Lab-on-Chip Workshop March 25, 2016 Eric Johnston Soft Lithography Manager Quattrone Nanofabrication Facility

What is “Lab-on-a-Chip”?

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

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

Layout Editor

DraftSight

Photoresists  SU series photosensitive epoxy  SU series  KMPR-1000 series  QNF supplies SU8-2050, KMPR 1050

Photoresists

Making a Master 200C100C

Photoresist Spin Coating, Baking

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

Photoresist Exposure

ABM Mask Aligner

Result: Delamination Exposure Problems: Short Exposure

Exposure Problems: Film Masks with Thin Features Chrome mask, 5um high features Film mask, 5um high features

Solution: 360nm long pass filter Exposure Problems: Long Exposure Result: T-Topping

Exposure Problems: Long Exposure

Post Exposure Bake (PEB)

PEB Problems: Thermal Stress Stress cracks due to sudden temperature changes

PEB Problems: High Aspect Ratio Features Delamination of high features with small footprints (related to thermal stress)

PDMS Casting degas

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 brandinside.d eu

Punch Holes (before bonding!)

Plasma Treatment for PDMS Bonding PDMS-Glass: 50sccm O 2, 30W, 30s PDMS-PDMS: 50sccm O 2, 30W, 60s

Tubing

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.

Soft Lithography Examples o Microfluidics o Stamping o Force Measurement

Soft Lithography Examples o Microfluidics o Stamping o Force Measurement

Soft Lithography Examples Particle Separation

Soft Lithography Examples Gradient Generator

Soft Lithography Examples Cell Culture Sugiura et al., Biotechnol. Bioeng. 100, 1156–1165 (2008)

Soft Lithography Examples o Microfluidics o Stamping o Force Measurement

Arrayed Stamping Example: Protein Deposition Chen et al (1997) Science, 276:1425 DOI: /science Kamat et al (2013) Small, 9:2272 DOI: /smll Forced Cell Morphology Vesicle Adhesion

Arrayed Stamping Method Schematic by Steven Henry

Soft Lithography Examples o Microfluidics o Stamping o Force Measurement

Force Measurement Example: PDMS cantilevered force transducers Tan et al (2002) PNAS, 100:1484 DOI: pnas

Preview of Hands-On Lab Work