[EXTERNAL EMAIL]</span></strong></p>
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<div dir="ltr">Hi Russ
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<div>We have a separate room in our cleanroom dedicated to PDMS mixing and molding. We have gloves of a very different color in that room which are required to be worn when working with PDMS and are required to be removed before exiting the room. Only the fully
cured devices, cut out and with inlet/outlet ports already punched out, may be removed from the room. That said, most researchers use PDMS in their own (non-cleanroom) labs with very satisfactory results.</div>
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<div>Regarding "gotchas", including tips and tricks, here are a few:</div>
<div>- Be sure to mix the two components VERY well, like for 5ish minutes. If they are not mixed well, the cured PDMS may stick to the master.</div>
<div>- An aluminum tray that can accommodate a wafer is very helpful. We got ours from Kitchendance.com, item #80063, which is big enough for a 4" wafer.</div>
<div>- A 1mm biopsy punch is a great way to add inlet/outlet ports.</div>
<div>- The main cause of failure of the master, next to delamination, is cracking of the wafer.</div>
<div>- It is easier to cut out only the devices needed. Trying to remove the wafer from the PDMS mold can easily crack the wafer.</div>
<div>- "Silanizing" the master can make it easier to remove the mold. We use Trichloro(1H, 1H, 2H, 2H-perfluoro-octyl) silane in a vacuum desiccator. This is really only necessary if there are small features with high aspect ratios.</div>
<div>- A drop of IPA when removing the PDMS mold can be very helpful. It acts as a lubricant.</div>
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<div>Regards</div>
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<div style="font-size:12.8px"><span style="font-size:small">Eric</span></div>
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<div style="font-size:12.8px"><span style="font-size:small">Eric Johnston</span><br>
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<div>Director, Quattrone Nanofabrication Facility</div>
<div>Singh Center for Nanotechnology</div>
University of Pennsylvania
<div>3205 Walnut Street, #109A</div>
<div><a href="mailto:ericdj@seas.upenn.edu" target="_blank">ericdj@seas.upenn.edu</a><br>
<div>T. <a href="tel:215.573.6695" value="+12155736695" target="_blank">215.573.6695</a></div>
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<div>Questions? See the QNF <a href="https://wiki.nano.upenn.edu/wiki/index.php?title=Frequently_Asked_Questions#How_do_I_get_started.3F" originalsrc="https://wiki.nano.upenn.edu/wiki/index.php?title=Frequently_Asked_Questions#How_do_I_get_started.3F" target="_blank">FAQ</a>.</div>
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<div dir="ltr" class="x_gmail_attr">On Thu, Sep 4, 2025 at 8:08 AM Russ Renzas <<a href="mailto:rrenzas@unr.edu">rrenzas@unr.edu</a>> wrote:<br>
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Is anyone familiar with PDMS (or other material) mold fabrication? Any procedures or gotchas to worry about? </div>
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Bio faculty member asking if we can make molds in our fab. I only know how to make semiconductor, photonic, and quantum devices. </div>
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Thanks!</div>
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Russ</div>
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Russ Renzas</div>
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University of Nevada, Reno</div>
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