Godin:Protocols/Multilayer PDMS

From OpenWetWare

(Difference between revisions)
Jump to: navigation, search
Line 23: Line 23:
*Oven
*Oven
*Aluminum foil
*Aluminum foil
 +
*Scalpel
*Weighing dish
*Weighing dish
*Scale
*Scale
Line 50: Line 51:
*'''Punch valve holes'''
*'''Punch valve holes'''
-
Use the 0.75 mm hole punch to  
+
Cut out each device from the wafer. Be careful to avoid cutting near master features, as it will be reused for future devices.
 +
 
 +
Use the 0.75 mm hole punch to make a hole at the valve inlet for each PDMS device. The stereo-microscope is great for finding your features. Keep the light arms at a low incidence angle with respect to the PDMS surface so the features stand out. Place your PDMS piece on a junk piece of PDMS so you can easily go through without damaging the punch, and keeping holes consistent. The PDMS should be fairly sticky, so do your best to make it smooth. Try to keep holes vertical.
*'''Cleaning'''
*'''Cleaning'''
 +
 +
Rinse devices thoroughly with distilled water, making sure the water goes through the valve hole. Next, sonicate for 5 min in each of these solutions: soapy water, deionised water, ethanol and isopropanol. Dry with nitrogen, store in a closed clean dish.
==Fluidic Layer==
==Fluidic Layer==

Revision as of 15:06, 17 May 2011

Image:Header Logo-1-.jpg

Home        Calendar        Contact        Lab Members        Protocols        Publications        Research        Orders       

Contents

Safety

  • Safety goggles
  • Nitrile gloves
  • Lab coat
  • Clean room gowning
  • Fume hood

Materials

Description

This protocol details the fabrication of a 2 layer PDMS device, consisting of a valve layer (top) and channel layer (below). It is assumed that masters for respective layers have already been fabricated (see Godin:Protocols/SU-8 Master, Godin:Protocols/AZ Master). The idea is to modify the silicone elastomer base to curing agent ratio, thereby modifying PDMS elasticity.

Valve Layer

  • Mix PDMS 7:1

For most devices, 80g of PDMS is sufficient to produce reasonably-sized devices. Weigh 70g of silicone elastomer base on the scale using the weighing dish, then add 10g of curing agent. Make sure to maintain the 7:1 ratio; if too much is added, add more base as required. Use a pipette tip to mix the solution for 10 min under the fume hood. Blow dry the valve master with nitrogen, and place in a polystyrene dish. Use Scotch tape to fix the wafer at the center of the dish by taping all sides. We want to prevent the wafer from floating up, or PDMS from getting under the wafer. Close the dish with the lid.

  • 30 min degass

Place the dish in the vacuum chamber, and allow it to degass for 30 minutes, or until it stops bubbling. To prevent overflow, you may have to periodically break vacuum and allow some bubbles to escape.

  • 12 min @ 80°C

The dish is now placed in the oven for 12 min at 80°C. The idea is to partially cure the PDMS, so it's solid but still sticky. Let the PDMS cool for about an hour afterwards; this will facilitate the next step.

  • Punch valve holes

Cut out each device from the wafer. Be careful to avoid cutting near master features, as it will be reused for future devices.

Use the 0.75 mm hole punch to make a hole at the valve inlet for each PDMS device. The stereo-microscope is great for finding your features. Keep the light arms at a low incidence angle with respect to the PDMS surface so the features stand out. Place your PDMS piece on a junk piece of PDMS so you can easily go through without damaging the punch, and keeping holes consistent. The PDMS should be fairly sticky, so do your best to make it smooth. Try to keep holes vertical.

  • Cleaning

Rinse devices thoroughly with distilled water, making sure the water goes through the valve hole. Next, sonicate for 5 min in each of these solutions: soapy water, deionised water, ethanol and isopropanol. Dry with nitrogen, store in a closed clean dish.

Fluidic Layer

  • Mix PDMS 20:1
  • 30 min degass
  • Spin coat
  • 10 min @ 80°C

Device Fabrication

  • Alignment
  • >2 hrs @ 80°C
  • Punch fluidic holes
  • Cleaning
Personal tools