Mosquitoes can teach us about injection techniques

Written by Thomas Hesselberg

Sunday, 28 September 2008

A new study shows that mosquitoes can provide important inspiration for the development of painless medical micro-needles. Photo courtesy of photocase.com.

Engineers from the North Carolina State University in the US have investigated the anatomy and behaviour of biting mosquitoes and modelled how the thin hollow tube, with which the mosquitoes bite, avoids buckling. Their results have implications for the development of micro-needles for medical purposes

Although all animal life forms deserve respect and the right to exist in their natural niche, there are some animals harmful to man, you sometimes would wish did not exist. Mosquitoes are one of these animals. The species Aedes egypti, for instance, is a carrier of several diseases harmful to man such as Dengue fever and malaria, the latter diseases kills more than a million humans annually. However, a new study shows that perhaps we can also make use of Aedes egypti for something positive. The anatomy and the method by which the mosquito injects it proboscis (a long hollow tube which it uses to such up the blood with) could provide useful inspiration for the development of biomimetic micro-needles.

Micro-needles are very useful for medical purposes, because they allow the injection of very small dosages and at the same time they cause much less damage to the tissue (and importantly less pain to the patient) than traditional needles. However, one major problem with micro-needles is that they are very brittle and often buckles and breaks during injection.

The American researchers, therefore, turned to the mosquito in order to learn how it employs its long proboscis to draw blood. They did this by a combination of scanning electron microscopy studies of the anatomy and high speed video recordings of the actual biting behaviour. Finally they modelled the buckling forces mathematically. The engineers found that the elastic tissue at the base of the proboscis was essential for avoiding buckling. However, there is also retractable tissue on the proboscis itself, which in combination with rapid head movements (up to 17 Hz) prior to penetration, further reduces the risk of buckling.

The study thus provides ideas, not least the application of elastic tissue at the base, of how to avoid buckling in long hollow tubes, which can be used in the development of biomimetic micro-needles.

Source:
Ramasubramanian, MK, Barham, OM and Swaminathan, V (2008). Mechanics of a mosquito bite with applications to microneedle design. Bioinspiration & Biomimetic 3. doi:10.1088/1748-3182/3/4/046001.

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