Drawing inspiration from the unique blood-sucking methods of aquatic leeches, Swiss researchers have developed an innovative needle-free blood collection device, which is undoubtedly good news for those who are squeamish at the sight of blood collection needles. This device integrates suction cup and microneedle technologies, which allows it to effectively collect a sufficient amount of blood with minimal harm.

The principle of this new blood collection device is similar to the feeding mechanism of leeches. It first adheres to the upper arm of a person through a suction cup. Then, the microneedle system is activated, piercing the skin and creating a vacuum to draw blood. Leeches might not be aesthetically pleasing, but due to their potential medical value, they continue to be the subject of ongoing scientific research and have been partially applied to actual treatments.

Leeches are particularly sensitive to environmental changes such as light and vibration, and they have a suction cup at both their head and tail, which they use to move in water and capture their hosts. When the suction cups are firmly attached to the host, the mouth of the leech opens into a Y-shaped formation of three jaws and begins its work, using the serrated small teeth on the jaws to saw through the skin.

Normally, when the human body is injured, it initiates a coagulation mechanism to stop the bleeding as soon as possible. However, leeches secrete a substance called hirudin to block the host's coagulation mechanism, ensuring blood flow so that they can continue to suck blood. This process can last from several minutes to several hours.

In addition, it's worth noting that if one is accidentally attached by a leech in the wild, they can be removed by pushing away the suction cups at their head or tail. Furthermore, leeches gorged with blood can swell up to ten times their original body weight, and if the blood coagulates inside them, they will sink to the bottom like bricks, according to Kvist Currie at the Royal Ontario Museum.

Hirudin is a potent anticoagulant. It continues to act at the site of the bite after the leech has fed, causing the wound to bleed for a while after the leech detaches. Similarly, it also keeps the blood in the leech's digestive tract in a liquid state for a longer time. Initial studies suggest that leeches can survive for up to a year after a single feeding. In the English context, the term "leech" not only refers to this creature but is also used to describe those who incessantly take without a willingness to give. However, not all leeches feed on blood; many species are predators that eat small invertebrates such as snails, slugs, and earthworms. Moreover, leeches themselves are part of the food chain for many animals like fish, turtles, and waterfowl.

In the field of scientific research, leeches are beloved by many researchers, with some even willing to serve as the blood source for laboratory leeches. Scientists, through in-depth studies of hirudin, are working hard to develop new medications for treating thrombosis and preventing strokes with fewer side effects. Additionally, in surgical procedures, the usefulness of leeches is not to be underestimated—for example, in finger reattachment surgery, leeches can promote the flow of fresh oxygenated blood and help with wound healing.

To capture leeches, some researchers are even willing to use themselves as bait, waiting for the leeches to drop off after feeding, then collecting them into containers prepared in advance. The unique characteristics of leeches, inspire scientists to develop new medical devices. Researchers at ETH Zurich have developed a new type of blood-sampling device, inspired by the leech's sucker and its tiny teeth. This blood-sampling device is fixed to the patient’s arm with a suction cup, and when pressure is applied, embedded microneedles gently touch the skin surface and pierce the dermal layer, then by using negative pressure blood is drawn into a collector containing anticoagulant.

The benefits of using microneedles include their minimal invasiveness, lesser discomfort caused, and faster healing of the wound. Also, because the microneedles are fixed inside the suction cup, compared with traditional blood-sampling needles, the risk of injury during puncture is significantly reduced. A new version still in development, made entirely of biodegradable materials for ease of use by the general public, not only allows for more blood collection than fingertip sampling to improve diagnostic accuracy but also can be manufactured at a lower cost for portability, providing more efficient disease-fighting options in low- and middle-income regions.

At present, the main method for diagnosing malaria is the collection of blood samples from the earlobe or fingertip to detect the presence of malaria parasites. During the infection process, when an infected mosquito bites a human, it transmits the malaria parasites carried in its saliva into the human bloodstream. Initially, the malaria parasites invade the liver to reproduce, then leave the liver to infect red blood cells. Once infected with malaria, symptoms such as fever, chills, headache, and vomiting may occur, and in severe cases, it can be fatal. Therefore, observing blood samples to diagnose and monitor the infection status of patients is a crucial task.

Blood smears are a common method used for observing malaria parasite infections. Through this technique, it is possible to observe the malaria parasites invading human red blood cells and reproducing within them. It is worth noting that on June 30, 2021, China was recognized by the World Health Organization as a malaria-free country.

Malaria is one of the serious health problems facing the world, especially for children. According to the World Health Organization, children under the age of 5 in Africa account for about 78% of all malaria deaths. However, while actively preventing and treating malaria, many people, especially children, have a great fear of needle injections. Surveys have shown that about one quarter of adults and up to two-thirds of children feel a strong fear of needles.

Such fear may diminish or disappear as one grows older, but it is still a problem that cannot be overlooked. In response to this, scientists have begun to research and develop new blood-sampling techniques, including a blood-sampling device inspired by leeches. This innovative device is expected to achieve a more gentle method of blood collection for patients.

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