The proboscis of a mosquito (seen in a scanning electron microscope image of one insect’s head) is used for piercing skin. It’s also perfect for precision 3-D printing.
DENNIS KUNKEL MICROSCOPY/Science Source
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A mosquito’s proboscis — the long, thin bit that pierces the skin — makes an excellent nozzle for fine 3-D printing. The proboscis’ unique geometry and mechanics make it well-suited for the task, researchers report in the Nov. 21 Science Advances
The scientists call this “3-D necroprinting.” The term comes from necrobotics, a field that uses animal parts in high-tech machines — for example, spider legs repurposed into robotic grippers. Using a proboscis as a nozzle, mechanical engineer Changhong Cao and colleagues were able to print lines as fine as 20 micrometers, or about half the width of a fine human hair. This would allow them to print at an intricate scale.
Daniel Preston, a mechanical engineer at Rice University in Houston who was not part of the study, says that dispense tips can be expensive and hard to build. Using parts that nature has already created can help “democratize” 3-D printing, he says, “by lowering costs and removing barriers to entry.”
Cao’s team analyzed many biological parts found in nature, including stingers, fangs and harpoons, that could work as alternatives for the print nozzle, and zeroed in on the female Aedes aegypti mosquito’s proboscis. This organ is relatively straight, has an inner diameter between 10 and 20 micrometers, and can withstand the pressure of ink being pushed through it.
The researchers’ initial plan was to fit the proboscis into a 3-D printer they could buy from the market. “But it turns out that the pressure that [the biological part] requires might be too high for those commercial printers,” says Cao, of McGill University in Montreal. Instead, they designed a printer around the mosquito proboscis, coating it with a 3-D resin for extra stability and attaching it to an engineered tip to form a continuous pathway for ink to flow through.
To demonstrate the necrobotic tip’s capabilities, the team printed a honeycomb shape, a maple leaf outline and a scaffold to hold biological cell samples, all out of commercially available bioink.
“This biological, nature-derived sample is much better than engineered material,” says coauthor Jianyu Li, a biomaterials engineer at McGill. The best commercially available dispense tips come with inner diameters of 35 to 40 micrometers, double that of the mosquito proboscis nozzle.
Substituting biotic parts for engineering components also boosts sustainability in advanced microengineering. “I’m looking forward to seeing other biotic materials incorporated in the 3-D printing process to enable new capabilities,” Preston says.
Li would like to use the mosquito proboscis in biomedical applications. His lab is interested in developing drug delivery solutions using the proboscis as a microneedle.
