Question: Creating a "videocamera" for passive dust collection over time?

natematias is asking a question about air-sampling
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by natematias | January 14, 2023 18:44 | #38041

Hi everyone,

I'm wondering if anyone has advice or pointers on acquiring or creating a device that can record passive dust collection over time while I am riding by bicycle, maybe on a reel of some kind? I'm very grateful to the community for this guide on passive dust collection.

Context: I'm organizing a bike tour through the San Joaquin Valley in California. If it all comes together, we will be doing some storytelling and mediamaking about environmental justice questions, including air quality.

I'm interested to bring along a device that does passive collection particulate matter along the way. In the ideal case, it would be possible to identify roughly when we encountered the particles. The system does not need to correlate closely to other monitoring technologies, though it would be nice if it were internally consistent with its own observations, controlling for bicycle speed.

Is anyone aware of a system or design for a passive particle collector that can record particles onto a reel, and is reliable/small enough to bring on a 700+ mile bicycle ride? If I need to do it on a DIY basis, I've been thinking about speed-modding a cassette player to make it very slow, cutting open an aperture in the side of the case, and adding sticky tape reels instead of a cassette. I would then point the aperture forward when riding the bicycle.

But if someone else has already solved this, I would love to hear ideas!

Note: I am a social scientist who knows a lot about statistics & code, and a few things about air pollution. I can fumble around electronics well enough to mod a system, but not really design or create something new from scratch.


Here's an in-progress prototype. IMG_6817.jpg

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This looks v cool! Walkman style. I wonder how recoverable/measurable dust is from the tape when rolled up again.

Would some kind of clock mechanism be a better bet for winding? But I'm also tempted by the cassette enclosure itself - easy to store in a dust-free environment, enclosed. I wonder if you actually loaded a very thin string of sticky tape onto a cassette, is there a way to make it not jam... you can buy thin tape, too. Then it's locked away and protected and you can unload easily.

You could point a little fan into where the tape is free. Maybe you could route it diagonally across the little window between the spools, to avoid gumming up the different pins it'd normally touch on the way around, and then cut out the window, so you can direct air across it?

Would riding the bike faster gather more dust, and affect your readings? or are you interested in the type of dust and the quantity doesn't matter as much?

I want to say I think dust collection usually means visual classification/quantification of the dust, which is pretty labor intensive. But if it's on a spool, maybe you could spool it back across a microscope and record an image sequence automatically, and somehow do particle detection on those images? A lot of unknowns, but there have been some efforts to automate image detection in images: #particle-imaging

What if you drove it from an odometer somehow... so the particles would be collected at a rate proportional to your travel distance? OK, now I'm overthinking things!

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