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Jan 13

Pimp My Spin Coater

by mitch | Categories: chemical electronics, materials chemistry | (16646 Views)

My research has recently involved the process of spin coating, and being in a nuclear chemistry group we of course don’t have a spin-coater lying around. So, I’ve been hiking up the hill to use the Somorjai group‘s spin-coater. This past week I decided I wanted my own spin-coater and so I set about making my own. The working model is shown below.


Spin-Coater in the Dark: Lights are turned off for more dramatic effect.

If you’re going to start making your own lab equipment you might as well trick out the new hardware. In that spirit, my spin coater has 3 light emitting diodes: a green one, a red one, and a blue one. I can vary the revolution per minute from ~500rpm to ~2500rpm by varying the voltage I supply to the spin coater. The sample is mounted in the center and is stuck to the spin coater by Velcro, this can be more easily seen in the next photo.


Spin Coater Close Up

As can also be seen in the photo, my spin coater is just a regular pc fan I bought at CompUSA this past Wednesday. I monitor the speed of the spin coater with a laser mounted above the spin-coater that shines through the fan’s blades and strikes one of our group’s alpha detectors. The nice thing about the alpha detector is that I don’t even have to supply any power to it. There is enough current generated, I presume by the photoelectric effect, to carry a signal to an oscilloscope which I can use to monitor the fan’s speed. A picture of the laser, which is my boss’s laser pointer he uses for talks, is seen in the next photo at the top of our group’s only non-radioactive chemistry hood.


Spin-Coater in the Hood

It took me 2 days to build my spin coater, Wednesday and Thursday, and one more day to make sure it calibrates properly, Friday. The total amount in extra costs was $20 for the spin-coater(pc fan) all the rest of the equipment we had lying around.

Now what other lab equipment could use some LEDs? Hmmm….

Note 1: Paper that first got me interested in using a pc fan: Spin-Coating of Polystyrene Thin Films as an Advanced Undergraduate Experiment

Mitch




11 comments

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  1. Suvy S

    Hey, i was kinda interested in your Spin COater and wanted to build one by myself. What are the specs of your coater as in what is the power of the fan you are using and how are you holding down the sample without using a suction pump??? Are you doing it with a two sided scotch tape???

  2. mitch

    I use velcro to hold the samples down. The pc fan is an Antec tricolor pc fan. It takes DC Power, we can vary it from 0-12V depending what speed is needed. The fan was able to spin from 0 rpm up to around 2500 rpm.

  3. ChemE

    Do you have any issues with solvent flying off the sample at start up? That said, building a case wouldn’t be very hard. Perhaps out of acrylic with Lichtenberg figures?

    1. mitch

      Yeah, there is a sling problem. I just wrapped aluminum foil around it. This obviously isn’t a permanent setup, but we’ve gotten a few papers out of this setup.

  4. Adrian

    Have you tried using a fan with a built-in speed sensor? Three-wire PC fans, from my understanding, use the third wire as an RPM sensor lead. You could incorporate this and skip using the laser/opto altogether :)

    I’m planning to experiment using PC fans as galvos for a DIY laser XY scanner to project images on a wall. I theorize that the variable speed can be utilized in the same way as a stepper galvo, and just base the laser pulses upon the two fans’ rotational speeds.. Maybe it will work..

  5. mitch

    @Adrian, I assume you would still have to calibrate the 3rd lead. It probably isn’t spitting out a digital signal.

  6. Nilux

    Hi
    I am planing to make my own spin coater.
    Spin tell me about ur spin coater specification?
    why u have used different color LED and i like to know about alpha sensor and its working and specification ..?
    Do u have any sketch of ur spin coater then plz forward it on my email id.??

  7. adel

    awesome, how can i calculate speed rotation from the applied voltage

    1. Mitch

      You need to calibrate it. I used a laser striking a photodiode and read the output on an oscilloscope.

  8. Claire

    Thanks for this Mitch I need a spin coater for my research and the Uni doesnt have one – this looks like a solution Claire

    1. mitch

      No problem. Let me know if you run into any difficulties.

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