3D-printing with incorporated iron particles for magnetic actuation and MPI

Magnetic particle imaging (MPI) scanners cannot only be used to image the distribution of magnetic nanoparticles, but the magnetic fields also facilitate to actuate magnetic devices. This enables the dual use of MPI scanners for simultaneous actuation and visualization of magnetic objects. It is of great interest for a variety of medical applications to magnetically steer devices, such as catheters or capsule endoscopes. Endoscopic capsules, which are driven by the natural peristaltic movements, are already in clinical routine. However, they cannot be used for the investigation of the stomach, since the capsules cannot be steered. Hence, steerable magnetic capsules can be used to endoscopically investigate the whole gastrointestinal tract, to take a biopsy or to deliver drugs locally. The 3D tomographic localization of such steerable capsules is an open task, but it is essential to localize detected abnormalities for subsequent treatments. Since MPI provides tomographic real-time images of magnetic material, it seems to be beneficial to visualize the actuation process with MPI. In this work, a material for additive manufacturing is investigated, which consists of polylactide with incorporated iron powder of µm-sized particles. The material is analyzed by light microscopy, vibrating sample magnetometry and magnetic particle spectrometry. Then the feasibility to actuate and visualize macroscopic devices made of this material inside an MPI scanner is shown. The fabricated object has a length of about 2 cm and can be rotated when applying sinusoidal currents to the focus field coils of an MPI scanner. In addition, the objects’ shape led to a forward velocity in water. The suitability of the 3D-printing material for MPI is shown and static 3D images are presented.