Custom Shield - Indoor Air Quality Monitor


That is very cool @anthonywebb - thanks for sharing.

  • Pity its not open source because it would be interesting to see what sensors they are using since the price is very good.
  • It looks like it is less than 3 inches wide so they are not using the “enormous” 6 inch Sinyei dust sensor. I would guess they are not using a particle counter since you can point the sensor at things to take a reading.
  • It looks like it is not wireless, but USB. Maybe they should add a pledge level including a 50 foot USB cable so I can check the smell in my basement :smile:

Some more details about the airboxlab device including photos of the PCBs :
Airboxlab blog


Here is another project I found :


  • Mostly for detecting VOCs
  • Uses Zigbee instead of Wi-Fi
  • Needs a base station to connect to the internet
  • Battery powered up to 2 months between charges
  • $249 for 2
  • Says it contains an accelerometer, not sure why that is - perhaps for detecting earthquakes ?



Fascinating - there was a wireless smoke detector in 2008 called the Canary where the special feature was that it could trigger your neighbors Canary alarm too in the event of a fire!! I don’t think it was ever manufactured though.

I like the feature that it will message you that the battery needs to be replaced - the battery low indicator peeped all day at my house one time and it freaked my dogs out. They trashed my bathroom and broke a bunch of stuff.

I will follow them to see if they make a product - I like the form factor of it more than any others I have seen.


It looks like your MICS-5525 sensor is superior for detecting CO.
The MQ series seems to be aimed at the hobby market.
Both have similar prices.

MICS-5525 detects from 10ppm, requires preheating for 4 hours before first use.

MQ-7 detects from 20ppm, it requires preheating for 24 hours before first use.

MQ-9 detects from 10ppm, detects methane, propane and LPG. Requires preheating for 24 hours before first use.

The MQ series are mostly attractive because of the standard sockets but it seems they are tricky to calibrate.

Detecting at 10ppm is good for health reasons. Home CO detectors are not supposed to alarm below 70ppm.


I have come to the conclusion recently that the particle counter (PC) is an important addition to this shield. The PC is good for asthmatics and can be used to determine if you need to get an air purifier and what setting the purifier should be set to.

I bought a particle counter recently and Im finding the readings very interesting. One of my pets has been having respiritory distress lately and whenever he is rasping I take a count and the PC is always above a particular level. I then take him outside or max the air purifier and he stops rasping. My wife thought it was a food allergy all this time.


Looks like SparkFun has one that’s a bit more affordable than the PPD42NS:


Also, just found a fantastic component for the MQ sensors:

This might make it possible to plug and unplug MQ gas sensors on the fly


What about this Grove sensor instead of your Sharp sensor - its only a couple of dollars more ?

Grove Dust Sensor Purchase

Chris Nafis who has researched these devices quite a lot seems to think it is a better sensor :

Chris Nafis opinion of the Grove Sensor :!topic/airqualityegg/dc5VTX7V8yI

The Sharp dust sensor fits nicely into the inexpensive radiation
shield. Unfortunately, the Grove dust sensor (which I think is MUCH
better) does not :frowning:

He also says that the Sharp sensor is better suited to outdoors :

it is clear that the sharp sensor
correlates well for high particle count environments. For indoor applications it mostly sees noise

Its also only 3 pins.


Sorry for the long absence here; been a bit slogged down with the Core re-design, once again.

I think the Grove dust sensor looks good; I’ll add a port for it to the Shield.

So therefore the Shield will include:

  • The Figaro TGS2602 sensor
  • The DHT22 temperature/humidity sensor
  • The MICS-5525 carbon monoxide sensor
  • 2x ports for MQ sensors
  • A port for the Grove Dust Sensor
  • A ‘calibration’ button for calibrating the sensors
  • One RGB LED, to display ‘air quality’ as defined by the user. Perhaps we can create some smart defaults for how this behaves. Would be great to have one LED per sensor, but unfortunately we’re running short on pins.
  • An attachment for a 3.7V battery

How’s that sound? @rockvole, ready to lock it down so we can start designing it?


@zach the components on the shield look excellent - better than I hoped for :smiley:


A question about the battery attachment - what kind of connector is it ? (e.g. does it require soldering or is it a standard part?)


They launched the Canary on Indiegogo - the form factor which I liked is gone.
They are also downplaying its air quality features and touting it as more of a home security system.

[Canary In Depth][1]

I hope it succeeds, but personally I would prefer a device which did one thing very well than a device which tries to do some air quality monitoring / home security / letting you know when to change your thermostats.

EDIT : Oops it looks like this is not the same company as the other Canary. I just assumed it was because it has the same name and the same air quality sensors.

This also has an accelerometer ?!
I guess that could be used to record when the device moved location which could be useful. Maybe accelerometers are just super cheap to incorporate now so they get added a lot.


It is a Molex-type connector; no soldering necessary.


Ok, great. When do you think you will be able to start work on this shield ?
I know you are busy :wink:


Soon! We’re focusing right now on re-designing the main 4 shields because we have to get the orders in for the components, since they’re being made in relatively large quantities (1000-2000 units each).

Once we’ve finished that, we’ll move onto the Custom Shields - they have much shorter lead times because we’ll be producing them in smaller quantities, at least to start.


Ok, sounds good Zach.


Thanks for your patience :smiley:


@zach, @anthonywebb, @loudbit

I found an interesting paper where researchers from Carnegie Mellon built a wireless air quality monitor and installed it in some peoples homes to see what they would do with the information.

One surprise is it looks like this could be one of the best ways ever invented to get people to give up smoking :slight_smile:

inAir Research Paper

Eric Paulos Professor at Berkeley Website


Guys, I know the component list is almost finished but I had a chat with a friend who told me that a UV sensor is extremely cheap and some people is obsessed about protecting their skin so although not exactly “air” quality it changes everyday so maybe if it’s easy can be made a last minute addition.