Question

Draw a process flowchart to fabricate PDMS based microfluidic device with 3 channels. The device has 3 inlets and 3 outlets. The channel dimension are Length=5mm, Width=5mm, and Height=50μm. How this device can be functionalized with antibodies (such as anti-CD4 Antibodies) to capture CD4 cells from blood

Answer 1

As I have a same experience of fabrication of microfluidics channel in PDMS, I can suggest you a simple way to do so. Hopefully this will be helpful.

Here, you can use firstly lithography and then pattern transfer in PDMS.

Details steps are given below with diagrams.

Step 1: take a substrate (Si is common) . Process all cleaning step and clean it.

Step 2: Using spin coater, coat substrate with SU-8 2100.

Step 3: channel mask should be made before. (According to instrument availability, I used to do this with maskless lithography system, so I didn't need a hard mask)

Step 4: complete lithography steps with channel mask . All step should be performed like prebake , exposure, postbake , development and hard bake. After lithography channel pattern should be fabricated over substrate. Now we have Channel pattern on a substrate. Sprey silicone oil on it. So that PDMS do not stick to it while pattern transfering.

Step 5: now put substrate in a petridish and pour mixture of PDMS and diluter over it. Whole pattern should be covered with PDMS solution. Bubbles may be present there but dont worry they will be removed during curing process.

Step 6: put this petridish in desiccator with vaccuum pump on for more then 2 hours. Then place desiccator for settlement of PDMS over night with vaccuum in it.

Step 7: remove petridish from desiccator and peel PDMS from substrate. Now channel pattern must be copied in PDMS.

You can cover this channel with another PDMS thin sheet.

I have attached an image showing some steps for a single channel . You can proceed with your own channel design.

Hopefully you will understand my process.

Thanks