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Lab-on-Chip Workshop March 25, 2016 Eric Johnston Soft Lithography Manager Quattrone Nanofabrication Facility
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What is “Lab-on-a-Chip”?
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We will cover: Designing a mask (I can help with this) Negative resist characteristics Surface preparation Spin coating Exposing through mask Post exposure bake PDMS casting Punch holes PDMS Bonding Filling
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Design a Mask 1.Free software: Layout Editor DraftSight 2.Shapes to be closed polygons. 3.Polymask vendors (10um+): a)outputcity.com b)fineline-imaging.com c)photoplotstore.com 4.Chrome masks with Heidelberg
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Layout Editor
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DraftSight
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Photoresists SU8-2000 series photosensitive epoxy SU8-3000 series KMPR-1000 series QNF supplies SU8-2050, KMPR 1050
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Photoresists
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Making a Master 200C100C
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Photoresist Spin Coating, Baking
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Photoresist Exposure ABM Mask Aligner: Calculate from data sheet Intensity is updated in SOP binder for each interface MA6 Mask Aligner: Simply enter dose required If using 360LP filter, must account for the attenuation
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Photoresist Exposure
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ABM Mask Aligner
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Result: Delamination Exposure Problems: Short Exposure
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Exposure Problems: Film Masks with Thin Features Chrome mask, 5um high features Film mask, 5um high features
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Solution: 360nm long pass filter Exposure Problems: Long Exposure Result: T-Topping
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Exposure Problems: Long Exposure
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Post Exposure Bake (PEB)
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PEB Problems: Thermal Stress Stress cracks due to sudden temperature changes
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PEB Problems: High Aspect Ratio Features Delamination of high features with small footprints (related to thermal stress)
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PDMS Casting degas
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Polymeric Casting: The Miracle of PDMS o Inexpensive 2-Part silicone elastomer o Hydrophobic native state o Surface of PDMS can be rendered hydrophilic with oxygen plasma o Treatment last approximately 30 minutes o Allows bonding to glass or to PDMS o Allows functionalization of PDMS surface with hydrophilic molecules. o Gas permeable o Generally biocompatible, Food grade o Transparent in UV down to 240nm, ideal for fluorescence imaging www.cchem.berkeley.edu brandinside.d eu
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Punch Holes (before bonding!)
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Plasma Treatment for PDMS Bonding PDMS-Glass: 50sccm O 2, 30W, 30s PDMS-PDMS: 50sccm O 2, 30W, 60s
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Tubing
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Filling Priming the device soon after plasma bonding (within 3 hours) yields better results. Fully submerging the device inside a vacuum chamber for 20 minutes yielded the best results.
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Soft Lithography Examples o Microfluidics o Stamping o Force Measurement
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Soft Lithography Examples o Microfluidics o Stamping o Force Measurement
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Soft Lithography Examples Particle Separation
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Soft Lithography Examples Gradient Generator
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Soft Lithography Examples Cell Culture Sugiura et al., Biotechnol. Bioeng. 100, 1156–1165 (2008)
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Soft Lithography Examples o Microfluidics o Stamping o Force Measurement
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Arrayed Stamping Example: Protein Deposition Chen et al (1997) Science, 276:1425 DOI: 10.1126/science.276.5317.1425 Kamat et al (2013) Small, 9:2272 DOI: 10.1002/smll.201202627 Forced Cell Morphology Vesicle Adhesion
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Arrayed Stamping Method Schematic by Steven Henry
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Soft Lithography Examples o Microfluidics o Stamping o Force Measurement
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Force Measurement Example: PDMS cantilevered force transducers Tan et al (2002) PNAS, 100:1484 DOI: 10.1073pnas.0235407100
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Preview of Hands-On Lab Work
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