No “nasty” needle necessary: Based on the example of the leech, researchers have developed a suction cup with hidden “teeth” that can gently and effectively draw blood from patients. The concept offers several advantages when used for diagnostics: the bowls do not have such a deterrent effect on sensitive patients and they can even be used by non-medical staff. In addition, they could be mass-produced cost-effectively, say the developers.
Some people get goosebumps just thinking about the common blood draw procedure. Fear of needle use is widespread and children are particularly affected. A comparatively small prick in the fingertip or earlobe can be a gentle alternative in some cases. However, this only creates a small drop of blood, which is not enough for many diagnostic examinations: more sample material is often necessary for the reliability of examination results. Gentle and efficient alternatives to the use of needles have already been developed. But they are usually complex and expensive. The new method developed by a team from the Swiss Federal Institute of Technology in Zurich (ETH) can now score points.
Model leeches
An animal expert in blood drawing provided inspiration: the leech. “We came up with the idea of using this animal as a model to develop a system to obtain blood,” says co-author David Klein from ETH. They analyzed the concept of sophisticated parasites in more detail. An important aspect is that leeches are extremely gentle with their victims so as not to be discovered. To do this, they first attach themselves to the skin using their mouth-suction cup system. They then use their tiny teeth to gently scratch the skin at the point of attachment. In doing so, they create a negative pressure, which causes more blood to come out, which the leeches can then soak up.
The device that the researchers have developed now also works according to this basic principle. It is a suction cup about two and a half centimeters in size made of a flexible silicone material. In the upper part of its interior there is a plastic plate that is equipped with microneedles about two millimeters long. To use it, the suction cup is pressed onto the skin of the patient’s upper arm or back, the developers explain.
The tiny needles then briefly pierce the skin and at the same time air escapes from the interior. After pressing, the silicone dome creates a negative pressure that sucks blood from the small wound into the cavity.
Promising prototype
The researchers tested whether the concept delivers what it promises using young pigs as a model for humans. This confirmed that the suction cup can actually collect blood effectively within a few minutes of being pressed on: enough volume is created to enable diagnostic examinations for which individual droplets from fingertip punctures would not be sufficient. After use, the blood can then be removed from the bowl using a pipette. The researchers have already developed a suitable adapter that can be attached after sampling. The blood obtained can be safely transferred into vessels or directly into an analysis device using a spigot.
According to the developers, the concept has other interesting aspects to offer in addition to its less frightening effect. It can even be carried out by people without medical training and poses less risk of injury to users and waste disposal operators than the classic needle concept. In addition, the researchers emphasize that the disposable bowls could be mass-produced very cost-effectively. They therefore see particular potential for use in developing countries. Specifically, the system could, for example, make an important contribution to the fight against malaria. The achievable blood volume could be sufficient to diagnose the disease.
The researchers are now dedicating themselves to further optimizing their prototype and also want to explore the possibility of using biodegradable materials in order to create a sustainable medical product. They are also hoping for sponsors for further development. This is the only way their bio-inspired blood collection system could soon benefit people with “fear of needles” and patients in structurally weak regions of the world, say the developers.
Source: Swiss Federal Institute of Technology Zurich, specialist article: Advanced Science, doi: 10.1002/advs.202308809