25 july 2008

What was done

After being briefed about the status of our project the previous week, we proceed with our trial and error in making the micro channel chip usingthe SU-8.

This week focuses on finding the proper way to develop the SU-8 photoresist without affecting the chemical.

We started off by putting the glass pieces under UV light in which a stencil is placed over it to get the desired design that we wanted. This procedure is called UV masking.

Following that, the glass pieces were then heated up again. A point to note is that the heating up of the glass pieces in the oven SHOULD take place immediately after the UV masking. This step is called the post exposure bake.

Following that, the glass pieces were then left fully submerged in a beaker of the SU-8 developer. The glass pieces were then rinsed with tap water for about 10 seconds before being soaked into a beaker of Isopropyl Alcohol (APA) for another 10 seconds.

The end product

Recommended program:

UV masking
We used a stronger UV light machine. Thus, the energy emitted was 150-160MJ in which the glass pieces were exposed for a time of 13 seconds.

Post Exposure Bake
The glass pieces were heated in the oven for 1o minutes.

Developing
This took some time for perfection as the SU-8 always comes of for the first few runs. But we managed to get it right after several tries. The glass pieces should be soaked in the developer for 10 minutes. Not longer than 11 minutes.

Conclusion

For an experiment that was full of trial and error, we did quite well as we managed to find the proper timings in making a good mico channel chip. Though this week was quite a success since we exceed expectations in finding the right blend of timings, we should not be too complacent. This is due to the fact that we have yet to find a way to stick the glass pieces together without melting the micro channels form on the glass pieces. Till then, we have to be constantly be on our toes.