Putting on your science gown

03/30/2015

On the second floor of MEB, through the doors labeled 200 and down the hall, you can find our very own Micro-Nano-Mechanical Systems lab. The MNMS lab was started by the late MechSE professor Mark Shannon over 20 years ago.

This red chemical called photoresist is applied to a substrate using the spinner.
This red chemical called photoresist is applied to a substrate using the spinner.
The lab is mainly used for photolithography and other related processes. Photolithography uses light in reaction with a red chemical called photoresist to put patterns on a substrate (solid substance). The substrate is first coated with a thin film of material, and then coated again with the photoresist. Light is projected through a photomask so that it shines on the photoresist in a specific pattern. The photoresist reacts with the light and creates the pattern in the film. After the photoresist and excess film are removed, what’s left on the substrate is the patterned film. ME 487 uses this process to put gold film on silicon and create tiny pressure sensors.

Gown required for the clean lab.
Gown required for the clean lab.
Entering the lab is its own process. You start in a little chamber outside the gown room, where you put blue booties over your shoes. The booties cannot touch the ground, so once they are on your feet you must stand on a special blue matt- kinda like playing hot lava monster. Next you go into the gown room. There you put on a hairnet (called a bouffant) and a face veil that goes over your nose. Then you put a hood on over your head so that only your eyes are exposed. Next comes the gown itself, which is basically a bunny suit without feet. You pull latex gloves over your sleeves up to your elbows, and put a second pair of booties on your feet and over the bottoms of the gown legs. The hood has a flap that goes down the collar of the gown to seal the gap at your neck.  The last thing to go on is a pair of safety goggles, at which point you are basically completely covered. Then you take a 15-second air shower to remove any excess particles from your suit, and you’re free to enter the lab through the other end of the shower.

Anything you bring into the lab has to be cleaned off as well. You can put small objects in a pass way after they’ve been cleaned and then get them from inside the lab. Ever wonder why there’s a liquid nitrogen tank covered with ice outside MEB? That’s the feed for the nitrogen gas hoses used to clean off objects for the clean lab. Less sensitive objects like maintenance tools get wiped down with isopropyl alcohol, which is also used to clean surfaces in the lab.

A pressure sensor (right) and microfluidic mixer, both manufactured in the clean lab.
A pressure sensor (right) and microfluidic mixer, both manufactured in the clean lab.
The lab is divided into a yellow side and a white side. The yellow side is Class 100, which means that there are a maximum of 100 particles per cubic foot of space (particle size = ~.5 microns). The white side is Class 1000. Air is constantly circulated through the lab, causing excess particles to eventually get pushed out due to the positive pressure. Other measures are also taken to help limit the number of particles. You have to use special paper (it has latex in it and doesn’t flake as much as normal paper), and gamma irradiated pens with ink that doesn’t spill excess particles.

There are five students who currently work in the lab. One of them, engineering mechanics major Lee Yi, says working in the lab has provided him with unique learning opportunities. “I’ve gotten to learn a lot about photolithography and etching,” he said. “This job has also given me a chance to learn about and use equipment that I wouldn’t have had otherwise.”

The yellow side of the clean lab. Yellow indicates 100 particles maximum in each cubic foot of air space.
The yellow side of the clean lab. Yellow indicates 100 particles maximum in each cubic foot of air space.

The clean lab is often used by MatSE, MechSE, and ECE engineers, as well as food and crop sciences majors. Professors will often sponsor their undergrad and grad assistants to use the lab for research projects (usage costs $60 per day). The lab can accommodate a wide variety of projects including gyroscopes, polymers, biomaterials, and krona treatment (using plasma to change the surface tension of a material). It’s open 24-7 and is available for use by any students on campus, providing that each student does online training and passes a test in the lab on how to use the equipment. 

 

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