Although Eric de Kruijk struggles with needlestick fears, he puts the needle in the spotlight in his column. The design of this medical device has been – and still is – well thought out.
With rippling armpits and high pulse, I sit in the chair in front of her. As I nicely recite my date of birth, she sees my sweaty and pale face and asks if I’m okay. “Yes, it should probably go,” I say to her, but primarily to myself. I roll up my sleeve and as I look the other way, I notice that she puts the needle on the syringe filled with a vaccine into my upper arm. This time, too, the fear turns out to be greater than the pain itself.
In this section of Daily use of De Kruijk I dive into the design of the most commonly used medical device: the hypodermic needle. Every year, about 16 billion shots are taken worldwide by doctors and nurses alone. And after hundreds of years of use, better designs are still being considered every day.
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The first documented experiment with the hypodermic needle dates back to 1656, conducted by the scientist Sir Christopher Wren. Yes, those were the days when ‘scientist’ could still be used as an all-encompassing title. Wren was a Newtonian mathematician, astronomer, architect, surveyor and researcher in human anatomy. He discovered that liquids or medicines could be injected directly into the bloodstream with a hollow and sharp feather pen. He saw it as an interesting way to administer medication, but because the injection led to fatal infections in some, it was quickly abandoned.
Injection needles work perfectly and are also dirt cheap
Two centuries later, in 1850, French instrument maker Joseph Charrière patented his latest invention: the hollow metal injection needle. You could make it sterile by heating it, which prevented infections. Today, most injection needles are made of stainless steel. They are shaped into a shape and the tip is sharpened to a razor-sharp and oblique angle. Then they go sterile into their packaging. They work perfectly and are also dirt cheap.
When does the painless needle come?
But because the group of sensitive delicate souls – to which I belong – is quite large, the needle developers have begun to think further about how to make the dot more comfortable and painless. Contrary to what I expected, it does not seem to be the best solution to make the needle thinner. In 2006, dentists examined the pain experience in about a thousand patients using the thinnest to the thickest needle possible. While the sight of the thick needle could cause panic, blindfolded patients actually experienced no difference in pain.
However, there is a lot to gain if you reduce the resistance that a needle encounters in the skin. For example, many different needles are now made with a coating of polymers that serve as a lubricant. And the biomimicri lab at Ohio State University has been working hard in recent years on a needle inspired by the mosquito’s snout. After all, such an insect is able to sting you almost unnoticed and painlessly. The mosquito has a particularly complex puncture technique, but the researcher was able to mimic one part well. The tip of the sharp mosquito needle contains small, sharp saw teeth. The mosquito vibrates its needle at high frequency – like a kind of jigsaw – into the skin. Compare that to slicing a ripe tomato with a sharp smooth knife versus a sharp serrated knife. The latter is much smoother. And here too the following applies: less resistance means less pain.
The disadvantage of all innovations like this is that they come with a higher price tag and that the ‘normal’ needle, which costs almost nothing, works fine according to the health insurances. Little souls like me will probably have to be patient for a while before the painless needle is also included in the standard package of vaccine sticks. So for a possible next shot, I just gather all my courage … and a good deodorant.
This column is also in KIJK 5/2022.