The maglev heart has a positive impact on the quality of life and survival rate of heart disease patients, bringing new vitality and hope to them.
Principles of Maglev Heart
A maglev heart is a device that can partially or completely replace the heart in supplying blood to the body. Its function is not just pumping blood, but also ensuring a smooth and orderly process of blood passing through the pump. Therefore, a nose cone is installed in the pump shell to help guide blood flow, allowing it to smoothly change direction and enter the impeller.
Since the impeller’s rotor is suspended in the pump, there is a gap between the pump shell and the rotor, enabling blood to pass quickly and wash both surfaces in the process, effectively preventing the accumulation of deposits that could form blood clots. Finally, the blood flows out of the outlet pipe under the rotation of the impeller.
Composition of the Maglev Heart
| Hydraulic Pump: This device works on the same principle as hydraulic pumps used in heavy equipment. Simply put, the hydraulic valve continuously opens and closes to allow the required liquid to flow from one side of the artificial heart to the other. When the liquid flows to the left side, the hydraulic pump sends blood to the rest of the body through pressure. When the liquid flows to the right side, the pump uses the artificial ventricle to compress blood to the lungs.
It uses an incompressible liquid to transfer force from one position to another. The gears in the pump rotate rapidly to generate pressure, continuously transmitting blood throughout the body.
| Wireless Energy Transmission System: Also known as Transcutaneous Energy Transmission (TET) system, which mainly consists of two parts: an internal coil and an external coil. When the internal coil senses electrical energy, it transmits the energy to the internal control device and battery. Through magnetic force, it transfers electrical energy from the external battery through the skin to the internal battery (hence “transcutaneous”), enabling these two devices to work together.
| Internal Battery: Simply a rechargeable battery placed in the patient’s abdomen. When the main battery and internal battery cannot interconnect normally, patients can use the internal battery to power certain activities that might involve water, typically lasting 30 to 40 minutes.
| Controller: A small electronic device implanted in the patient’s abdominal cavity, which monitors the heart’s beating speed.
Advantages of Maglev Heart
| Safety: Traditional artificial hearts rely on mechanical bearing rotors to drive the impeller and push blood circulation. These artificial hearts have significant drawbacks because artificial bearings immersed in blood can lead to blood clot formation, posing new risks to patients. However, the fully maglev heart is different. It has no bearings, and the impeller’s rotor is supported and rotated through magnetic levitation technology. With no mechanical friction during operation, its destructive effect on blood is minimal. Blood passes quickly through the pump without damage, maximizing the reduction of blood rejection reactions and avoiding blood clot formation.
| Compact Size: Since the artificial heart is to be installed inside the human body, naturally the smaller, the better. Generally, a fully maglev heart has a diameter of around 70 millimeters, with advanced artificial hearts now achieving a diameter of 50 millimeters, a thickness of only 26 millimeters, and a total weight of just 180 grams. Although small, the maglev heart works with high efficiency, rotating at 1800 revolutions per minute and pumping 4 to 6 liters of blood. To maintain continuous normal operation, the internal battery is certainly insufficient, so while the heart is placed inside the body, the battery can only be placed outside.
Magnets Used in Maglev Heart
Neodymium magnets are widely used in Maglev Hearts. For example, N52 Neodymium-Iron-Boron magnets have a remanence of 1.43T and a magnetic energy product of 52 MGOe. Due to their higher magnetic energy product and coercivity, these magnets can generate stronger magnetic fields in smaller volumes, enabling the miniaturization, lightweight design, and thinning of maglev hearts, promoting their wider use.
Role of Magnets in Maglev Heart
When the motor starts, it generates a rotating magnetic field. This rotating field interacts with internal magnets, forming magnetic coupling, and the driving force is transferred to the internal magnets. The internal magnets are connected to the impeller, so the impeller begins to rotate. As the impeller rotates, it generates centrifugal force, drawing liquid from the inlet into the pump body and then expelling it through the discharge chamber.
Development Direction of Maglev Heart
Although the fully maglev heart has multiple advantages compared to the previous two generations, it still needs improvement. One of the main limitations is the external charging cable. Existing products only support wired charging, which is inconvenient.
Future trends include more convenient charging and further miniaturization of the device.
Magnets Manufacturer
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Image Source: Mayo & Bivacor & Nejm & Researchgate & Wikipedia
