Getting fluid to flow through tiny pipes without being damaged or slowed down is a tricky problem that comes into play in all sorts of places, including in some parts of the blood pumps used during heart surgery. The problem is that walls create friction 鈥� so why not just get rid of them? A new type of liquid pipe does just that, allowing water or blood to flow through it with nearly zero friction.
The liquid tubes were made using a ferrofluid, a liquid containing suspended magnetic particles. Thomas Hermans at the University of Strasbourg in France placed some of this liquid inside a plastic case lined with magnets. By manipulating the ferrofluid with the magnets, a channel in the centre was created where another fluid can flow. It鈥檚 a bit like a garden hose full of water, with the hose stripped off and replaced with another liquid.
The device is known as the QPump. But the liquid tubes themselves have a better name: 鈥淲e call them anti-tubes,鈥� says Hermans.
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They are not just a gimmick. Hermans and his colleagues tested this liquid-in-liquid flow by passing several materials through the device. In one test, they found that honey flowed 70 times faster through their ferrofluidic channels than through a conventional plastic tube of the same diameter.
This could come in handy for studying fluid dynamics, or in pharmaceutical processes that involve manipulating lots of liquids in small amounts.By rapidly adding and removing magnets, the fluid inside the liquid tube can be forced to flow, in a similar way听to the rollers used in peristaltic pumps.
Read more: There is a weird new state of matter that can鈥檛 be stirred or pushed
鈥淲e went to an open-heart surgery, which was interesting to see, for a chemist,鈥� Hermans says. 鈥淭he cardiologists showed us what type of pumps they used to pump blood through the heart. With those, the red blood cells can break, and haemoglobin is released into blood plasma, which triggers all kinds of bad things for the patient.鈥�
In tests using the QPump, Hermans and his team found that the breakdown of haemoglobin in whole human blood was about 11 times lower than in a traditional peristaltic pump.
鈥淚t does allow you to do a peristaltic flow in a gentle way,鈥� says Thomas Russel at the University of Massachusetts Amherst. 鈥淚t鈥檚 unlike other things we鈥檝e seen in the sense that the system is entirely liquid. There鈥檚 no solid, so you effectively have no hard walls.鈥�
He adds that the system may be susceptible to interference from other magnetic fields, but future tests would have to confirm that. Hermans says he and his team are planning experiments to test the effects of using this pump on blood in mice next.
Chemrxiv
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