SmartCHANNEL®
PDMS microchannel fabrication protocol
Step-by-step video guide
Learn how to fabricate PDMS microchannels for cell migration assays using the 4Dcell SmartChannel® Microchannel Fabrication Kit.
This step-by-step protocol covers PDMS molding and curing, microchannel chip bonding to glass-bottom dishes, surface coating and cell seeding.
The SmartChannel® kit enables researchers to fabricate microfluidic devices with defined channel geometries for studying cell migration, mechanical confinement and cell behavior under controlled physical conditions.
MATERIALS & EQUIPMENT REQUIRED
The SmartChannel® Microchannel Fabrication Kit provides the components required to prepare PDMS microchannel devices.
Materials
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PDMS elastomer and curing agent
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4Dcell epoxy microchannel molds
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Graduated plastic cups and glass spatula
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Scalpel and adhesive tape
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3 mm diameter punches
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35 mm glass-bottom culture dishes
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Fibronectin coating solution
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Phosphate-buffered saline (PBS)
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Cell culture medium and cell suspension
Equipment
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Desiccator for PDMS degassing
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Oven capable of reaching 80°C
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Plasma cleaner for surface activation
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Standard cell culture equipment
Equipment requirements depend on the selected kit configuration.
The molding procedure described below uses 12 mL of PDMS elastomer and 1 mL of curing agent to prepare four chips.
STEP 1 - PDMS MIXING, MOLDING AND CURING
Follow the five video tutorials below to fabricate PDMS microchannels, from elastomer preparation and chip molding to glass bonding, surface coating and cell seeding.
1. Prepare the PDMS mixture
Add 12 mL of 4Dcell PDMS elastomer to a graduated plastic cup, followed by 1 mL of curing agent.
Mix thoroughly for 2 minutes using the glass spatula until the mixture is homogeneous.
Preparing and mixing the PDMS
2. Remove trapped air bubbles
Degas the mixture in a desiccator for approximately 10 minutes. Alternatively, leave the mixture at room temperature for at least 1 hour to allow air bubbles to escape.
3. Pour the PDMS into the mold
Carefully pour the mixture into the 4Dcell epoxy microchannel mold.
Degas again until no visible air bubbles remain.
Pouring and degassing PDMS in the microchannel mold
4. Cure the PDMS
Place the filled mold in an oven at 80°C for 1 hour.
Alternatively, allow the PDMS to cure at room temperature for approximately 8 hours.
5. Remove the molded chip
Allow the PDMS to cool before gently removing the chip from the mold, following the direction of the microchannels.
Avoid touching the microchannel surface, including with gloves, as contamination may interfere with subsequent bonding.
Curing and demolding the PDMS microchannel chip
6. Prepare the inlet and outlet ports
Remove dust particles from the PDMS surface using clean adhesive tape.
Using a 3 mm diameter punch, create holes at the channel inlet and outlet positions.
Punching the inlet and outlet ports
STEP 2 - BOND THE PDMS CHIP TO A GLASS-BOTTOM DISH
1. Prepare the surfaces
Place the molded PDMS chip and the glass-bottom dish inside the plasma cleaner, with the microchannel surface exposed.
2. Activate the surfaces
Apply plasma treatment for 2 minutes, following the equipment operating procedure.
3. Bond the PDMS to glass
Immediately after activation, position the PDMS chip at the center of the glass-bottom dish, with the microchannels facing the glass surface.
Gently press the chip against the glass, avoiding direct pressure on the microchannel structures.
4. Complete the bonding process
Place the assembled device in an oven at 80°C for 15 minutes.
Check that the PDMS chip is properly attached to the glass bottom before proceeding with cell culture.
Plasma activation and PDMS-to-glass bonding
STEP 3 - MICROCHANNEL COATING AND CELL SEEDING
1. Coat the microchannels
Add 20 µL of fibronectin coating solution to the microchannel inlet.
Allow the solution to enter the microchannels by capillary action and incubate for 30 minutes.
2. Wash and equilibrate the device
Thoroughly rinse the microchannels with PBS.
Add 3 mL of culture medium and incubate at 37°C for 15 minutes.
For sensitive cell types, the original protocol recommends an optional overnight pre-incubation with 3 mL of PBS at 37°C before cell seeding.
3. Introduce the cells
Remove the medium and place a 20 µL droplet of cell suspension at the microchannel inlet.
Gently tilt the device to facilitate cell entry into the channels.
Adjust cell concentration according to the cell type and desired initial seeding density.
4. Allow cell attachment
Incubate the device for 20 minutes at 37°C and 5% CO₂ to promote cell adhesion.
5. Add culture medium
Add 3 mL of culture medium to the glass-bottom dish and close the lid.
Return the device to the appropriate cell culture incubator.
6. Begin cell observation
For standard mammalian cell culture conditions, incubate overnight before observing cells within the microchannels using microscopy.
CRITICAL HANDLING POINTS & TROUBLESHOOTING
How to avoid air bubbles in PDMS microchannels
Degas the PDMS mixture before and after pouring it into the mold. Make sure no visible bubbles remain before curing, especially around the microchannel structures.
How to improve PDMS-to-glass bonding
Keep both bonding surfaces free of dust and contamination. Avoid touching the microchannel surface during handling and complete bonding immediately after surface activation.
What to do if cell loading is insufficient
Check that the coating solution and cell suspension enter the microchannels correctly. Adjust the cell suspension concentration and loading procedure according to the cell type, size and adhesion properties.
What should researchers consider when using PDMS for compound studies?
PDMS can absorb certain molecules from the surrounding medium. Researchers should consider potential compound–material interactions when designing experiments involving small molecules or interpreting exposure-dependent cellular responses.
FREQUENTLY ASKED QUESTIONS
EXPLORE SMARTCHANNEL® SOLUTIONS
Fabricate your own PDMS microchannels
The SmartChannel® Microchannel Fabrication Kit provides the materials and molds needed to produce microchannel devices in your laboratory, with access to different channel geometries for your experimental applications.
Prefer ready-to-use microchannels?
4Dcell also offers SmartChannel® Dishes with pre-bonded PDMS microchannels in glass-bottom culture dishes, reducing the preparation required before cell seeding.
For specific microchannel dimensions, geometries or experimental requirements, contact the 4Dcell team to discuss your application.