NateDawg
Posts: 3
Joined: Fri Jun 15, 2018 11:23 am

Detect presence of poison

Fri Jun 15, 2018 11:25 am

Hi guys

I've been thinking about a project whereby you could automatically detect the presence of poisonous substances using a Pi + sensors

Does anybody have any idea where to start with this?

jamesh
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Re: Detect presence of poison

Fri Jun 15, 2018 11:50 am

The really difficult bit is the sensors. Usually once you have the right sensor, they are pretty simple to plug in to the Pi.
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NateDawg
Posts: 3
Joined: Fri Jun 15, 2018 11:23 am

Re: Detect presence of poison

Fri Jun 15, 2018 11:58 am

HI jamesh, any ideas if there is something that could accomplish this? Or if there is a way to develop something like that?

scotty101
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Joined: Fri Jun 08, 2012 6:03 pm

Re: Detect presence of poison

Fri Jun 15, 2018 12:17 pm

What type of poison do you want to detect? Airborne? in a liquid? on a surface?

They will all have different chemical 'signatures' which will react/interact with different sensor types in different ways to indicate their presence.
The closest device to a 'universal detector' would be something like a mass spectrometer which usually isn't a portable/cheap device.
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Pi Interests: Home Automation, IOT, Python and Tkinter

jamesh
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Raspberry Pi Engineer & Forum Moderator
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Re: Detect presence of poison

Fri Jun 15, 2018 12:24 pm

NateDawg wrote:
Fri Jun 15, 2018 11:58 am
HI jamesh, any ideas if there is something that could accomplish this? Or if there is a way to develop something like that?
I can only suggest Google, which after a very quick search, brought up only chemical kits rather than electronic detectors. You;d need to investigate a bit more thoroughly. There have been recent advances in sold state detectors for chemical compounds, so there might be something out there, but it won't be cheap.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
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klricks
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Re: Detect presence of poison

Fri Jun 15, 2018 12:25 pm

NateDawg wrote:
Fri Jun 15, 2018 11:25 am
Hi guys

I've been thinking about a project whereby you could automatically detect the presence of poisonous substances using a Pi + sensors

Does anybody have any idea where to start with this?
Your request is much to vague...... There are thousands of substances that could be considered poisonous. Many of them very difficult and/or expensive to detect. You need to choose 1 and see what Google has to say about it...... Find a sensor if one exists.... Then ask about how to connect to the Rpi.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Stretch w/ Desktop OS.

NateDawg
Posts: 3
Joined: Fri Jun 15, 2018 11:23 am

Re: Detect presence of poison

Fri Jun 15, 2018 12:35 pm

Thanks for the replies, the substance is typically granular, almost like small seeds and has a slight sulphury smell

The particular substance in question is called temik/aldicarb and is used to poison animals, i'd like to develop (or at least try to develop) some way of preventing animals from ingesting it

scotty101
Posts: 2909
Joined: Fri Jun 08, 2012 6:03 pm

Re: Detect presence of poison

Fri Jun 15, 2018 12:39 pm

You may find this interesting
https://www.osha.gov/dts/sltc/methods/o ... rg074.html

Not a hobbyist project really unless you are really motivated/skilled.
Electronic and Computer Engineer
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Gavinmc42
Posts: 2033
Joined: Wed Aug 28, 2013 3:31 am

Re: Detect presence of poison

Fri Jun 15, 2018 1:21 pm

I have come across a few ways at work just because I work at a Uni ;)

A reagent reacts to the compound and changes colour, ie fancy litmus paper.
Think pregnancy test method.

A PCR replicates DNA until there is enough to be detected by stokes shift florescence.
FYI, Pi's Zero's make good PCR controllers, hint - avoid Linux ;)
As Jamesh says, it is all in the sensor, even Adafruit now sell the "right" sensor.

NMR, uses magnetic resonance of old numbered protons.
Typically the Hydrogen in water and Carbon13 in organic compounds.
You can make you own NMR, I have yet to make a Pi controlled one, no one has asked yet :(
Depending on the strength of the magnets, more complex molecules can be analyzed.

Higher magnetic fields determines the resonance frequency.
Earths magnetic field is a few KHz, DIY ones on YouTube
Benchtop ones at 80MHz with rare earth magnets.
Superconductive magnets in liquid Nitrogen/Helium 300 to 800MHz.

A Pi based one should be able to do 1KHz to 10MHz without getting too fancy.

Gas chromatography is used in that paper.
Yep Google say you can DIY with a Arduino ;)
Use a bit of DVD and Pi Camera to make a spectrometer?
https://publiclab.myshopify.com/collect ... 7504787563

Multispectral sensors are getting cheaper and better all the time, they are even putting them in Smart Phones now.
Most are i2c based.
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