h a l f b a k e r yExpensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.
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So, labs, like mine, use pipette fillers. These are
basically trigger-operated air pumps used to fill/empty
the attached
pipettes. See link. Now, these normally have
NiCd/NiMH
batteries inside which need charging periodically. This
is
annoying all the time, but especially so when the
unit is
to
be used in a sterile cell-culture laminar-flow hood
(because
you have to have a charger in the hood). Cell culture
hoods are always brightly lit, but overnight they're
subject
to a sound thrashing six-of-the-best-trousers-down UV-
style, or in English, we turn on a short-wavelength UV
lamp, to sterilize the thing. So if a pipette-filler were to
be fitted with a UV-optimized solar panel, it would get
charged over night, also you could lose the charger,
which
are cheap plastic wall warts which do not stand up to
frequent UV-ing. Now, while you're at it, why not put the
solar panel INSIDE the pipette? no annoying bug-
harboring
seams and such.... you could do this by making the
whole
thing out of nicely UV-transparent plastic (see second
link).
This would render the inside of the pipette nice and
sterile
also. You'd have to optimize the internal components so
they didn't crumble in a week or two, but that's easy.
So, a completely transparent pipette, with a solar-panel
in
it. No hole for the charger socket any more (another
place
for bugs to hide). No charger (you free up space and a
wall
socket inside the cell-culture hood). More sterile. Looks
cooler. What's not to like?
Right, I've got cell culture to go and do.....
Pipette fillers
http://www.integra-...petboy_acu_1_e.html
[bs0u0155, Apr 17 2012]
UV-Transparent plastic
http://www.brand.de.../UV_Kuevette_EN.pdf
[bs0u0155, Apr 17 2012]
Quantum Dot Solar panels
http://en.wikipedia...ntum_dot_solar_cell
[bs0u0155, Apr 19 2012]
[link]
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//What's not to like ?// well... you're tying yourself to one manufacturer, and with a product composed of two sections, each with different mtbf's. |
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//pipette fillers// geez you kids got it easy these days: we had to use rubber bulbs. |
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//Cell culture hoods are always brightly lit//, so use an ordinary solar panel, and ditch the batteries altogether. |
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You mean I can use rubber bulbs?! No more spitting out 12-
3-5 solution because I overfilled my pipette? I've gotta get
some newer equipment for my lab*. |
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spider: they get used pretty heavily for a few hours
a day. I think the area available would only provide
enough power for charging. You've got about 40
square centimeters to play with. In use, more than
half of that will be covered by a hand, the other half
is not guaranteed to be pointing in an optimal
direction. I think charging is the way. However,
supercapacitors are getting cheaper and better. A
possible alternative there. |
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"well... you're tying yourself to one manufacturer,
and with a product composed of two sections, each
with different mtbf's" |
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er.... it's exactly the same component count as a
normal pipette filler... it has a solar panel, but no
power socket. I'll bet that power sockets+grad
students are less reliable than solar panels. Power
sockets are always breaking.
as for tying yourself to one manufacturer? er...? |
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Fair enough. I guess the part that isn't shaded by the hand is mostly occupied with the display; it's a while since I've used one. |
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Do you know how much power they use? You could estimate from how long it takes to run down a new set of batteries of known capacity. Or just measure the current directly. |
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Cover the existing wall wart with aluminum foil. That will protect it from UV. |
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Yes, but it'll also protect any microbes on it from UV. |
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//it's exactly the same component count as a normal pipette filler.// .... no, I mean you've got a pipette which lasts basically forever, and a solar panel which isn't going to last 5 years under heavy UV, and you know solar panel output isn't going to be compatible between filler manufacturers... ditto the batteries (thanks [sm]) |
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////pipette fillers// geez you kids got it easy these
days: we had to use rubber bulbs// Oh for goodness'
sake. Mouth pipette like a man. |
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As to the idea, what's not to like indeed? I'm not
actually sure that you'd get enough charge overnight
to last all day, though. The UV tubes are maybe 20-
50W? And your solar panel is going to be maybe 2"x1"
? Still, it might work. |
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// Mouth pipette like a man. // |
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Thank you. An occasional mouthful of concentrated
homebrew fertilizer is a small price to pay for scientific
dedication to indoor horticultural excellence on a slim
budget. |
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On the other hand, my light banks would charge one of
these suckers in a split second, so they would work well in
my application. If I ever find one in a Chemistry
Department dumpster (my usual source for lab equipment),
I'll definitely use it. |
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Why not coat the inside of the entire fume hood
with solar panels then run the UV lights off the solar
panels? Hang on a sec... logic circuit overload... back
in a minute. |
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So the UV bulbs we have are 50W, the standard
fluorescent lights are 32W x 2. and they're lit 24/7
by one light or the other. My feeling is that the
pipette fillers have a half life of about 5 years
anyway, before the seals start to fail. They're
normally powered entirely by a 8.4V 140mAh pp3
battery. This will last about 3-4 days heavy use,
but the batteries noticeably deteriorate so that
most work for about 1 day without the charger.
There's no display. |
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As for the solar panel failing, surely the 50W UV
bulbs aren't going to visit quite so much
destruction as the unshielded nuclear fusion
reactor that solar panels normally face. |
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As for panel size, the flat space on the side of our
models could easily accommodate 4"x1 on the top
and another 4"x1" on the handle. |
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So the average power is about .012W. Assuming the fluoros distribute their light over a 4' by 4' area at the distance of the pipette, a 4" by 1" panel gives a minimum system efficiency margin of ((8.4*0.14)/(24*4))/(4'/48' * 64) = 0.11025. Raw thermoydynamic efficiency could easily account for all of that, which rules out my 'no battery' scenario - although you might get by with a slightly larger panel and a modest supercapacitor. |
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I think most systems that use sunlight - including plants and solar panels - cope with UV by absorbing or reflecting it, not by using it. Is there even such a thing as a UV optimised solar panel? You could use a fluorescent coating to make one, of course. In theory, its reduced efficiency would neatly balance the efficiency loss due to fluorescence in the visible lights, so the calculations should vaguely match those above; which suggests that it could just barely recharge overnight with 8 square inches of panel. |
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Assuming the batteries don't develop a "memory"
through repeated incomplete charge/discharge
cycles, reducing their efficiency. |
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UV optimized? of course. You find the absorption
maximum (maxima?) of the solar panel in question.
Buy a bunch of Quantum Dots (or the generic
equivalent) that are tuned to emit at that
frequency range, pepper your solar panel with
them and BOOM... your UV is absorbed and re-
emitted at the appropriate frequencies. |
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Remember, if there is a net loss over the week.
The weekend might be enough to replenish the
deficit by Monday. |
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Also, the memory effect? is that when
remembering
how bad old battery technology was gives you
chills? |
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Actually, Quantum Dot solar panels are baked.... see
link... bugger. |
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