laser oil fluorescence proof of concept

[Jeffrey Warren]

I just worked with some smart and excitable kids from Parts & Crafts (partsandcrafts.org) and we managed to get a sample of suspected motor oil residue from a nearby street drain to fluoresce strongly enough to be detected (faintly) by a desktop spectrometry kit:

http://spectralworkbench.org/analyze/spectrum/7893

Exciting! See the red region just below 600 nanometers.

We did it by using one of the "psychedelic effects" caps for the green laser pointer, which makes crazy pattterns of laser light -- but importantly, it spread the beam of the laser out enough to create a lot more fluorescence. The signal is *very* faint, but definitely there. 

I just posted a research note too: http://publiclab.org/notes/warren/05-14-2013/laser-oil-fluorescence-proof-of-concept

Jeff

[Don Blair]

It's funny, Craig found a company that makes underwater probes for assessing crude oil which uses UV light and detects flourescence ... we got all excited about it, then thought -- wait, PLOTS has probably already figured out a DIY method for this ... this is really cool!

Btw:  how expensive are these awesome laser pointers, w/ what wattage?  Do you think that two or more laser pointers, each with these caps, pointed at the same sample, would increase the signal significantly?

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[Jeffrey Warren]

MOAR LASERS is definitely a good idea, ahem. I was also thinking if we had a small plastic mirror on the other side, we'd get 2x the amount of laser, roughly. 

These lasers are about $5 on Amazon, though not all come with the sweet psychedelic caps: http://www.amazon.com/s?ie=UTF8&keywords=green%20lasers&page=1&rh=i%3Aaps%2Ck%3Agreen%20lasers

[Don Blair]

[Sharks will be likely be useful for this project, too.  Not sure how, yet.]

Mirrors: brilliant, and cheaper than laserz!

Then I thought: it'd be neat to have a cylindrical, mirrored container into which to insert the vial, so that the light bounced off many times inside, enhancing chances of fluorescence (hopefully)

Then I thought: wait, these vials are like little cylinders ... maybe one can find cheap partially-reflective-coating cylinders, so that the laser light bounces around a lot more internally ...

Then I thought: maybe the vials could be have fully mirrored interiors (or just be glass, but covered in some tape / other material that allowed for reflection), but you just shine the light in from above; or find some cheapo fiber optic cable, dip it in the vial ...

Then I thought: aren't there toys with plasticy-bendy fiber optics? I wonder what would happen with one of those fibers dipped into the solution, laser on the other end ... and if there's some super cheap way of modding / smashing the fiber optic tip so that the outcoming light has more chances to scatter ...

Then I saved you all from further nonsense by hitting "Send".

[Jeff Hecht]

Fluorescence also depends on wavelength, so it would be interesting to try blue laser pointers. Two types are available, "purple" ones emitting at 405 nm (the wavelength of BluRay players) and true blue ones emitting around 450 nm (the wavelength of the blue LEDs in LED lamps and flashlights). Lots are available on the Internet, but many sellers do not clearly identify which color they have. They might produce stronger fluorescence, but they also might excite the mineral oil carrier, which would drown out the light from the pollutant. I should order a couple and see what they do.

- Jeff Hecht

On Tuesday, May 14, 2013 5:24:14 PM UTC-4, Jeffrey Warren wrote:

MOAR LASERS is definitely a good idea, ahem. I was also thinking if we had a small plastic mirror on the other side, we'd get 2x the amount of laser, roughly. 

These lasers are about $5 on Amazon, though not all come with the sweet psychedelic caps: http://www.amazon.com/s?ie=UTF8&keywords=green%20lasers&page=1&rh=i%3Aaps%2Ck%3Agreen%20lasers

On Tue, May 14, 2013 at 4:29 PM, Don Blair <dwb...@physics.umass.edu> wrote:

It's funny, Craig found a company that makes underwater probes for assessing crude oil which uses UV light and detects flourescence ... we got all excited about it, then thought -- wait, PLOTS has probably already figured out a DIY method for this ... this is really cool!

Btw:  how expensive are these awesome laser pointers, w/ what wattage?  Do you think that two or more laser pointers, each with these caps, pointed at the same sample, would increase the signal significantly?

On Tue, May 14, 2013 at 3:58 PM, Jeffrey Warren <je...@publiclab.org> wrote:

I just worked with some smart and excitable kids from Parts & Crafts (partsandcrafts.org) and we managed to get a sample of suspected motor oil residue from a nearby street drain to fluoresce strongly enough to be detected (faintly) by a desktop spectrometry kit:

http://spectralworkbench.org/analyze/spectrum/7893

Exciting! See the red region just below 600 nanometers.

We did it by using one of the "psychedelic effects" caps for the green laser pointer, which makes crazy pattterns of laser light -- but importantly, it spread the beam of the laser out enough to create a lot more fluorescence. The signal is *very* faint, but definitely there. 

I just posted a research note too: http://publiclab.org/notes/warren/05-14-2013/laser-oil-fluorescence-proof-of-concept

Jeff

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[Don Blair]

Great idea!

Semi-related note: Jeff (H): do you happen to have a lead on inexpensive lasers / LEDs that would emit strongly around 488 nm?  That's the wavelength useful for exciting green fluorescent protein in a biology experiment I'm playing around with, and it'd be great to find a nice DIY way to approach it ...

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[Jeff Hecht]

Don -
The green fluorescent protein was bioengineered to absorb at 488 nanometers, because argon gas lasers emit strongly at that wavelength. But argon gas lasers are expensive and inefficient, and now green LEDs and semiconductor diode lasers are available. The problem is that right now the wavelengths readily available from them are blue around 450 nm (LEDs and lasers) and deep violet (405 nm lasers, mass produced for BluRay players). So those wavelengths are the ones available cheaply.

One place that offers 488-nm diode lasers is WorldStar Tech in Canada - http://www.worldstartech.net/UV_Violet_blue_laser.htm  However, their data sheets do not list prices (not a good sign). Another is Shanghai Laser and Optics in China http://www.lasercentury.com/product.asp?id=493 but again they do not list prices. There's also Cobalt in Sweden http://www.cobolt.se/mld488nm.html , again, with no listed prices.

One alternative would be looking for other variations of the green fluorescent protein, some of which are listed at http://www.biotek.com/resources/articles/green-fluorescent-proteins.html

It may be worth buying a 405-nm violet laser pointer, which I've seen as cheap as $20 or so on the net, to see if green fluorescent protein absorbs enough light at that wavelength to produce useful fluorescence.

Hope that helps,
Jeff Hecht

On Wednesday, May 15, 2013 4:36:44 PM UTC-4, Don Blair wrote:

Great idea!

Semi-related note: Jeff (H): do you happen to have a lead on inexpensive lasers / LEDs that would emit strongly around 488 nm?  That's the wavelength useful for exciting green fluorescent protein in a biology experiment I'm playing around with, and it'd be great to find a nice DIY way to approach it ...

On Wed, May 15, 2013 at 9:23 AM, Jeff Hecht <hech...@gmail.com> wrote:

Fluorescence also depends on wavelength, so it would be interesting to try blue laser pointers. Two types are available, "purple" ones emitting at 405 nm (the wavelength of BluRay players) and true blue ones emitting around 450 nm (the wavelength of the blue LEDs in LED lamps and flashlights). Lots are available on the Internet, but many sellers do not clearly identify which color they have. They might produce stronger fluorescence, but they also might excite the mineral oil carrier, which would drown out the light from the pollutant. I should order a couple and see what they do.

- Jeff Hecht

On Tuesday, May 14, 2013 5:24:14 PM UTC-4, Jeffrey Warren wrote:

MOAR LASERS is definitely a good idea, ahem. I was also thinking if we had a small plastic mirror on the other side, we'd get 2x the amount of laser, roughly. 

These lasers are about $5 on Amazon, though not all come with the sweet psychedelic caps: http://www.amazon.com/s?ie=UTF8&keywords=green%20lasers&page=1&rh=i%3Aaps%2Ck%3Agreen%20lasers

On Tue, May 14, 2013 at 4:29 PM, Don Blair <dwb...@physics.umass.edu> wrote:

It's funny, Craig found a company that makes underwater probes for assessing crude oil which uses UV light and detects flourescence ... we got all excited about it, then thought -- wait, PLOTS has probably already figured out a DIY method for this ... this is really cool!

Btw:  how expensive are these awesome laser pointers, w/ what wattage?  Do you think that two or more laser pointers, each with these caps, pointed at the same sample, would increase the signal significantly?

On Tue, May 14, 2013 at 3:58 PM, Jeffrey Warren <je...@publiclab.org> wrote:

I just worked with some smart and excitable kids from Parts & Crafts (partsandcrafts.org) and we managed to get a sample of suspected motor oil residue from a nearby street drain to fluoresce strongly enough to be detected (faintly) by a desktop spectrometry kit:

http://spectralworkbench.org/analyze/spectrum/7893

Exciting! See the red region just below 600 nanometers.

We did it by using one of the "psychedelic effects" caps for the green laser pointer, which makes crazy pattterns of laser light -- but importantly, it spread the beam of the laser out enough to create a lot more fluorescence. The signal is *very* faint, but definitely there. 

I just posted a research note too: http://publiclab.org/notes/warren/05-14-2013/laser-oil-fluorescence-proof-of-concept

Jeff

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[Lasse Forsberg]

Hi

 

People interested in saltwater and corals often experiment with monochrome LED diods emitting wavelenghts between 380 - 470 nm. Therefore - there is a market for diods of specific wavelenghts in the blue aera. You can search for them on the internet but as stated before - you not really know what you will get.. However - there is some sellers at the aquarium DIY market that clearly identify the wavelenghts they sell. I´m not sure if it is allowed to mention specific sellers here but if you search for "EPILEDS 3W 402.5nm-405nm UV LED" you will found some information. (they also have other wavelenghts)

 

Sincerely Lasse Forsberg, Sweden

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[Tiberius Brastaviceanu]

You can buy high power LED on DIGIKEY 

You can coat glass and PMMA using a very simple method. This allows you to customize the shape of your mirror. I would go for a rectangular vial, to bounce the laser/LED inside for a lot of times. 

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[Jeff Hecht]

Did a little more checking and found (and bought) a 405-nm laser for $6.22 on eBay. At that price, it's worth buying one and seeing if it excites usable amounts of fluorescence. Virtually all the "blue" lasers on eBay are 405-nm emitters, which look violet or purple to the eye, and look very faint to some people's eyes (like mine). The 450-nm blue pointers are $50 and up, and some unpackaged lasers are on sale for a bit less.

Jeff H.

[Tiberius Brastaviceanu]

Why not a UV lamp? You don't need coherent light... 

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[Jeff Hecht]

A UV lamp should work, too; I thought of the laser first and found an unexpectedly cheap one. eBay also has UV flashlights which should work. The main advantage of the laser is that it concentrates the light in a tight beam, so the fluorescence would be concentrated in the beam and might be more intense and easier to spot. -- Jeff Hecht

[Jeffrey Warren]

I was wondering about UV bulbs - for ones based on mercury (CFLs with a dark coating), what wavelengths can we expect to see? I guess I also wonder for incandescent fluorescent bulbs and LEDs... is it low enough for most fluorescence use?

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[Jeff Hecht]

A "blacklight" lamp is a fluorescent lamp which emits ultraviolet around 370-375 nanometers. That's in the ultraviolet, invisible to the eye, which comes from a phosphor in the tube. Ultraviolet LEDs normally emit in about the same band, with the light coming directly from the LED, which is a variant on the blue LEDs used in solid-state lighting. That's enough to induce fluorescence in a lot of things - including many types of white paper. The 405-nm light from a 'blue' laser pointer also induces fluorescence in many things; leaves fluoresce red. Without fluorescence the laser spot is a deep purple, but most objects I've tested it with make it look pale blue or white. The yellow plastic on some highlighters glows a very bright yellow-green. The fluorescence winds up looking much brighter than the reflected laser light because the eye is relatively insensitive to 405 nm.

LED bulbs and incandescent should not generate much UV, but I don't have the equipment to test them. The mercury in fluorescent lamps emits much deeper in the ultraviolet, around 253 nanometers, which excites phosphors, but is blocked by the glass in the tube.

-- Jeff H

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