air pollution particulate sensor package

Guest
Hi,

This message is related to my earlier request for advice in the topic 'finding electronics design and fabrication expertise for a project'.

Because of the kindness of the group members here, I am posting more details about the project and aims.

The overall aim is to develop and deploy inexpensive 'personal' air pollution monitors. For the environment in which I am interested, a major pollutant concern is particulates arising from biomass combustion, coal burning, and car exhaust.

Although these may be inconsistent aims, I am interested in having a device that...
- can measure particulate concentrations (and perhaps temperature and humidity levels)
- is low cost, so that many devices can be deployed within a constrained project budget
- has a good degree of concordance (at least qualitatively) with accurate stationary monitoring stations
- can be read with an app on a cellphone or similar device (bluetooth?)
- is convenient to the wearer of the device, e.g, is robust and has the ability to run on batteries for a few days at a time

I anticipate that a user (or environmental health scientist or health care professional guiding the users) might want to record reading at several points during the day, not continuously.

There are several projects I have found on the web focused on devices to quantify particulates in the air, but I don't think that they satisfy the aims above.

The closest instrument that I could find is detailed in a PhD dissertation by David Holstius, a chapter of which I have posted here:

https://www.dropbox.com/s/azs0dqzgpffppl1/Holstius2014dissertation_Ch3.pdf

Because of my lack of training in the field of electronics, I do not know if the detection method, components, and overall design chosen by this individual would be appropriate as a starting platform to achieve the aims above.

Any input or suggestions would be greatly appreciated.

Thank you again.

-gyro
 
You forgot to put that in your public directory so we cannot see it yet. I do have a better idea what you are talking about now.

You want to detect particulate matter in the air, and this is going to be optically because you just do not have many other choices.

Here is the problem, mathematically, from zero to 100 %, you must define 100 % as zero. Totaslly clean air is the setpoint, the zero, the reference. If the nibers do not start there, it will be hard to use them. It's like the audio example before, you don't say 99.7 % NOT distortion, you say 0.3 % distortion. Kinda flipped over. This is exactly the same in this case.

Take a calibrated light source. Then a detector. Whatever drop there is from the light source to the detector is the result. This is no all that easy. What's more, I doubt you will be able to do it on a smart phone. This requires hardware.

Now comes the $64 question, what kind of numbers do you want ? PPM of corbon particulates ? I would almost venture to say there is an off the shelf solution for that. In fact, what abput smoke detectors, but instead of feeding an alrm, feed it to meter or whatever. A buffer to get the levels you wanrt and then something to display the result.

If you need accuracy, then we are talking instrumentation. That is a bit harder than building a (n old style) TV set. I can do it a little bit but I am not great at it. I got a Wavetek 111 and I am not only impressed by its technology, but damn near enamoured. Fucker makes a sine wave out of a triangle at .05 % THD ! Frequency independent. Has a cool type of feedback circuit. It requies the input to be EXACLT the amplitude it expects. I just got into it like last year, but the damn thing was builtin 1 1970 !

Damn I am behind the times.

So, with your thing, I figure you should set the setpoint in a vacuum. Start with that. Whatever the output is at that point from the optical sensor then, consider that the setpoint.

Circuitry ? Well that is kinda like knowing when to use a PNP transistor instead of an NPN. It is flipped. Upside down or backwards, whatevr you want to call it.
 
Another thing is the wavelength of light you use in the detector. If you define the subjedct as particulate mattr that is VISIBLE, tha ti one thing. you oculd use UV or IR.

the main question here iss - what results do you want ? Exactly.
 
Den tirsdag den 1. juli 2014 00.27.52 UTC+2 skrev Robert Macy:
On Mon, 30 Jun 2014 15:08:14 -0700, Jim Thompson

To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:



On Mon, 30 Jun 2014 14:22:00 -0700, RobertMacy

robert.a.macy@gmail.com> wrote:



On Mon, 30 Jun 2014 13:43:17 -0700, John Larkin

jlarkin@highlandtechnology.com> wrote:



...snip...



Cars aren't bad. Diesels, in busses, trucks, and construction/farm

machinery, are.



I'm a bit skeptical about the evils of CO2, but particulates are nasty

for people and the planet.



Particulates melt snow, which is especially evil.



Cars aren't bad. What about thousands of brake linings turning to

powedery

dust at a Stop sign ??



Depends on whether the dust falls to the ground or is fine enough to

become airborne.



...Jim Thompson



From the way that stuff migrates all over the wheels on my car, I'd say

it's pretty 'airborne'



Remember when the linings were made of asbestos? Which subsequently have

been removed from the market. Coincidentally? after reports finding high

levels in lungs of people who live near stop signs vs middle of the

blocks, more open areas.
Click to expand...

it the particle size that's important, if they are big enough it is is just
dirt it is when they are small enough to get deep into the lungs and stay there is gets dangerous, like asbestos and according to some exhaust from modern high pressure diesels and gasoline direct injection



-Lasse
 
On Tuesday, 1 July 2014 06:58:53 UTC+10, jurb...@gmail.com wrote:
Another thing is the wavelength of light you use in the detector. If you define the subject as particulate matter that is VISIBLE, that is one thing. you could use UV or IR.

the main question here is - what results do you want ? Exactly.
Click to expand...

http://en.wikipedia.org/wiki/Light_scattering

Rayleigh scattering is intensely wavelength dependent - to the sixth power of the particle diameter, and inversely proportional to the fourth power of wavelength.

It would be fun to use a bunch of light sources to measure scattering at a number of different wavelengths, and deconvolute the results to say something about the concentrations and sizes of the different particles doing the scattering.

You'd need Phil Hobbs to make it work ...

--
Bill Sloman, Sydney
 
On Mon, 30 Jun 2014 12:05:42 -0700 (PDT), gyromagnetic@gmail.com
wrote:

Hi,

This message is related to my earlier request for advice in the topic 'finding electronics design and fabrication expertise for a project'.

Because of the kindness of the group members here, I am posting more details about the project and aims.

The overall aim is to develop and deploy inexpensive 'personal' air pollution monitors. For the environment in which I am interested, a major pollutant concern is particulates arising from biomass combustion, coal burning, and car exhaust.
Click to expand...

Cars aren't bad. Diesels, in busses, trucks, and construction/farm
machinery, are.

I'm a bit skeptical about the evils of CO2, but particulates are nasty
for people and the planet.

Particulates melt snow, which is especially evil.



--

John Larkin Highland Technology, Inc

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Mon, 30 Jun 2014 13:43:17 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:

...snip...

Cars aren't bad. Diesels, in busses, trucks, and construction/farm
machinery, are.

I'm a bit skeptical about the evils of CO2, but particulates are nasty
for people and the planet.

Particulates melt snow, which is especially evil.
Click to expand...

Cars aren't bad. What about thousands of brake linings turning to powedery
dust at a Stop sign ??
 
On Mon, 30 Jun 2014 12:05:42 -0700, <gyromagnetic@gmail.com> wrote:

...snip....

https://www.dropbox.com/s/azs0dqzgpffppl1/Holstius2014dissertation_Ch3.pdf

...snip...
Click to expand...

Epithets deleted! that dropbox keeps squirreling around inside my system
and trying to do something, searching for things?

Twice that URL crashed my system [now THAT's malware control!, simply
crash if someone tries to muck about]

(I think dropbox got upset when I wouldn't sign up)

Anybody have a 'clean' URL for this?
 
On Mon, 30 Jun 2014 14:22:00 -0700, RobertMacy
<robert.a.macy@gmail.com> wrote:

On Mon, 30 Jun 2014 13:43:17 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

...snip...

Cars aren't bad. Diesels, in busses, trucks, and construction/farm
machinery, are.

I'm a bit skeptical about the evils of CO2, but particulates are nasty
for people and the planet.

Particulates melt snow, which is especially evil.

Cars aren't bad. What about thousands of brake linings turning to powedery
dust at a Stop sign ??
Click to expand...

Depends on whether the dust falls to the ground or is fine enough to
become airborne.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Mon, 30 Jun 2014 14:22:00 -0700, RobertMacy
<robert.a.macy@gmail.com> wrote:

On Mon, 30 Jun 2014 13:43:17 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

...snip...

Cars aren't bad. Diesels, in busses, trucks, and construction/farm
machinery, are.

I'm a bit skeptical about the evils of CO2, but particulates are nasty
for people and the planet.

Particulates melt snow, which is especially evil.

Cars aren't bad. What about thousands of brake linings turning to powedery
dust at a Stop sign ??
Click to expand...

Probably bigger particles. It's the really tiny stuff, like 100 nm,
that makes it deep into your lungs.


--

John Larkin Highland Technology, Inc

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On 6/30/2014 5:22 PM, RobertMacy wrote:
On Mon, 30 Jun 2014 13:43:17 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

...snip...

Cars aren't bad. Diesels, in busses, trucks, and construction/farm
machinery, are.

I'm a bit skeptical about the evils of CO2, but particulates are nasty
for people and the planet.

Particulates melt snow, which is especially evil.

Cars aren't bad. What about thousands of brake linings turning to
powedery dust at a Stop sign ??
Click to expand...

The dust is pretty large compared with diesel smoke particles, so it
doesn't penetrate very far into your lungs. They got rid of the
asbestos awhile back, which was a pity. Chrysotile asbestos is nasty,
serpentine basically isn't.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:

You forgot to put that in your public directory so we cannot see it yet. I do have a better idea what you are talking about now.

You want to detect particulate matter in the air, and this is going to be optically because you just do not have many other choices.

Here is the problem, mathematically, from zero to 100 %, you must define 100 % as zero. Totaslly clean air is the setpoint, the zero, the reference. If the nibers do not start there, it will be hard to use them. It's like the audio example before, you don't say 99.7 % NOT distortion, you say 0.3 % distortion. Kinda flipped over. This is exactly the same in this case.

Take a calibrated light source. Then a detector. Whatever drop there is from the light source to the detector is the result.
Click to expand...

Unless you use reflection, like in an optical smoke detector. Then 0%
is the baseline. He could probably count individual particles.


--

John Larkin Highland Technology, Inc

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Mon, 30 Jun 2014 15:08:14 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Mon, 30 Jun 2014 14:22:00 -0700, RobertMacy
robert.a.macy@gmail.com> wrote:

On Mon, 30 Jun 2014 13:43:17 -0700, John Larkin
jlarkin@highlandtechnology.com> wrote:

...snip...

Cars aren't bad. Diesels, in busses, trucks, and construction/farm
machinery, are.

I'm a bit skeptical about the evils of CO2, but particulates are nasty
for people and the planet.

Particulates melt snow, which is especially evil.

Cars aren't bad. What about thousands of brake linings turning to
powedery
dust at a Stop sign ??

Depends on whether the dust falls to the ground or is fine enough to
become airborne.

...Jim Thompson
Click to expand...

From the way that stuff migrates all over the wheels on my car, I'd say
it's pretty 'airborne'

Remember when the linings were made of asbestos? Which subsequently have
been removed from the market. Coincidentally? after reports finding high
levels in lungs of people who live near stop signs vs middle of the
blocks, more open areas.
 
On 6/30/2014 6:16 PM, John Larkin wrote:
On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:

You forgot to put that in your public directory so we cannot see it yet. I do have a better idea what you are talking about now.

You want to detect particulate matter in the air, and this is going to be optically because you just do not have many other choices.

Here is the problem, mathematically, from zero to 100 %, you must define 100 % as zero. Totaslly clean air is the setpoint, the zero, the reference. If the nibers do not start there, it will be hard to use them. It's like the audio example before, you don't say 99.7 % NOT distortion, you say 0.3 % distortion. Kinda flipped over. This is exactly the same in this case.

Take a calibrated light source. Then a detector. Whatever drop there is from the light source to the detector is the result.

Unless you use reflection, like in an optical smoke detector. Then 0%
is the baseline. He could probably count individual particles.
Click to expand...

Yup. Dark field light scattering is the easy way to do it, if you don't
need to go much below 0.5 microns. That's really simple--two air tubes,
a simple vacuum pump, a laser diode, a lens, a collecting mirror, and a
photodiode/TIA.

If the OP doesn't need size information, a condensation nucleus counter
is the way to go. Those draw the air sample into a supersaturated butyl
alcohol vapour, so any particles nucleate droplets.

Interestingly, the droplet radius grows linearly with time, so even a
really really small particle (10 nm or so) produces just about the same
size droplet as a 1-um particle.

Cheers

Phil "former crud guy" Hobbs




--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:

You want to detect particulate matter in the air, and this
is going to be optically because you just do not have many other choices.
Click to expand...

It's called a nephelmometer and uses light scattering. I have a
Nikken #1394 Air Quality Monitor:
<http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg>
I don't think this model is sold any more. The photo is me using it
to find the source of the burning smell in the office. It turned out
to be an overheated resistor inside the UPS in the photo. The unit is
quite sensitive. I can stamp my feet on the rug and cause the graph
to almost go full scale from the dust. Same with a couch or chair.
You could probably clone the function quite easily.

More:
<http://www.nwcg.gov/pms/pubs/SMG/177-186.pdf>
<http://en.wikipedia.org/wiki/Nephelometer>
Overkill:
<http://www.esrl.noaa.gov/gmd/aero/instrumentation/neph_desc.html>


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
On Mon, 30 Jun 2014 15:43:30 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

Den tirsdag den 1. juli 2014 00.27.52 UTC+2 skrev Robert Macy:
On Mon, 30 Jun 2014 15:08:14 -0700, Jim Thompson

To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:



On Mon, 30 Jun 2014 14:22:00 -0700, RobertMacy

robert.a.macy@gmail.com> wrote:



On Mon, 30 Jun 2014 13:43:17 -0700, John Larkin

jlarkin@highlandtechnology.com> wrote:



...snip...



Cars aren't bad. Diesels, in busses, trucks, and construction/farm

machinery, are.



I'm a bit skeptical about the evils of CO2, but particulates are nasty

for people and the planet.



Particulates melt snow, which is especially evil.



Cars aren't bad. What about thousands of brake linings turning to

powedery

dust at a Stop sign ??



Depends on whether the dust falls to the ground or is fine enough to

become airborne.



...Jim Thompson



From the way that stuff migrates all over the wheels on my car, I'd say

it's pretty 'airborne'



Remember when the linings were made of asbestos? Which subsequently have

been removed from the market. Coincidentally? after reports finding high

levels in lungs of people who live near stop signs vs middle of the

blocks, more open areas.

it the particle size that's important, if they are big enough it is is just
dirt it is when they are small enough to get deep into the lungs and stay there is gets dangerous, like asbestos and according to some exhaust from modern high pressure diesels and gasoline direct injection
Click to expand...

Yes, particle size is key. Over 10um, the danger isn't so high. The
respiratory system tends to clean this stuff out before it gets the
lungs. At 2.5um the particles are a perfect size to get into the
lungs and stay there. At some point, though, particulates will pass
through the alveoli walls, into the blood stream (where they may be
toxic or simply cleared from the system).

When I look for dust management for woodworking, I make sure the
filters will filter 1um particles (about the best that can be found).
Wood isn't generally toxic (though some species certainly are),
though, so 1um is likely good enough.
 
Jeff Liebermann <jeffl@cruzio.com> wrote:

On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:

You want to detect particulate matter in the air, and this is going
to be optically because you just do not have many other choices.

It's called a nephelmometer and uses light scattering. I have a
Nikken #1394 Air Quality Monitor:
http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg
I don't think this model is sold any more. The photo is me using it
to find the source of the burning smell in the office. It turned out
to be an overheated resistor inside the UPS in the photo. The unit is
quite sensitive. I can stamp my feet on the rug and cause the graph
to almost go full scale from the dust. Same with a couch or chair.
You could probably clone the function quite easily.
Click to expand...

I could not find a user manual for your Nikken. If you have a pdf and can
spare the time, could you upload it to your web site?

This is a very interesting way to use a particle counter. I have some
questions:

How does the Nikken operate?

Is there a table showing the particle concentration vs size?

What type of resistor was it?

Why did the resistor give off particles?

Was it hot enough to give off smoke?

Could you detect the source by smell?

I use the Dylos DC1100 PRO, which is a laser particle counter. It shows
the particle count for two size ranges of particles: 0.5 micron to 2.5
microns, and greater than 2.5 microns. I believe it discriminates between
particle sizes by measuring the width of the pulse as a particle passes
through the light gap.

http://www.dylosproducts.com/ornodcproair.html

I have two units and I am always amazed at how well the readings agree
between them.

I wonder how the Dylos and Nikken would compare in ability to
discriminate between different size particles. Does the Nikken have more
size ranges?
 
>"(I think dropbox got upset when I wouldn't sign up) "

The OP fucked up. he did not put it in his "public" directory. If you don't put it in "public", nobody can get to it but you, or anyone on YOUR account.
 
"Unless you use reflection, like in an optical smoke detector. Then 0%
is the baseline. He could probably count individual particles"
Click to expand...

That may solve a problem but it creates another.

Then the mirror has to be cleaned.

Now if this thing is allowed to have moving parts we can deal with that. In fact even a lens would have to be cleaned sooner or later but a mirror would of course be worse. Emitting surface, detecting surface and then reflecting surface. Bad enough without that reflector.

But then, that is all up to the designer. Maybe it would be better. We are still a bit scant on details until - well - whatever.
 
On 6/30/2014 8:24 PM, Steve Wilson wrote:
Jeff Liebermann <jeffl@cruzio.com> wrote:

On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:

You want to detect particulate matter in the air, and this is going
to be optically because you just do not have many other choices.

It's called a nephelmometer and uses light scattering. I have a
Nikken #1394 Air Quality Monitor:
http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg
I don't think this model is sold any more. The photo is me using it
to find the source of the burning smell in the office. It turned out
to be an overheated resistor inside the UPS in the photo. The unit is
quite sensitive. I can stamp my feet on the rug and cause the graph
to almost go full scale from the dust. Same with a couch or chair.
You could probably clone the function quite easily.

I could not find a user manual for your Nikken. If you have a pdf and can
spare the time, could you upload it to your web site?

This is a very interesting way to use a particle counter. I have some
questions:

How does the Nikken operate?

Is there a table showing the particle concentration vs size?

What type of resistor was it?

Why did the resistor give off particles?

Was it hot enough to give off smoke?

Could you detect the source by smell?

I use the Dylos DC1100 PRO, which is a laser particle counter. It shows
the particle count for two size ranges of particles: 0.5 micron to 2.5
microns, and greater than 2.5 microns. I believe it discriminates between
particle sizes by measuring the width of the pulse as a particle passes
through the light gap.

http://www.dylosproducts.com/ornodcproair.html

I have two units and I am always amazed at how well the readings agree
between them.

I wonder how the Dylos and Nikken would compare in ability to
discriminate between different size particles. Does the Nikken have more
size ranges?
Click to expand...

AFAIK size measurement is always done by thresholding the pulse heights.
The scattered light power goes as the sixth power of the particle
radius. (I've recently reverse-engineered several such units for two
court cases, and they all worked that way.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top