Although Eric de Kruijk struggles with needlestick fear, he puts the hypodermic needle in the spotlight in his column. The design of this medical device has been – and still is – well thought out.
With sloshing armpits and a high heart rate, I sit in the chair in front of her. As I neatly recite my date of birth, she sees my sweaty and pale face, and asks if I’m okay. “Yeah, it’ll be fine”, I say to her, but mainly to myself. I roll up my sleeve and as I look the other way, I feel her insert the needle of the syringe filled with a vaccine into my upper arm. This time, too, the fear turns out to be greater than the actual pain.
In this episode of Daily use by De Kruijk I dive into the design of the most commonly used medical device: the hypodermic needle. Every year, around 16 billion shots are taken worldwide by doctors and nurses alone. And after hundreds of years of use, better design is still considered every day.
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The first documented experiment with the hypodermic needle dates back to 1656, conducted by 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 of human anatomy. He discovered that you could directly inject liquids or medicines into the blood with a hollow and sharp quill pen. He saw it as an interesting way to administer drugs, 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, the French instrument maker Joseph Charrière patented his latest invention: the hollow metal hypodermic needle. You could make it sterile by heating it, which prevented infections. Today, most hypodermic needles are made of stainless steel. They are formed in a mold and the tip is sharpened to a razor-sharp and oblique angle. Then they go into their packaging sterile. They work perfectly and are also dirt cheap.
When will the painless needle arrive?
But because the group of sensitive faint-hearted—which I belong to—is quite large, the needle developers have started to think further about how to make pricking more comfortable and painless. Contrary to what I expected, making the needle thinner does not appear to be the best solution. In 2006, dentists examined the pain experience of 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 much to be gained if you reduce the resistance encountered by a needle in the skin. For example, many different needles are now made with a coating of polymers that serves as a lubricant. And the Ohio State University biomimicri lab has been working hard in recent years on a hypodermic 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 imitate 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 it 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 only next to nothing, works fine according to health insurers. Tiny souls like me will probably have to be patient for a while before the painless needle is also included in the standard package of the 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.