Air Wick Odor Detect teardown


[Hunter’s] wife came home from her latest extreme couponing session with a handful of free Air Wick Odor Detect air fresheners, and since they had so many of the things sitting around, he was compelled to take one apart to see what makes them tick.

The casing was secured with melted snap tabs which had to be cut, making disassembly a one-way street. Once opened, he found a trio of white label AA cells and an ARNIE COMPACT3 ISS.4 controller board, complete with an epoxy-sealed microcontroller. A similarly branded sensor board was attached to the controller, and he spotted a solenoid with a built-in nozzle for spraying air freshener as well.

The sensor board piqued his curiosity the most, and after some research he’s pretty sure that the Air Wick uses an Applied Sensor VOC air quality module to get the job done. The tiny sensor uses a special substrate containing electrodes, which measure the resistance of the sensing layer while it is heated to upwards of 400° C.  A change in resistance lets the air freshener know that it’s time to handle the odoriferous emanations floating about.

Thanks to [Hunter] for taking the time to tear the Air Wick down and letting us know what’s inside!


  1. karl says:

    I love the term “human bio-effluence” in one of the documents he references about the sensor chip.

  2. Balloonman says:

    So, maybe we could use this sensor system to activate an exhaust fan system?

  3. Jorge says:

    Arduino fart detector on my radar!

  4. Martin D. says:

    I’m wondering if the sensor detects the odor of the air freshener…

  5. thelinuxone says:

    very interesting… i see a “stink-o-matic” tazer in my future…

  6. Spork says:

    I’m curious if you could use this sensor (or same design, lower temperature) to detect alcohol on someone’s breath.

    Would surely be a cheaper way to play that drunken breathalyzer game that HaD has featured in the past.

  7. AndroidCat says:

    Add those sensors to a mobile sentry-bot project: Track down odors and eliminate them!

  8. adam says:

    hey maybe I am stupid but does anyone else after reading this not understand exactly how the sensor works??? If someone could re-explain that for me that would completely awesome I just dont understand how heating the substrate up with a odor or with out a odor gives a different about resistance to a liquid.

  9. adam says:

    hey can anyone re explain how the sensor works?? I might just be an idiot but I dont understand how a liquid substrates resistance changes when there is a odor in the air weather it is heated or not.

  10. Zee says:

    No adam you’re not stupid I don’t get it either. How do odors cause a change in resistance?

  11. Oren Beck says:

    NICE job of teardown and part research!

    @Spork: It’s quite possible in basic concept. the details of having to Hack things like whatever parameters tune that sensor’s detection curve may be non-trivial. Will it “as is” detect Ethanol or exhaled Ketones Aldehydes? That might need some experimenting:>

    while fact checking my memory of the sensors in Hunter’s Blog post, and your query re Ethanol.. I tripped across:

    Wohoo- we might Hack a Cancer Detector out of a perfume pot!

  12. Interesting, never knew how many parts there were in one of those things.

    Yes the alcohol sensors are broadly similar, they use a pair of heating elements where one is shielded and the other isn’t and a Wheatstone bridge to measure the difference.

  13. therian says:

    how does sensor discriminate air-freshener ?

  14. jim says:

    turns out if you discharge a large enough capacitor across the sensor, everybody in the room briefly smells the worst fart ever and dies

  15. Mike says:

    I’m with Martin D on this, I don’t see how this thing wouldn’t just catch itself in an infinite loop. I know the marketing department wants us to think that the product “eliminates odour” but it obviously just masks odours with stronger laboratory designed “pleasing” odours.

    I admit, I’m a bit disappointed to actually see sensors in this thing. I was really hoping it just went off randomly. :)

  16. echodelta says:

    Fresh air is not full of chemicals (stink bomb)! The fan switch on is a good idea. How about a fart meter where amplitude is measured and displayed. Beans anyone?

  17. Paul Potter says:

    I’d wondered how these worked. Hoping to see some great builds using that sensor etc.

  18. Vampyredh says:

    OOOh I got one for this. Make them in childrens underwear for when they crap only have it hooked to a pad that zaps em when they do it. Lmao hey if it works for dogs why not kids lmfao……No I am just kidding all in humor folks I neither condone or approve the torture of innocent children or animals.

  19. Oren Beck says:

    Actually- you’ve invoked an echo of my “bark trainer” Hack’s sentiment.

    Don’t shock the kid- it’s not their fault might be a summary?

    My hack on bark collars- Microphone+transmitter on Dog. Receiver and shocker on OWNER. I predict enhanced bark control. We can dream, can’t we?

    RE: Sensing of “personal odors” and related.

    There’s a tragic reality of some people literally not knowing they’ve got problems like diabetic ketosis for example. And in some cases it’s life threatening if undetected. Most folks with medical conditions have some other warnings but anything that gives forewarning can be a Very Good Thing

  20. hunter says:

    it looks like those crafty germans beat me to it as far back as june. go google translate!

  21. Marcin says:

    It can be used in car to immediately turn off ventilation, when detecting odor or smoke outside.

  22. none says:

    The link to the blog is dead!?

  23. Mandy says:

    Joking aside it would be GREAT if it could be adapted as a poo alarm!
    We have an autistic son and I’ve spent hours on the internet trying to work out some alarm we could fit in his bedroom to alarm us of this.
    He doesn’t wear a nappy during the day but get’s safely wrapped up still in a nappy & all in one PJs at night.
    There must also be a use for some parents of babies, or for people litter training puppies/kittens!
    IF anyone has any ideas or knows of any alarms coming, would be great to hear.

  24. Lee Mitchell says:

    I am a tech and all the technology in this product is useless.
    I was looking forward to the technology doing its job but NO.
    No one has mentioned the rfact that the product simply DOESNT WORK.
    We have bought several units and placed them at the rear of the shop where we change the babys nappy, to no avail. It doesnt matter how bad the nappy is this product from airwick does not detect or spray when the nappy is changed of after.
    I tried it in a small room in which 4 11 year old boys were sleeping and farting all night with the door closed NOTHING not a squirt.
    Truly a disapointment from airwick.

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