3D Printed Animal Stinger Needles Might Make Human Injections Less Painful

Most people don't enjoy the prick of a needle during shots, but a new bio-inspired microneedle — 3D printed with protruding barbs inspired by stinging creatures of nature — might make shots less painful, according to a paper published in Advanced Functional Materials.

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3D-printed microneedles with protruding bars less painful

Naturally, "protruding barbs" is not an inviting description. But they only stick out 0.05 centimeters (0.02 inches) from the needle's main body — roughly the same thickness of a pinky nail. According to the paper, the "bioinspired backward-facing curved barbs" were developed to enhance "tissue adhesion" to lessen pain typically associated with administering medication via syringe.

The 3D-printed needle was fashioned after nature, as researchers felt inspired by examples from the animal kingdom. Specifically, they looked to ones that could minimize pain yet maximize injection efficiency. They considered "microhooks of parasites, barbed stingers of honeybees, [and the] quills of porcupines" to invent their unique and functional barbed needle design.

One of the paper authors — Howon Lee — said the team's idea aimed to "mimic the way nature does things" to create something efficient and practically painless. Once the prototype was tested on raw chicken, Lee and his team surmised that the best design was one with six microneedles — each one with skin-gripping barbs.

Keeping needles solid with UV light

The new primal class of microneedles raises a lot of questions, but one reason it's so promising is that the researchers used a special solution mixed from a chemical and a polymer — the former is light absorptive — to synthesize them.

The ability to absorb light was crucial because it allows for the printed needle to get hard and strong when exposed to ultraviolet (UV) light. The barbs were also made for stiffness, but were printed thicker with more layers that interfered with solidification and made them too soft.

When the barbs are exposed to UV light, they shift shape from straight to horizontal protrusions along the needle into downward curving protrusions. If 3D printed needles fashioned after animal stingers sounds like science fiction, it probably means science is moving faster now more than ever, as scientists work to improve the human condition via the ongoing study of nature.

H/T Popular Mechanics