SPEAKER_00: Amazing, fascinating stories of inventions, ideas and innovations. Yes, this is the podcast about the things that have helped to shape our lives. Podcasts from the BBC World Service are supported by advertising.
SPEAKER_01: It's bonus podcast time again. I hope you're enjoying the chance to download and listen to the new BBC World Service podcast, 30 animals that made us smarter. If you are, search for 30 animals wherever you found this podcast. Here's Patrick Ihe with episode three.
SPEAKER_02: Like many people, I would love to become a regular blood donor, but I can't help but dread the thought of a sharp needle piercing my arm. I'm not proud of this, but there's no denying it. Injections with needles hurt. According to the World Health Organization, there are well over 16 billion safe injections every year worldwide. That's a lot of people enduring painful injections every single day. Well, here's something that might just blow your mind. The mosquito, an insect that jabs us with its needle-like mouthparts and feeds on our blood could hold the answer to a future of pain-free injections, which kind of makes sense. After all, the thing about a mosquito is that you may hear it coming, but you rarely feel its bite. All right, enough with the buzzing. Don't worry, you're safe and sound, for now. I'm Patrick Ihe and this is 30 animals that made us smarter. An original podcast from the BBC World Service, which explores how animals have helped us to solve a whole host of technical problems and inspired some amazing inventions along the way. If you've enjoyed our podcast so far, then please spread the word. Tell everyone you know. If they've never listened to a podcast before, show them how to access a podcast app and search for us and show them how to subscribe. If you're able to, it means you'll get all our episodes automatically. And please do leave comments and ratings where you can. The hashtag on social media is 30 animals. Having heard how the Kingfisher inspired the nose of a bullet train and how some very clever colour changing camouflage was inspired by the octopus, in this number three, mosquito and surgical needle, I'd like to share a fascinating story about how the mosquito is helping us to design pain free surgical needles. There are more than 3000 species of mosquito. Yes, 3000. And they're found pretty much in every region across the globe. But with mosquitoes come mosquito borne diseases, which are most prevalent in East Africa, Latin America, India, and Southeast Asia. The word mosquito comes from the Spanish for little fly. And that's exactly what they are a type of fly. Many of us already know what they look like a slender segmented body, a pair of wings, three pairs of hair like legs, feathery antennae, and famously elongated mouthpods. But it may surprise you to know that not all mosquitoes are bloodfeeders. And whilst it's difficult to be sure, a rough guess is that less than 14% feed on human blood. Even so, mosquitoes hold the unenviable title as the world's deadliest animal. And that's because they have the ability to spread viruses and other disease causing microorganisms, which result in millions of deaths worldwide every year. According to the World Health Organization, in 2016, malaria alone, which is transmitted by the Anopheles mosquito was responsible for an estimated 445,000 deaths. Dengue fever, Zika, Chikungunya, and yellow fever are all transmitted to humans by the Aedes aegypti mosquito. With more than half the world's population living in areas where this mosquito is present, you can understand why this little fly has the potential to cause such big problems. When it comes to the culprit, and some of you are not going to like this, but it's the females which are the bloodsuckers. Male mosquitoes feed on nectar or honeydew of plants, but the females need a blood meal before they can lay eggs. It's the proteins in the blood they consume that are crucial for egg development. I've had my fair share of mosquito moments. I remember on one trip to South Africa, it was late at night, and I was about to fall asleep when I heard that dreaded high pitched whining buzz. I turned on the light to try and find the culprit, but there was no sign of it. I flicked off the light. A few seconds later, the buzzing returned. Light on, buzzing stopped, light off. This went on over and over again, and it only got worse when all of a sudden the buzzing fell silent. The tell tale sign that the mosquito had landed and was about to feed. But it's only after they punctured your skin, fed on your blood and left the scene of the crime that you notice a bump appear and the itching begins. The itching is in fact nothing to do with the bite itself. It's actually caused by the bacteria in the anticoagulant injected by the insects to prevent your blood from clotting. When mosquitoes are doing their worst and sucking your blood, you don't feel a thing, which is kind of surprising. And it's all thanks to the design of their mouthparts. You might think that being a mosquito is basically like having a sharpened drinking straw stuck to your face, but it's far more complicated than that. Mosquitoes have several different stylets or probes inside a retractable cover which they use to pierce the skin and penetrate the blood vessels. Together these form the proboscis or mouthparts. Now scientists have been studying the mosquito's marvelous mouth with the aim of designing a pain-free surgical needle. Seiji Aoyagi and his colleagues at Kansai University in Osaka, Japan have developed a needle that mimics a mosquito's proboscis. But what's all the fuss about, I hear you wonder. How is the proboscis any different to a medical syringe? Well, a traditional syringe has a sharp end to pierce through the skin, that bit we all know about, and a smooth surface along its length to allow it to pass through the skin and flesh uninterrupted. The pain you feel when it's inserted in to the skin comes down to the fact that all that metal comes into direct contact with your skin. Now you might think that this would make it even more painful, but it's the complete opposite. Because it's serrated, it makes very little contact with the skin which reduces stimulation of the nerves and as a result you feel less pain. It was only by observing the mouth parts of the mosquito using high-speed video microscopes that the team of scientists could watch the exact sequence of events as a mosquito fed. What they saw was astonishing and eventually they were able to replicate it themselves. Okay vampire lovers, it's time for the insider's guide on exactly how mosquitoes pierce our skin and suck our blood. If you think they're anything like their cartoon depictions of little insects equipped with a set of mini fangs, think again. Mosquito mouth parts are incredibly complex mechanisms, so pay attention. The most obvious part of the mouth is the proboscis, which is made up of several different parts. First, there's the labium. It's a sort of sheath which covers the other mouth parts. When a mosquito lands on the skin, it uses the labium to gently press on the surface of the skin before the other mouth parts are inserted. Next up, the mandibles and maxillae, which are responsible for piercing the skin. Mandibles have pointed ends and go deeper into the skin. Maxillae end in jagged blades, which grip the flesh as they penetrate the host. The mosquito even vibrates its head to work them more easily into the flesh. I know, sounds disgusting, but stay with me. Once in, the mosquito can push against these to drive the mouth parts even deeper. So inside the host are two tubes. One pumps saliva down into the flesh, which numbs the skin, and the other sucks up the blood. But how does the mosquito find her host? Well, it's not by chance. She's actually attracted to carbon dioxide from our breath, our body heat, and various odours from our skin. Once she's landed, she searches for an area where the blood vessels are close to the surface. Some experiments have reported mosquitoes feeding for three to four minutes without their host feeling anything, and they can suck so hard that blood vessels have been known to rupture or collapse. But that's not a problem for the mosquito. Instead, it just drinks blood from the tiny pool that it's created. Okay, we're done. Just talking about it is starting to make me feel queasy. So let's return to Seiji Aoyagi and his team and their attempts to make a pain-free needle. Taking inspiration from the mosquito, they created a needle etched from a material called silicon that was just 1mm long and 0.1mm in diameter. This is really tiny, about the thickness of a human hair. Two harpoon-like jagged-edged outer shanks first penetrate the skin, after which a drug-delivering and blood-sucking tube moves down between them, only touching the patient at its sharpened tip. And just like the mosquito which vibrates its proboscis to help the maxillae ease down through the tissue, their design also mimicked this vibration. Each of the three parts of their device are vibrated by tiny motors. But their intricate design also had to be durable, and in the early stages of development the needles were very brittle, which of course could cause problems if they broke inside the patient. They developed a method of testing their strength by pushing the needle into a piece of silicone rubber which was wrapped around a tube containing red dye. They watched as a tank attached to the needle slowly filled with dye, confirming that the needle was indeed capable of successfully puncturing skin without breaking. Then came the human trials. R. Oyagi tested the needle on himself and a number of other volunteers. They all confirmed that the pain was far less than expected, although it did last longer than injections with conventional syringes. The new needle was also fitted with a 5mm-wide tank to store the blood or fluids it collected. This would enable doctors to analyse the sample using a fibre optic cable connected to the tank. The team hoped that their needle will pave the way for a range of small blood-collecting wireless devices permanently attached to the body. Now that might be something that injects you several times a day, or a needle that you put into your skin and leave there. They could be used for example to monitor sugar levels in people with diabetes, blood cholesterol in those at risk of heart failure, or simply to collect blood samples from patients for diagnosis elsewhere in the lab. And like with the mosquito, you wouldn't feel a thing. But that's not quite the end of our story. Remember I mentioned that whilst the pain was far less than expected, it lasted longer than a conventional needle, well another team may have come up with the answer. Buharat Bhushan and his colleagues at the Ohio State University in the United States of America have been studying the labrum, that's the outer retractable cover of the mouthparts or proboscis, of a female common mosquito in North America called Aedes vexans. They used the technique to probe how hard and stiff the tip of the labrum was in seven different places. They found that the areas nearest the tip and edges were softest. This could be why less pain is caused when the skin is pierced, because it deforms the skin less, so the nerves of the skin send fewer pain signals to the brain. It also turns out that the force with which the mosquito penetrates the skin is three times lower than the lowest reported insertion force for an artificial needle. They might be bloodsuckers, but they're gentle bloodsuckers. Bhushan's team have since proposed a design for a microneedle with two needles inside. One would inject a numbing agent, and another would pierce the skin and either draw blood or inject a drug. This second needle would mimic the mosquito in having a serrated design and vibrate in a similar way to that of the mosquito. The tip of the microneedle would also mirror the flexibility of the mosquito's labrum so that together these features should make for a painless piercing. So next time you hear that high-pitched whine, don't be quite so hasty to curse the culprit. With all the harm they do, the mosquito could be the inspiration for pain-free injections in the future, and they may even help to create devices that constantly monitor and improve our health. It may feel a long way off for countries fighting malaria right now, but it would be good to think that one day the mosquito may be responsible for saving more lives than it harms. In number four of 30 Animals That Made Us Smarter from the BBC World Service, we'll be discovering how a little drumming and a woodpecker's skull is inspiring a new black box which could prove vital for flight investigators in the future. You can find a list of sources of information for this and other episodes on our website bbcworldservice.com slash 30animals. And please do recommend us and let me know what you think. Hopefully nice things. Remember the hashtag on social media is 30animals. Thanks for listening.
