The wrath of snack sausages
They Shoot Porn Stars, Don't They?
Researchers have developed a microneedle inspired by the the blood-sucking action of a female mosquito. Described as "painless," the microneedle has applications for blood drawing, injections, and biomonitoring. Designed by engineers at the Indian Institute of Technology and Tokai University, the device uses shape-memory alloy to push the needle into the body. Then, a microelectromechnical pump sucks out the blood or delivers the drugs. From New Scientist:
Contrary to popular belief, a mosquito bite does not hurt. It is the anticoagulant saliva that the creature injects to stop your blood clotting that causes inflammation and pain.Mosquito-inspired microneedle (New Scientist)
The new needle has an inner diameter of around 25 microns and an external diameter of 60 microns, which is about the same size as a mosquito's mouthpart. Its size and the fact that it works by suction, makes it painless. To compare, a conventional syringe needle has an outer diameter of around 900 microns.
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Existing small-bore needles are already problematic due to hemolysis, which can alter lab results. I could see this being used for drug delivery, but it could be a problem if you used it to check a potassium level.
But glucose would be OK, you think? That's the one they mention in the article.
Begin so thin, what are the odds of it breaking off in the skin?
Not in the medical field. I have no idea. I just wouldn't want half of a needle stuck in me.
I can't remember if glucose is affected by hemolysis. When the cells are smashed by squeezing through a little tube, it changes some aspects of the chemistry. My local lab only carries tiny needles, and I must have big blood cells, because my potassium always comes out way high.
"Now here's an interesting bit of business, 007."
"Very nice, R. But aren't Rolexes a bit, well..."
"See here. Remove the winding stem, you'll find a micro needle, small as a mosquito's proboscis. They won't even feel it penetrate. The watch itself is a nano-scale pump capable of delivering a dose to either incapacitate or kill. Just set the hands to 6 or midnight."
Forget needles, where's my hypospray?
http://io9.com/5025663/where-is-my-hypospray
#4 leave the toilet seat lid down at night
Those needles would be great for diabetics. I doubt you'd have much trouble with hemolysis, because the flow of blood is so slow. The diameter of the needle is no problem, because blood cells can fit through capillaries, which are just as small. The problem with hemolysis in larger needles come from trying to pack too many cells too quickly into a narrow needle, coming from a vein with relatively high pressure. The blood here comes from capillaries, with MUCH lower volume and pressure.
Of course, these needles wouldn't be a lot of use for much other than glucose, or VERY low dose meds, because the time it would take to fill a vial for a CBC would be ridiculously long at 5 microliters/sec.
For people who hate needles, a 24 gauge with a small shot of lidocaine from a 28 or 30 gauge ahead of time solves most problems. For people with true phobias, not much helps at all (except benzodiazapines, which make everything better, no matter what!).
Glucose solution wouldn't be harmed by injecting through a very small bore needle but it might take a while longer than usual. Probably not an issue for a glucose drip.
Your potassium levels come out high because the very small bore of the needle causes the flow through it to be very turbulent (because the small cross-sectional area requires very high fluid velocity to get reasonable flow rates) which creates shear which breaks up the blood cells releasing potassium (and hemoglobin, etc.) at higher concentration than is normally in the plasma.
>This volume is sufficient for measuring blood-sugar levels in diabetics using a glucose sensor that can be attached to the needle in a "wristwatch" design.
Now if only commercial glucose monitors gave accurate readings.
I heard about the anticoagulant that mosquitoes inject a while back, and decided to test, personally, whether or not they take it back with them if you allow the transaction to complete. They do.. but its hard to resist the urge to bat them away once you feel the 'sting'.. but if you let them complete the whole process they will take most of the welt-juice with them and you'll not get those hives or bumps. I'm not making this up, you can try it (at least the variety of mosquitoes in the midwest, can't speak for anywhere else)
I once stood still for 15 minutes near a buggy river and just let every mosquito come and do its thing on me for the duration.. the next day I had very few 'bites' and none of them were very painful. The bites that hurt, if recollection serves me, were from immature mosquitoes that struggled to plant through my hair, and thus stabbed repeatedly and very shallow in order to dig in. The big mommas were very quick, in and out, and none of those bites had pain or itched.
catch anything?
Not a thing!
Gattacas scanners just got a little closer...
a conventional syringe needle has an outer diameter of around 900 microns
So what's a "conventional" syringe needle? I've seen everything from 30 gauge (about the thickness of a hair) to an 18 gauge. (about the thickness of a #2 pencil lead)
It hurts when a mosquito "bites" me such that I usually slap them before they can inject the anticoagulant. Maybe I am more sensitive than most though...