Oct 29, 2018 | By Thomas

Kai von Petersdorff-Campen, a doctoral student in the Department of Mechanical and Process Engineering at ETH Zürich, Switzerland, has developed a 3D printing technique to create products containing magnets. He demonstrated his method, called “Embedded magnet printing,” by 3D printing an artificial heart pump prototype, and won the first prize for prototyping from the American Society for Artificial Internal Organs (ASAIO).

Cross section of the prototype. The dark grey magnetic components are clearly visible. (Photo: Kai von Petersdorff-Campen / ETH Zurich)

“My goal was not to make a good heart pump, but to demonstrate the principle of how it can be produced in a single step,” says Petersdorff-Campen.

Artificial heart pumps are not only geometrically complex products, but, more importantly, they contain magnets – and in the field of 3D printing with magnets, research is still in its infancy. Petersdorff-Campen’s heart pump is therefore one of the first prototypes with magnetic components manufactured using 3D printing.

The 26-year-old doctoral student developed the prototypes this spring. Petersdorff-Campen calls his newly developed method “embedded magnet printing”. The key is to ensure that the magnets are 3D printed directly in the plastic. Magnetic powder and plastic are mixed before printing and processed into strands known as filaments. Using FDM technology, these filaments are printed as the nozzle as the nozzle automatically outputs the computer-generated form, with its various components. The printed pieces are then magnetised in an external field. The plastic heart pump prototype took a total of 15 hours to print.

One of the biggest difficulties was the development of the filaments: the more magnetic powder that is added to the granulate mix, the stronger the magnet, however, this results in a more brittle end product. “We tested various plastics and mixes, until the filaments were flexible enough for printing but still had enough magnetic force,” says Petersdorff-Campen.

Petersdorff-Campen published his work in an academic journal. The reactions varied, he explains: “Some people are already asking where they can order the material.” Some people criticised that the 3D printing is not suitable for the production of medical devices, because of the various approval processes they must go through. “That was not my focus, however,” emphasises Petersdorff-Campen. “I simply wanted to show the principle.” He is sure that it is worth further development by scientists and developers.

Flexible filament consisting of a polymer-magnetic powder mixture (Photo: Kai von Petersdorff-Campen / ETH Zurich)

Even though his method may not be suitable for fabricating heart pumps, the potential of 3D printing of magnets is huge. Magnets are also used in electric motors, such as those in numerous technical household devices, from a computer’s hard drive to loudspeakers and microwaves. Today, geometrically complex components with magnets are produced by complex injection moulding, but using 3D printing instead could make this process significantly faster and less expensive.

However, that is still a long way off, says Petersdorff-Campen: “There is still a lot to improve in terms of material and processing.” For example, his heart pump was able to successfully pump 2.5 litres per minute with 1,000 rotations, but this does not yet meet the standards required in practice: “I wouldn’t want to have such a device implanted.”



Posted in 3D Printing Application

Source: ETH Zurich


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