Researchers from Canada’s McGill University have created an ultra-precise 3D-printing nozzle derived from a mosquito’s proboscis. Scientific correspondent Nikolay Grinko has the details.
3D printing is a technology that appears poised to replace nearly all known material processing methods in the future. Sooner or later, engineers will master manipulating individual molecules, or even atoms, enabling the realization of the most ambitious and unconventional concepts. Of course, this milestone is still quite distant. Presently, such printers primarily operate via extrusion, where molten material is delivered to the working area through a fine nozzle and subsequently solidifies. Other methods exist (photopolymerization, laser cladding, etc.), but extrusion remains the leading technique. A distinct category is occupied by bioprinters, which handle living cells to fabricate organs or their components (albeit very small ones for now).
A team of academics at McGill University in Canada set out to develop extremely fine and inexpensive nozzles for bioprinting that would be both wear-resistant and biodegradable. Current models are manufactured from metal and plastic, failing to satisfy all criteria on this list. The decision was made to seek inspiration from natural materials. Our planet’s living organisms feature a multitude of tubular structures: examples include the internal vessels of plants, the stingers of various insects, snake fangs, and the proboscises of blood-sucking insects.
A mosquito’s proboscis is essentially just a protective sheath for six needles concealed within. Two needles, positioned at the sides, possess particularly sharp, serrated edges, which the mosquito uses to “saw” through the skin. Two other needles are used by the insect to part and brace the skin. However, the most intriguing are the remaining two. Through one of these, the mosquito injects a specialized blood-thinning substance beneath the skin to prevent clotting (this substance is what causes the subsequent itching and swelling at the bite site). The second needle is employed for locating blood vessels and, indeed, for drawing blood.
If all this intricate “machinery” is removed from the proboscis, one is left with a hollow tube perfectly suitable for ultra-precise 3D printing. Its internal diameter measures 20 micrometers, making it roughly half the thickness of the finest commercially available tips. The rigid, nearly straight form of the proboscis is ideal for stable printing, and its walls are robust enough to withstand internal pressures of about 60 kilopascals—a pressure comparable to what plastics handle. Thick bio-inks can be successfully delivered through this “mosquito nozzle.”
The team validated their innovation by constructing a specialized 3D printer they dubbed the “necroprinter.” The specialists secured a mosquito proboscis into a standard dispensing tip and utilized it to deposit specialized bio-ink. They subsequently succeeded in printing bio-scaffolds, used to support cell growth, and microstructures featuring line widths as narrow as 20 micrometers (about twice the thickness of a human hair). The team’s next objective is to explore other natural micro-nozzles that offer enhanced durability or superior resolution.
It is noteworthy that the entire history of human invention is predicated on borrowing from nature. Our airplanes mimic birds, our submarines resemble whales, helicopters bring to mind dragonflies, and so on. At some point, engineers set aside the principles of biomechanics, but recently, they have been returning to them with increasing frequency. They are building ocean exploration robots shaped like jellyfish and sea anemones. They are designing quadcopters with bird-like feet for perching on branches and wires. And now, they have moved directly backward: much like primitive hunters fastening shark teeth to spears, they are hunting mosquitoes to harvest their proboscises for bioprinting. This, of course, is a slight artistic embellishment.
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