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Making a Breathalyzer — Parallax Forums

Making a Breathalyzer

BasicStamperBasicStamper Posts: 4
edited 2010-12-22 21:46 in BASIC Stamp
Is this the only part I am going to need?

http://www.parallax.com/Store/Sensors/GasSensors/tabid/843/CategoryID/91/List/0/SortField/0/Level/a/ProductID/695/Default.aspx

also along with that, how do I code in to use this module and how can I get the number back of the blood alcohol content under a debug command?

Comments

  • stamptrolstamptrol Posts: 1,731
    edited 2010-11-03 16:20
    Have you looked at the sample code and other documentation in the section you referenced?
  • BasicStamperBasicStamper Posts: 4
    edited 2010-11-03 20:51
    stamptrol wrote: »
    Have you looked at the sample code and other documentation in the section you referenced?

    yes I realized that was there after I posted, I'm still not sure how I would get the blood/alcohol level to display under a debug though
  • ercoerco Posts: 20,256
    edited 2010-11-04 12:59
    You can get one of these for $2.43 as a backup if you can wait 2 weeks for shipping!

    http://cgi.ebay.com/Digital-Alcohol-Breath-Tester-Analyzer-Breathalyzer-LCD-/250513073075?pt=LH_DefaultDomain_0&hash=item3a53be23b3
  • Ken GraceyKen Gracey Posts: 7,387
    edited 2010-11-04 13:02
    This idea would make a nice iPad/iPhone hardware product.
  • ercoerco Posts: 20,256
    edited 2010-11-04 13:20
    David Cassidy agrees!

    http://www.foxnews.com/entertainment/2010/11/04/partridge-family-star-david-cassidy-arrested-dui-report/
  • BasicStamperBasicStamper Posts: 4
    edited 2010-11-04 13:51
    couldn't exactly buy one, this is going to be a project for one of my classes so it needs to be built on the BOE board from parallax with the BS2
  • zoopydogsitzoopydogsit Posts: 174
    edited 2010-11-04 13:54
    The problem with making your own or buying a cheapy from the Internet is callibration.
    Sure it _may_ be able to detect some presence of alcohol on your breath, but to determine blood volume, presumably whether or not that you are legally capable of driving may not be a good idea.

    I have a friend that bought a cheap one from eBay, after finding it didn't really work (he brought it to a dinner party where some folks were drinking others weren't) we then pulled it appart and found that it's active component was a low resistance device that was in an RC time like circuit, they measured it's change after someone blew across it, presumably looking for the evaporation rate of alcohol. Interesting approach, but that unit couldn't even tell the drinkers from the non drinkers, much less the blood alcohol level.

    Even if you can callibrate it against a standard (lets say you have a friend in law enforcement, and you can do some testing against a professional machine) there is still then the issue of predictability, that is, will it behave the same way every time under all conditions (after bouncing around in a car for six months, will it give the same reading?, what about a hot day or cold night or more importantly with different humidity levels?) etc. Normally scientific equipment have factoring (using devices like PTC or NTC thermisters to factor for temperature) for various conditions, they also have rigorous levels of testing to ensure a repeatable, predictable consistent outcome.

    I'm assuming from a pure physical standpoint you probably don't want the water from breath to get to the sensor, so you may want to put some kind of filter (tissue?) in the path. That in itself would be fun to play with.

    Having said that, it would certainly be a fun sensor to play with, would be great at parties, and there could be lots of interesting applications, such as having one in a car ceiling above the drivers head (assuming alcohol vapour will rise in a column of air), that if it detects any alcohol propts the user (by speech?) whether they are capable of driving.

    You could certainly develope a nice technical paper going through the issues of making it work and challenges of getting it repeatable.

    Sounds like fun :-)
  • ercoerco Posts: 20,256
    edited 2010-11-04 14:03
    @basicstamper: an interesting choice for a student project; how will you (responsibly) test & calibrate for a school project?
  • BasicStamperBasicStamper Posts: 4
    edited 2010-11-04 14:05
    Yeah this by no means needs to be 100% accurate, it is more or less just implimenting the function into a basic stamp, then using 3 LED as a kind of range for the sensor, and possibly a screen that counts from 5 to 0, or whatever amount of time you need to blow into the sensor to get a reading

    basically the calibration code is listed under the actual part, I'm just not sure how to impliment the device into what I will be doing, basically if I want to do an If statement that says if the alcohol is at this level then this led will turn on, how would I go about doing that is virtually my question

    and in response to erco, the calibration will just be that provided with the part, like I said it doesn't need to be 100% accurate as long as it can detect alcohol in breath and give me a reading, as far as testing I was planning on first trying mouth wash, and if that does not work then I planned on making a youtube video of us bringing it to a bar or a house party etc, and taking the video of us showing how it actually functions

    the class is supposed to be fun, and an elective, plus my professor has approved it so I would imagine he knows what will be done to test it
  • idrisbidrisb Posts: 5
    edited 2010-12-22 21:46
    hey did you ever get the breathalyzer to work and what kind of micro controller did you use. i am trying to build a breeathalyzer watch for my senior design class. when you bought the sensor module how many did you purchase
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