Public Lab Research note

Speck particle monitor

by chrisbartley |

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Speck is a low-cost particulate monitor currently under development by the CMU CREATE Lab as a tool for citizen science and personal exposure tracking. By combining maps and data visualization tools, we hope to enable communities and individuals to better understand and quantify the quality of the air they breathe.

Speck uses a Syhitech DSM501A, similar to the popular Shenyei PM sensor, but we have paired it with a small fan to pull air across the sensor. We found that the fan produces much better responsiveness and more signal than simply relying on the resistor's convection effect. To convert the sensor's stochastic readings to an actual reading, we did a machine learning-style parameter search to create a custom piecewise linear low-pass filter by comparing the Speck readings to a Hach MET ONE.



Initial results are encouraging, with the Speck producing readings for ~PM 2 particles which are recognizably similar to professional-grade sensors such as the MET ONE. We present here visualizations of two our our tests: a test with 144 specks arranged in 12x12 grid, and another with 64 Specks located in homes around Pittsburgh, PA for a period of five days.

12x12 Grid Test

We arranged 144 Specks in a 12 x 12 grid to test how particles flow through the room. We tested with a vacuum cleaner, an air purifier, and candles. The video below discusses the results and gives a brief demo of how to use the visualization.

We also encourage you to also explore the visualization for yourself (best viewed in Google Chrome).

In Home Test

We loaned 64 Specks to members of the CMU School of Computer Science community to put in their homes for five days. The Specks recorded samples once per minute. Once all Specks were returned, we created a visualization which combines geolocation with plots of the recorded data.


Please feel free to explore the results (best viewed in Google Chrome). Suggested exploration: set the "Show" filter to only show Specks located in the kitchen, and then slowly move the red, triangular cursor back and forth in the timeline to see changes in particles detected during typical mealtimes.


We're continuing to develop and improve the Speck, and are also developing a visualization portal for environmental sensor data.

indoor-air-quality-mapping particulate-sensing pittsburgh cmu visualization dust optical-sensor air-qualty particulate speck


Chris, Very nice device. And smart testing setups. The Explorables visualizations are fantastic. That will change the way people understand data sets. Do you have a target price point for Speck? I saw Illah's Engadget video with $50-$100 for AirBot and WaterBot. It looks like these are not open source. Does the Create Lab hope to partner with someone to manufacture them?
Excellent stuff. Chris

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Hi Chris! Thanks for the kind words. We are indeed working with a manufacturing partner for CATTFish (formerly WaterBot), but I don't know exact costs yet. For Speck (formerly AirBot), we're not quite as far along, still considering various options. The $50-$100 numbers in the Engadget article seem low for commercial product prices, at least for a first run--I imagine those numbers were for BOM and/or production in high quantities (tens of thousands).

That display is impressive.

I'll be quite crass and ask: would you like to donate any of these to some folks down in Reserve and Plaquemines Parish, Louisiana? It could mean a lot for folks who live in the shadow of Grain and Petroleum coke Export facilities. I'm currently making a DustDuino or two, in my spare time (which is mythical) but I can think of 7 communities in Louisiana who would want to deploy these to gather evidence that these facilities are making it hard to breathe around here.

I'll forward this to my roomate, a CMU alum in New Orleans.



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The Southwest Pennsylvania Environmental Health Project (SWP-EHP) is using the Speck to investigate effects of natural gas drilling in PA, they lend Specks out to individual homes for 2-4 weeks to gather data. They also provide free analysis support. The SWP project seems like a great model for others to emulate and as Scott E. indicates, folks in Louisiana could certainly benefit (thanks to Dvera Saxton for info on SWP-EHP).

The site mentions the device is still 'under development' but I've not been able to find info regarding availability, cost, etc. Any idea of this?

This is inspiring work Chris, thanks for posting!


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Exciting to see... What's the most minimal sensor we could create though? Could we just connect the pm sensor to an openlux ( and have it generate a colored light and connect to a laptop for data download?

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How much does the Syhitech DSM501A cost and are there plans or software for the Speck available? I know that CMU Create lab is open source which is really awesome.

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Data sheet for the sensor: tmp_DSM501A_Dust_Sensor630081629.pdf

I also found a couple places to buy it, but they don't show prices better than the listed Shenyei $15.80 or so: ($14) (no price, could be good if bought in quantity)

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So I'll try to answer some ?'s: The Shinyei was around $15- we tried that first. The Syhitech is something like $3 in reasonable quantities. So it's vastly cheaper and nearly identical when you look at them side by side. I don't know where the last place we bought them, but it was a many-weeks delivery time, probably offshore. We don't have DIY plans for how to make a speck- it's a real mold right now, but we want to work out a DIY process that deals with voltage regulation and light-tightness (these are what kill most attempts at this sensor usage). We do have a library of Specks- we just built a total of 300 to lend out- so if you are interested in borrowing some to try it out, of course that's what we are about. 150 are already out and about. If you are interested you can start by reaching out to me and I'll introduce you to the outreach folks in CREATE. Scott at healthy Gulf, we should easily be able to get you a couple to try out and see if it detects what you need it to detect.

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Hi Scott, Gerald and all.

Thanks for all the comments! The Speck is currently not commercially available, but could be very soon. Please sign up for our mailing list to stay tuned (just select the Speck check-box):

Also, our Gateway software for the Speck is free and open-source, and available at:

If you have any other questions about the Speck or want to inquire about borrowing a Speck for an interesting project/activity, please email us at

Cheers, Bea

Community Outreach Coordinator CREATE Lab

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Nice work. What sort of fan are you using to draw air across the sensor?

Also, if anyone visiting this page would like to do something like this themselves I made an Instructable with step by step instructions:

My setup isn't quite as sophisticated, but it posts the data to and isn't too complicated.

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alxmjo: Sorry about the delay in replying. Here is the digikey part number for the fan we use: 563-1111-ND. We checked out your DIY set up - glad to see it! You may want to shield the IR sensor from direct light though, so as not to cause interference.

Last week, @mathew and I worked on standard Open Pipe Kit drivers for a range of different optical dust sensors, to get them all feeding into We put one together for the Speck too, take a look:

Great idea and great monitoring! Please can you post some information about the software you use for the visualization of the data for the grid and home test?

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All the visualization software is custom stuff we developed at the CREATE Lab. The grapher in the demos is our BodyTrack grapher which we've now mostly replaced with a new version that supports WebGL (with a fallback to Canvas for browsers which don't support WebGL). The grid is a one-off, written just for that particular visualization.

Probably the best place to start learning about the grapher is with our wrapper library:

Hi there! still on this project? There's a Public Lab event coming up not too far from you in Morgantown WV. You should think about coming!

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