h a l f b a k e r yNot so much a thought experiment as a single neuron misfire.
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I was marveling at the brightness of a mini Maglight recently. Pressed to the skin in a dark room, it is possible to transilluminate a small hand and see the bones.
This principle could be used to make a veinfinding device. It assumes that there exist very very bright lights which are not so hot
as to burn the skin. Venous blood absorbs light at a particular red wavelength. Transillumination of a hand or arm with bright red light of that wavelength should make the veins stand out, as they will absorb more light than the relatively bloodless areas of fat and muscle around them.
Then the needle goes in!
US patent 6,424,858
http://www.google.com/patents/US6424858
imaging apparatus for transillumination and visually exposing vasculature of the human anatomy by passing infrared light through it [xaviergisz, Mar 03 2005, last modified May 07 2016]
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If you shift the spectrum up a bit to, say, about 2nm and put an imager on the other side of the appendage you might have even better results. |
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Saw a clever device recently: It viewed a
patient's arm in infra-red, which
showed up the veins really well, and
then projected an image of the vein
pattern back onto the arm in visible
light so the doctor could see it. |
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I think blood is red because it reflects red, but your idea may work - I'll use the needle while you move the LED around a bit. |
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660 nm. penetrates 8-30 mm. of skin/fat.
830-950 nm. penetrates 30-40 mm.,into joints, tendons etc.
Cells transmit light at the intensity of one candle seen 2-5 km away.
Light ignites the cellular metabolism 98% through eyes, 2% skin. Research suggests looking outside into semi-shaded areas unobstructed by glass(es), min. half hr./day. |
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I haven't checked this recently but cells are a different colour when oxidized and therefore a tumour can show up on scans because of lack of oxygen getting to cells.
Research is being done to pulse infra-red and other wavelengths of LED light into tumours/other for cell repair. Also the theory is that blood communicates with itself at a specific wavelength and pulsed frequency. Thus [Ling], blood is the colour that it communicates in. |
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Moreover I suggest the public be cautious of their close exposure to unresearched light sources/pulsed frequencies for health concerns. |
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Baked. Can't be bothered to find a link. It just is, okay? |
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A mate of mine at university worked on a robot that located veins and then did the stabbing bit, too. Can't remeber the details but it worked pretty good. |
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[bris] - why shift the spectrum that tiny amount? |
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[mens] - would penetration not also be affected by brightness? For example, sunlight penetrates the ocean differently at different wavelengths, but everything penetrates farther on a bright sunny day as compared to a cloudy day. I don't know about blood communicating with itself. That is pretty trippy. |
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[moom] - you gotta find the link. |
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I'll search more but from the same page of my old notes I see an LED intensity of 6-8000 millicandle mentioned, equals 55 milliwatts per LED with a 266 cycles per second pulse rate, compatable with body nervous system. |
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Midday summer sun is 100,000 lux. Typical indoor illumination is 1000 lux. |
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It's an absolute rather than a relative amount, [mens]. |
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Absolute and relative are two words I don't use so try again,[Bristolz]. I looked them up and words like that delay research for years, I'm postulating. |
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Sorry to not be clear. To shift 2nm would be a relative amount. To, instead, shorten the wavelength to 2nm, is an absolute amount and is what I intended. |
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Thank you Bristolz, I'm on a learning curve. |
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I love the 'bakery. Attending this anno series counts towards credit at Halfbaked University. Oh, and the cafeteria is serving tuna casserole on a bun tonight. |
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Blood, being the body's refrigerant, should be flowing in veins relatively cooler than their less vascular substrate. Temperature differences within a limb could either be directly visualized by infrared imaging or be enhanced for imaging by local application of heat such as used to make his vas deferens stand out during a vasectomy. |
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I just posted then deleted a very similar idea after receiving a nasty subcutaneous bruise from my friendly local phlebotomist. Wish this were more widely known, thanks, [bungston]. |
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The blood in veins should be not only less red
than the blood in arteries, but less red than the
blood in capillaries, since it's less oxygenated than
both. In fact, veins should be about the bluest
thing in their vicinity. I wonder if that's why they
look blue, despite the the dull, dark red shade of
venous blood when it fills an evacuated vial.
Pulse oximetry distinguishes oxygenated from
unoxygenated blood by absorbtion wavelength, so
the same trick ought to be possible in reverse.
However, arterial flow is pulsatile, which makes
discriminating signal from noise much easier than
in the venous case. |
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Anyway, there's already a mature technology for
bedside imaging of veins, and that's ultrasound. |
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The baked form of this idea (yes, it exists, no, I'm not
going to provide a link either, because I can't remember
what it's called, but every major hospital has one
collecting dust in a closet) isn't actually used to find veins
for flobotomy, nor does it need to be; if you've drawn
blood enough times, you can literally do it with your eyes
closed (of course, professional flobotomists _never_ do
this, for legal purposes). |
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