I need a simple pollen particle counter.

Discussion in 'Electronic Design' started by mike, Feb 8, 2012.

  1. mike

    mike Guest

    I'm looking for cheap/simple way to measure relative airborne particle
    counts for pollen-sized particles.
    The objective is to get some feel for how well various furnace
    filters work at filtering allergens.

    Don't need any fancy features or accuracy, just general relative numbers.

    REAL particle counters seem to work by shining a laser thru a cell
    and measuring light reflected from the particles.
    I did some experiments shining a laser pointer thru the air stream.
    I could see the occasional flash, but it's going to take a lot
    more optics and sensitive detectors than I'm willing to invest in to get
    anything useful.

    Cheapest particle counter I found was over $200, so that ain't
    gonna happen.

    Thought about charging the suspended particles and measuring
    current in a collection plate. Simple concept, but I expect the
    SNR is gonna be very low and the implementation not so simple.

    My itchy eyes work well, but the time constant is LONG and the
    uncontrollable experimental variables make it difficult to draw any
    conclusions.

    I'm looking for a clever idea to get some "feel" for how well
    a particular filter configuration removes pollen from the air
    without waiting for my eyes to get swollen shut.

    Ideas?
    Thanks, mike
     
    mike, Feb 8, 2012
    #1
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  2. mike

    mike Guest

    On 2/7/2012 9:55 PM, Dennis wrote:
    > "mike"<> wrote in message
    > news:jgsqsp$l3t$...
    >> I'm looking for cheap/simple way to measure relative airborne particle
    >> counts for pollen-sized particles.
    >> The objective is to get some feel for how well various furnace
    >> filters work at filtering allergens.
    >>
    >> Don't need any fancy features or accuracy, just general relative numbers.
    >>
    >> REAL particle counters seem to work by shining a laser thru a cell
    >> and measuring light reflected from the particles.
    >> I did some experiments shining a laser pointer thru the air stream.
    >> I could see the occasional flash, but it's going to take a lot
    >> more optics and sensitive detectors than I'm willing to invest in to get
    >> anything useful.
    >>
    >> Cheapest particle counter I found was over $200, so that ain't
    >> gonna happen.
    >>
    >> Thought about charging the suspended particles and measuring
    >> current in a collection plate. Simple concept, but I expect the
    >> SNR is gonna be very low and the implementation not so simple.
    >>
    >> My itchy eyes work well, but the time constant is LONG and the
    >> uncontrollable experimental variables make it difficult to draw any
    >> conclusions.
    >>
    >> I'm looking for a clever idea to get some "feel" for how well
    >> a particular filter configuration removes pollen from the air
    >> without waiting for my eyes to get swollen shut.
    >>
    >> Ideas?
    >> Thanks, mike

    >
    >
    > Would these things work?
    >
    > http://sharp-world.com/products/device/lineup/data/pdf/datasheet/gp2y1010au_e.pdf
    > http://sensorapp.net/?p=479
    >
    >

    Nice find.
    I can't figure out if it would be useful for what I want.

    I found a few papers on allergen concentrations, but don't understand.
    They talk about densities in kg/l in one paragraph, then dilution
    ratios in l/l. I haven't found enough consistent numbers to translate into
    the mg/l of the sensor sensitivity spec.

    Articles related to application of the sensor show it detecting visible
    smoke from burning material. That's way more dense than what I
    anticipate measuring.

    I may have to buy one and just test it.
    Thanks, mike
     
    mike, Feb 8, 2012
    #2
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  3. mike

    Oppie Guest

    "Dennis" <> wrote in message
    news:...
    >
    > This link below almost gets me excited:
    >
    > http://circuitcellar.com/contests/designstellaris2010/winners/TI2822.html


    Interesting - didn't know about the fluorescence aspect of pollen detection.
    I had been thinking more along the lines of the old school smoke detectors
    (circa 1960) that used a right angle light/sensor arrangement to detect
    dispersed light from particles that entered a black box.
    Oppie
     
    Oppie, Feb 8, 2012
    #3
  4. mike

    Oppie Guest

    Oppie, Feb 8, 2012
    #4
  5. mike

    mike Guest

    On 2/8/2012 4:05 AM, Dennis wrote:
    > "mike"<> wrote in message
    > news:jgtl68$vas$...
    >> On 2/7/2012 9:55 PM, Dennis wrote:
    >>> "mike"<> wrote in message
    >>> news:jgsqsp$l3t$...
    >>>> I'm looking for cheap/simple way to measure relative airborne particle
    >>>> counts for pollen-sized particles.
    >>>> The objective is to get some feel for how well various furnace
    >>>> filters work at filtering allergens.
    >>>>
    >>>> Don't need any fancy features or accuracy, just general relative
    >>>> numbers.
    >>>>
    >>>> REAL particle counters seem to work by shining a laser thru a cell
    >>>> and measuring light reflected from the particles.
    >>>> I did some experiments shining a laser pointer thru the air stream.
    >>>> I could see the occasional flash, but it's going to take a lot
    >>>> more optics and sensitive detectors than I'm willing to invest in to get
    >>>> anything useful.
    >>>>
    >>>> Cheapest particle counter I found was over $200, so that ain't
    >>>> gonna happen.
    >>>>
    >>>> Thought about charging the suspended particles and measuring
    >>>> current in a collection plate. Simple concept, but I expect the
    >>>> SNR is gonna be very low and the implementation not so simple.
    >>>>
    >>>> My itchy eyes work well, but the time constant is LONG and the
    >>>> uncontrollable experimental variables make it difficult to draw any
    >>>> conclusions.
    >>>>
    >>>> I'm looking for a clever idea to get some "feel" for how well
    >>>> a particular filter configuration removes pollen from the air
    >>>> without waiting for my eyes to get swollen shut.
    >>>>
    >>>> Ideas?
    >>>> Thanks, mike
    >>>
    >>>
    >>> Would these things work?
    >>>
    >>> http://sharp-world.com/products/device/lineup/data/pdf/datasheet/gp2y1010au_e.pdf
    >>> http://sensorapp.net/?p=479
    >>>
    >>>

    >> Nice find.
    >> I can't figure out if it would be useful for what I want.
    >>
    >> I found a few papers on allergen concentrations, but don't understand.
    >> They talk about densities in kg/l in one paragraph, then dilution
    >> ratios in l/l. I haven't found enough consistent numbers to translate
    >> into
    >> the mg/l of the sensor sensitivity spec.
    >>
    >> Articles related to application of the sensor show it detecting visible
    >> smoke from burning material. That's way more dense than what I
    >> anticipate measuring.
    >>
    >> I may have to buy one and just test it.
    >> Thanks, mike
    >>
    >>

    >
    >
    > This link below almost gets me excited:
    >
    > http://circuitcellar.com/contests/designstellaris2010/winners/TI2822.html
    >
    >

    Me too.
    It has some nice features.
    It discriminates and counts only the biologic elements.
    The excitation frequency is different from the detection frequency,
    so optical filtering should be able to significantly increase SNR.

    The closest thing I found to performance data was, "it's not very
    sensitive."
    Wish I knew what that meant.
    To be useful, a device has to be able to discriminate pollen levels
    around the threshold of hay fever symptoms.

    I'm coming to the conclusion that it's easier to build a high voltage
    supply than even a crude pollen detector. Might as well just build
    an electronic air filter and be done with it.
     
    mike, Feb 8, 2012
    #5
  6. mike

    Oppie Guest

    "mike" <> wrote in message
    news:jgum1l$2kd$...
    > On 2/8/2012 4:05 AM, Dennis wrote:
    >> "mike"<> wrote in message
    >> news:jgtl68$vas$...
    >>> On 2/7/2012 9:55 PM, Dennis wrote:
    >>>> "mike"<> wrote in message
    >>>> news:jgsqsp$l3t$...
    >>>>> I'm looking for cheap/simple way to measure relative airborne particle
    >>>>> counts for pollen-sized particles.
    >>>>> The objective is to get some feel for how well various furnace
    >>>>> filters work at filtering allergens.
    >>>>>
    >>>>> Don't need any fancy features or accuracy, just general relative
    >>>>> numbers.
    >>>>>
    >>>>> REAL particle counters seem to work by shining a laser thru a cell
    >>>>> and measuring light reflected from the particles.
    >>>>> I did some experiments shining a laser pointer thru the air stream.
    >>>>> I could see the occasional flash, but it's going to take a lot
    >>>>> more optics and sensitive detectors than I'm willing to invest in to
    >>>>> get
    >>>>> anything useful.
    >>>>>
    >>>>> Cheapest particle counter I found was over $200, so that ain't
    >>>>> gonna happen.
    >>>>>
    >>>>> Thought about charging the suspended particles and measuring
    >>>>> current in a collection plate. Simple concept, but I expect the
    >>>>> SNR is gonna be very low and the implementation not so simple.
    >>>>>
    >>>>> My itchy eyes work well, but the time constant is LONG and the
    >>>>> uncontrollable experimental variables make it difficult to draw any
    >>>>> conclusions.
    >>>>>
    >>>>> I'm looking for a clever idea to get some "feel" for how well
    >>>>> a particular filter configuration removes pollen from the air
    >>>>> without waiting for my eyes to get swollen shut.
    >>>>>
    >>>>> Ideas?
    >>>>> Thanks, mike
    >>>>
    >>>>
    >>>> Would these things work?
    >>>>
    >>>> http://sharp-world.com/products/device/lineup/data/pdf/datasheet/gp2y1010au_e.pdf
    >>>> http://sensorapp.net/?p=479
    >>>>
    >>>>
    >>> Nice find.
    >>> I can't figure out if it would be useful for what I want.
    >>>
    >>> I found a few papers on allergen concentrations, but don't understand.
    >>> They talk about densities in kg/l in one paragraph, then dilution
    >>> ratios in l/l. I haven't found enough consistent numbers to translate
    >>> into
    >>> the mg/l of the sensor sensitivity spec.
    >>>
    >>> Articles related to application of the sensor show it detecting visible
    >>> smoke from burning material. That's way more dense than what I
    >>> anticipate measuring.
    >>>
    >>> I may have to buy one and just test it.
    >>> Thanks, mike
    >>>
    >>>

    >>
    >>
    >> This link below almost gets me excited:
    >>
    >> http://circuitcellar.com/contests/designstellaris2010/winners/TI2822.html
    >>
    >>

    > Me too.
    > It has some nice features.
    > It discriminates and counts only the biologic elements.
    > The excitation frequency is different from the detection frequency,
    > so optical filtering should be able to significantly increase SNR.
    >
    > The closest thing I found to performance data was, "it's not very
    > sensitive."
    > Wish I knew what that meant.
    > To be useful, a device has to be able to discriminate pollen levels
    > around the threshold of hay fever symptoms.
    >
    > I'm coming to the conclusion that it's easier to build a high voltage
    > supply than even a crude pollen detector. Might as well just build
    > an electronic air filter and be done with it.
    >


    Since the design was based on Fluorescence of the pollen grains, sensitivity
    might be increased by either changing the excitation wavelength (the LED) or
    the bandpass and center wavelength of the emission detector. Do a search for
    "emission spectra of pollen" or the like and see what comes up.
     
    Oppie, Feb 8, 2012
    #6
  7. mike

    Winston Guest

    Jon Elson wrote:
    > Oppie wrote:
    >
    >> "Dennis"<> wrote in message
    >> news:...
    >>>
    >>> This link below almost gets me excited:
    >>>
    >>> http://circuitcellar.com/contests/designstellaris2010/winners/TI2822.html

    >>
    >> Interesting - didn't know about the fluorescence aspect of pollen
    >> detection. I had been thinking more along the lines of the old school
    >> smoke detectors (circa 1960) that used a right angle light/sensor
    >> arrangement to detect dispersed light from particles that entered a black
    >> box.
    >> Oppie

    > I used to work in air pollution research. A guy built an instrument
    > to do this. It used a big old laser tube, I think you could do this
    > with a diode laser now. It focused a laser down to a small spot using
    > an 8mm movie camera lens (gives you some idea when I was involved in this).
    > There was a chamber that had a mild vacuum pulling on it, and a piece of
    > hypodermic tubing allowing in a jet of the air sample. The end of the
    > hypo tubing was near and pointing right at the focal spot of the laser.
    > There was a photmultiplier tube looking at this region from 90 degrees.
    > You could pipe the PMT signal to a speaker and hear the clicks, which was
    > good for aligning the optics. This thing would pick up VERY small
    > particles, pollen grains would be a lot easier. If you don't mind running
    > the pump, this setup could be run continuously for weeks or months
    > to get seasonal data.


    That'd work much better with a linearly controlled
    laser diode than with a PWM - controlled laser diode. :)

    --Winston
     
    Winston, Feb 13, 2012
    #7
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