People who get weak in the knees when seeing a needle are in luck! A new blood collection device uses leeches to greatly improve the comfort of blood drawing...

Are those who feel weak in the knees when seeing the needle during blood drawing blessed?

Inspired by leeches, Swiss researchers released a new blood collection device a few months ago. The device abandons the needles that many people fear, and instead uses a combination of suction cups and microneedles to obtain enough blood with minimal trauma.

Image source: Reference [1]

Leeches have a suction cup in their mouths and many sharp "small teeth" in their mouths. They suck blood by generating negative pressure when swallowing. The new blood collection device developed by ETH Zurich works on a similar principle - it is first attached to the upper arm through a suction cup, and after pressing, the microneedles inside the device will pierce the skin, and then negative pressure can be used to collect blood.

When it comes to leeches, many people may feel scared or find them disgusting, but the scientific research community has been working hard to study the potential therapeutic value of leeches , some of which have been actively used.

Understanding Leeches

Hungry blood-sucking leeches are very sensitive to changes in the surrounding environment, such as light and vibration. When encountering a target host, some leeches in aquatic environments will even "chase" the target animal. They have a suction cup on their head and tail, a small mouth suction cup and a large tail suction cup . When running, the leech's body will constantly "stretch and contract" and crawl forward like a caterpillar, with the front and back suction cups moving alternately until the front suction cup touches the host and successfully sucks it.

Image credit: Chiswick Chap

But don't worry, the land leeches that people encounter while hiking generally don't chase their targets. They often attach themselves to their hosts accidentally. After fixing themselves with the suction cups, the three jaws arranged in a Y shape in the leech's mouth will start to work. Each jaw is like a serrated knife with many small teeth arranged in a row. They move back and forth to cut the host's skin.

Under normal circumstances, when we are injured and bleed, the body will spontaneously activate some physiological mechanisms to stop bleeding: platelets will gather at the damaged blood vessels, and then produce a large amount of thrombin , and a blood clot will form at the wound to further stop bleeding.

However, leeches have their own countermeasures. They release an enzyme called hirudin , which directly inhibits the activity of the host's thrombin, thereby preventing the formation of blood clots in the host's wounds. The blood in the wounds can keep flowing , and the leeches can continue to suck blood. The time they suck blood varies from tens of minutes to several hours.

Some blood-sucking leeches have three jaws in their mouths, which are lined with many small teeth. In the wild, if you find a leech on your body and want to get rid of it, you can use your fingernails to push off the suckers at the head and tail of the leech to make it fall off. Image source: American Museum of Natural History

When leeches swallow, they create negative pressure, which draws blood into their digestive tract. A well-fed leech can swell to five times its previous weight, and sometimes suck up to 10 times its weight in blood . "If the blood coagulates inside it, the leech will fall to the bottom of the water like a brick," said Kvist Currie, senior curator of entomology at the Royal Ontario Museum in Canada.

Hirudin is a powerful anticoagulant. When the leech is full and falls off, the hirudin will still work at the bite site, and the host's wound will continue to bleed for a while. And after the leech is full and leaves, the host's blood in its digestive tract can also not coagulate for a long time. Previously, researchers found that some leeches can survive for a year after sucking blood once!

In English, the word "leech" is also used to describe people who only take and are unwilling to give. However, in fact, not all leeches suck blood. There are also many types of leeches that are predators . They mainly feed on small invertebrates such as snails, slugs, and earthworms. At the same time, in the food chain, leeches are also food for fish, turtles, waterfowl and other animals.

Leeches to help you

In the scientific research community, leeches are the darlings of many researchers, and some researchers even let the leeches in the laboratory suck their own blood. By studying hirudin, scientists are developing drugs with fewer side effects to treat blood clots and prevent strokes . In addition, leeches can also play a role during surgical operations. For example , when a human amputated finger is reattached, leeches can suck blood to allow fresh oxygenated blood to re-enter the severed finger.

To find and collect leeches, some researchers use themselves as bait. When the leeches are full, they fall off and fall into the bags prepared by the researchers. Image source: American Museum of Natural History

Now, a blood collection device developed based on the leech model is expected to help people collect blood more easily. In a study published by the Swiss Federal Institute of Technology in March this year, the suction cup and microneedles of the new blood collection device imitated the mouth suction cup and small teeth of the leech. The suction cup is fixed to the patient's arm, and when pressed, the microneedles inside the suction cup will pierce the skin. After that, the release of pressure in the suction cup will generate negative pressure, which will suck the blood and store it in a storage space containing anticoagulants.

Image source: Reference [1]

Microneedles are less invasive, cause less pain and discomfort, and heal more easily. In addition, because the microneedles are fixed inside the suction cup, they reduce the risk of injury during the puncture process and subsequent treatment compared to traditional blood collection needles. Researchers are also developing a new version of the device made of fully biodegradable materials.

This blood collection device can be used by non-medical professionals. Compared with fingertip blood collection, it can collect more blood , improving the accuracy of diagnosis. In addition, it can be manufactured at a low cost and is easy to carry, so it is very suitable for low- and middle-income areas , and is expected to help people better fight diseases such as malaria .

Malaria is currently diagnosed by taking blood from the patient's earlobe or fingertip and testing it for the presence of Plasmodium. When a mosquito infected with Plasmodium bites a healthy person, the mosquito injects the Plasmodium in its saliva into the body. The Plasmodium then enters the bloodstream. The parasites first invade the liver, where they grow and multiply in liver cells; once mature, they leave the liver and infect red blood cells in the blood.

Malaria can cause fever, chills, headache and vomiting, which can be life-threatening. By checking blood smears for malarial parasites, health care workers can diagnose and monitor malaria infection in patients.

Through blood smears, it can be observed that malarial parasites enter red blood cells and reproduce. On June 30, 2021, my country was certified as a malaria-free country by the World Health Organization. Image source: Lukas.S

Children are at higher risk for severe malaria infection . According to the World Health Organization, children under the age of 5 account for approximately 78% of all malaria deaths in Africa.

But at the same time, the proportion of needle phobia in the population is not low, and children are particularly afraid of needles. It is estimated that about a quarter of adults and up to two-thirds of children have a strong fear of needles. Generally speaking, as people get older, their fear of needles will gradually weaken or disappear.

If you are also afraid of blood collection needles, you might want to look forward to the "leech blood collection device".

Planning and production

Source: Bringing Science Home (id: steamforkids)

Author: Cloud

Editor: Yinuo

Proofread by Xu Lai and Lin Lin