Parasitic wasp inspires advancements in surgery
Flexible, ultra-thin and steerable needles would help surgeons perform operations even better. Researchers at Wageningen University & Research are therefore studying the ovipositor with which the parasitic wasp lays its eggs. Based on their findings, colleagues at Delft University of Technology have developed the first prototype of this needle which is the thinnest needle in the world. Solutions found in nature are often the source of human inventions such as self-cleaning paint and underwater robots.
During medical procedures, it is important to cause as little damage as possible to tissue, nerve bundles and blood vessels. This can be especially complicated in brain surgery or surgery performed around the spinal cord. Researchers from Delft University of Technology are therefore working on the development of an ultra-thin, flexible and steerable needle. They asked their colleagues at Wageningen University & Research for possible solutions inspired by nature. They in turn turned to the parasitic wasp for inspiration.
The parasitic wasp lays its eggs in the larvae of other insects which are often hidden inside plants or fruit. The parasitic wasp inserts the eggs through a narrow, hollow tube-like structure at the end of her abdomen called the ovipositor. She uses this to pierce through obstacles until she reaches the larvae into which she can insert her eggs. These larvae then become the food for the larvae of the parasitic wasp. The ovipositor of the parasitic wasp is unique, as it is exceptionally flexible.
The researchers filmed the parasitic wasps as they deposited their eggs in clear gels. They observed that the ovipositor was able to bend in all directions to nearly 180 degrees and is even able to make an s-bend. This allows the wasp to move the ultra-thin ovipositor around harder parts in the plants or fruits and steer it precisely towards her goal. It is this flexibility and steerability that surgeons are looking for in their surgical needles.
“The ovipositor is based on a clever digging technique, as it digs its way inside,” explains Sander Gussekloo, an enthusiastic researcher from Wageningen. Gussekloo and his colleagues discovered how the three moveable segments that make up the ovipositor (one at the top and two below), are moved alternately. “By constantly sliding out the bottom part further than the top part, the wasp is able to make bends and move around corners.”
The thinnest needle in the world
In Delft, the first prototypes of the steerable needles have been created. These are the thinnest needles in the world. Each needle consists of seven wires that can move and slide independently. This new needle therefore has even more parts than the ovipositor of the parasitic wasp. However, the needle is not yet able to take such sharp turns, notes Gussekloo. “Materials that are stuck together by human effort are still not as flexible as organic materials. The ovipositor has a natural variation in flexibility that we are not yet able to copy. But the prototype developed at Delft University of Technology is the first step in the right direction.” Gussekloo is still researching exactly how the parasitic wasp steers the ovipositor. “She can manoeuvre the ovipositor in any direction. The ovipositor does not contain any muscles and the wasp directs it using the muscles in her abdomen. But the question remains: how?”
Sticky tree frogs
Delft University of Technology and Wageningen University & Research are working together in multiple areas on the development of new technologies for the medical sector. Gripping wet tissue and organs is something that remains problematic during medical procedures and may cause damage. Scientists are therefore currently investigating the grip ability of tree frogs, who can hold on the slippery surfaces such as wet leaves thanks to the special structures on their foot pads. Wageningen University & Research and Delft University of Technology want to use this natural ability to develop pincers with which wet tissue can be gently gripped.
“ The great thing is that, through millions of years of evolution, nature has come up with solutions. So, we only need to reproduce these solutions. Yet, this is not as easy as it may sound. ”
There are currently many successful examples of bio-inspired design, such as self-cleaning paint that was inspired by the top-layer of the leaves of the lotus plant and ‘fast’ swimwear designed based on the skin of sharks. Wageningen University & Research primarily works on such projects following a request from a university of technology or a company. Engineers are currently working on underwater robots for which scientists looked to the swimming techniques of sea horses and Cephalopoda. “Rotors in underwater drones kick up the sand on the sea floor, so colleagues are looking for different ways of swimming and remaining stationary,” explains Gussekloo.
“The great thing is that, through millions of years of evolution, nature has come up with solutions for problems that people face today. So, we only need to reproduce these solutions. Yet, this is not as easy as it may sound,” says Gussekloo. He feels that it is a unique experience to be able to help develop the steerable needle which will be used in many medical procedures in the future. “If a manufacturer is interested and wants to start producing the needle, further development may speed up significantly.”