Device, system and method for generating a 3D structure

Abstract

Device (16) for manufacturing a 3D structure (12) from a starting material (14) with a magnetocalorically excitable substance (42), based on CAD / CAM data (34) relating to the 3D structure (12), comprising: • a working area (18) for receiving the starting material (14) to be processed; • a control unit (28) with a memory (32) for the CAD / CAM data (34) of the 3D structure (12) to be produced; • a gradient field generator (20) for generating a gradient field (38) by which a defined field-free space (40) in the starting material (14) arranged in the working area (18) can be spatially encoded and by which the magnetocalorically excitable substance in the starting material outside the field-free space (40) is positively or negatively magnetically saturated; and• an alternating field generator (22) for radiating a frequency- and amplitude-modulated alternating field (44) into the working area (18);wherein the control unit (28) is configured to control the alternating field generator (22) such that the magnetocalorically excitable substance (42) of the starting material (14) can be excited in the spatially coded field-free space (40) by means of the alternating field (44) in order to: • in the case of a starting material (14) comprising a prepolymer (14a) thermally induced polymerization of the prepolymer (14a) to a polymer; and / or • in the case of a starting material (14) comprising a ceramic material (14b) and / or a metallic material (14c) sintering of the ceramic / metallic material; or • or thermal structural decomposition of the starting material (14), preferably alone, induce in the defined field-free space (40).

Description

The present invention relates to a device, a system, and a method for generating a three-dimensional (= 3D) structure. Furthermore, the invention relates to a use of the device and the system. In so-called 3D printing (additive manufacturing), a three-dimensional structure is produced layer by layer under computer control from one or more liquid or solid materials according to predefined dimensions and shapes. During the build process, physical or chemical hardening and / or melting processes take place. Typical materials for 3D printing include plastics, resins, ceramics, and metals. 3D printing is characterized by the cost-effective customization of 3D structures in terms of geometry, material, and functionality, combined with a high degree of automation and decentralization in manufacturing. Based on CAD-optimized image files, various additive manufacturing technologies now enable the controlled, reproducible, and real-time modulation of three-dimensional structures through increasingly precise material deposition in a design-adapted coordinate system. The dimensional accuracy of 3D structures produced using established 3D printing methods is still insufficient for numerous applications. Furthermore, subsequent post-processing of 3D-printed structures using other conventional machining or manufacturing methods is often very complex and can only be carried out to a limited extent, if at all, within the structure itself. Reference is made to the revelation in DE 10 2021 211 395 A1 , DE 10 2021 205 350 A1 , US 2012 / 0 329 659 A1 , US 2013 / 0 056 672 A1 and DE 10 2018 116 790 A1. Object of the invention The object of the invention is to provide a device and a system by means of which a predetermined 3D structure can be manufactured (produced) contactlessly, without interrupting the manufacturing process and with high resolution, by processing a starting material. Furthermore, the object of the invention is to provide a method for manufacturing a 3D structure. Solution to the problem according to the invention The problem relating to the device is solved by a device having the features specified in claim 1, and the problem relating to the system is solved by a system having the features specified in claim 6. The method according to the invention is specified in claim 7. Advantageous further developments of the invention are the subject of the dependent claims and the description. Device according to the invention Independent of the technical process principles of the 3D printing systems and methods described above, an inventive device is proposed by means of which a 3D structure based on CAD / CAM data of the 3D structure is enabled by processing a starting material comprising a magnetocalorically excitable substance. The magnetocalorically excitable substance is preferably homogeneously or substantially homogeneously distributed within the starting material. The magnetocalorically excitable substance is discussed in more detail below. The device includes a work area for receiving the raw material to be processed. A control unit serves to control all operating parameters of the device. The control unit includes a data storage device for the CAD / CAM data of the 3D structure to be produced. The control unit can, in particular, be a computer (with an input unit, a display, an operating system, and application software for controlling the device). The device's data storage device can, for example, be in the form of an optical, electronic (semiconductor memory), magnetic, or magneto-optical data storage device, all of which are generally known in computer technology. The device further comprises a first gradient field generator for generating a gradient field, i.e., a statically or dynamically inhomogeneous magnetic field, by which a defined field-free space ("field-free region") in the work area, and thus in the starting material arranged in the work area, can be spatially encoded (three-dimensionally spatially resolved) based on the CAD / CAM data. A field-free space is understood to be a space in which an isolated zero magnetic field prevails. The device according to the invention further comprises a (controllable) frequency-modulated alternating field generator for radiating an alternating magnetic field (possibly an RF field) into the working area. This alternating magnetic field thus serves to introduce energy into the starting material to be processed during the manufacturing process for the purpose of processing it. Due to the frequency modulatability of the alternating field generator, it can emit alternating fields of different frequencies. With regard to the gradient field generator and the alternating field generator, the device according to the invention and the method according to the invention explained below selectively utilizes a partial aspect of so-called Magnetic Particle Imaging (=MPI imaging) in order to spatially encode the spatial coding of the field-free space accessible for additive or subtractive manufacturing in the starting material to be processed in three dimensions and to excite the magnetocalorically excitable substance arranged in the FFR. Magnetic particle imaging (MPI) was developed from 2001 onwards for medical imaging diagnostics and, alongside MRI and CT, was first published in "Nature" in 2005 as another tomographic method for tracer-based real-time imaging (Gleich B, Weizenecker J, Borgert J. 2005, Tomographic imaging using the nonlinear response of magnetic particles. Nature. 435.7046 (2005), pp. 1214-1217; DOI: 10.1038 / nature03808). Magnetic particle imaging (MPI) is based on the nonlinear magnetization behavior of superparamagnetic iron oxide nanoparticles (SPIONs) introduced into the body under the influence of at least two superimposed, different magnetic fields. A classic example is the liver-specific MRI contrast agent Resovist™, used in combination with a strong static gradient field and a homogeneous alternating electromagnetic field. Along the gradient field, all SPIONs are either positively or negatively magnetically saturated, except for a defined position where an isolated zero magnetic field prevails. In this so-called field-free region (FFR), the SPIONs exhibit no or incomplete magnetic saturation. Unlike all other SPIONs outside the field-free region, they are therefore susceptible to remagnetization and remagnetization, which they undergo through an additionally applied alternating magnetic field.This phenomenon is used exclusively for imaging at the MPI. It generates a signal in receiving coils that is linearly dependent on the local particle concentration; these coils can be identical to the transmitting coils. Using digital reconstruction steps (e.g., harmonic-space or x-space algorithms), position-specific spectral fingerprints in the frequency domain can be calculated from the acquired measurement data. This allows for both the spatial localization of the signals and a precise quantitative analysis of further information about the environmental conditions of the particles in the FFR. These results can be visualized in 1D, 2D, and 3D. They provide information, in particular, about the spatial concentration distribution of the particles, but also about the temperature, bonding conditions, and viscosity of the particle-containing medium.The basis for this is the characteristic nonlinear magnetization dynamics of the particles used, which depend on the local physicochemical conditions and can be visualized down to the molecular level when using a variety of different alternating field frequencies. Even small field strength differences can shift the susceptibility of the particles into or out of the plateau-like region of the saturation curve, resulting in a more or less sharp offset in excitability. Although the MPI does not enable anatomical imaging, it offers extremely high temporal resolution (> 40 volumetric images per second), sensitivity (890 pg, or < 100 labeled cells), and an outstanding contrast-to-noise ratio without the use of ionizing radiation.In addition, compared to MRI, it has a 104-fold lower susceptibility to artifacts and theoretically unlimited penetration depth, while simultaneously requiring less power and a less demanding field generator design, which should even make mobile variants feasible. To acquire data from different locations within the volume of space, it is necessary to move the FFR across the volume of the study. At the MPI, this is achieved using mechano-kinetic devices along at least one spatial axis. More elegantly, albeit on a smaller scale, FFR translation can also be controlled electromagnetically by superimposing additional magnetic fields (drive fields or focus fields), as follows. First, the volume under investigation is exposed to a strong selection field, classically a strong static gradient field (0.2–7 T / m), or alternatively a so-called traveling wave (see TW-MPI). The FFR defined in this way can be reduced or increased by choosing the gradient strength along the gradient. An additional homogeneous (reversible) or very slowly undulating magnetic field can then displace the FFR along its plane (e.g., the x-axis). Further additional homogeneous (reversible) or very slowly undulating magnetic fields in other spatial directions—ideally orthogonal to each other and to the x-axis field (i.e., the y-axis or z-axis)—can shift the FFR in its direction. In this way, the primarily point-like orEllipsoidal FFRs can be freely navigated throughout space. The so-called excitation field, i.e., an additional superimposed fast alternating field (1–100 kHz; < 50 mT), primarily leads to magnetization changes of the SPIONs within the FFR, with its field strength potentially having a relatively minor influence on the FFR position. Using further directionally different gradient fields—comparable to the original selection field—it is possible to modulate the geometry of the FFR in other spatial directions, e.g., linearly, and to refine its offset through rotation, thus generating higher temporal and spatial resolutions (micrometer dimension). Furthermore, additional homogeneous and inhomogeneous fields, known as shift fields and saturation fields, can contribute to optimizing the precision of the method.These are appropriately instrumentalized and combined to realize complex multidimensional trajectories, on which the scanning schemes of modern imaging sequences are based. The MPI scanner design is also constantly evolving. In addition to closed, semi-open, and open systems, there are also single-sided (e.g., coplanar) and even mobile devices. Depending on the desired target parameters, these can be constructed by combining different magnetic field coils with varying sizes, winding densities, geometries (e.g., Helmholtz or Maxwell ring coils), materials, and arrangements, as well as by combining them with permanent magnets or functional modules composed of smaller permanent magnet units (e.g., Halbach arrays). These modules often contain elements that rotate independently or relative to each other and can be energized in both the same and opposite directions and interconnected with other reactive elements. Further detailed information on Magnetic Particle Imaging can be found in particular in: Timo F. ​​Sattel: Scanner topologies and optimization of field sequences for Magnetic Particle Imaging (Research Series of the Institute of Medical Engineering: University of Lübeck) Infinite Science GmbH, Lübeck 2018 (ISBN 978-3-945954-49-2 ). While MPI uses a static gradient field for spatial encoding of the FFR, the device according to the invention has a modulatable gradient field generator in this respect, by which a gradient field that can be modulated with respect to the field strength gradient can be generated. In contrast to the scanners used in Magnetic Particle Imaging, the control unit of the device according to the invention is configured or programmed to control the RF field generator in such a way that the magnetocalorically excitable substance of the starting material can be magnetocalorically excited in the spatially coded field-free space by means of the RF radiation in such a way that a) in the case of a starting material comprising a prepolymer, a thermally induced polymerization of the prepolymer; and / or b) in the case of a starting material comprising a ceramic material and / or a metallic material, a sintering of the ceramic / metallic material; or c) preferably in the case of a starting material comprising a polymer material and / or a metallic material, a thermal structural decomposition of the starting material, preferably alone, can be triggered or effected in the defined field-free space. The system according to the invention comprises the aforementioned device and the starting material to be processed, containing the magnetocalorically excitable substance. The gradient field can cause the magnetocalorically excitable substance in the starting material to become either positively or negatively magnetically saturated. Only in the field-free space (FFR) defined by the CAD / CAM data, where an isolated zero magnetic field prevails, does the magnetocalorically excitable substance exhibit no or incomplete magnetic saturation. In contrast to the magnetocalorically excitable substance in the remaining starting material outside the field-free space (FFR), this substance is therefore susceptible to remagnetization and remagnetization, which it undergoes through the additionally applied alternating magnetic field. The energy input of the preferably frequency-modulated alternating magnetic field required for polymerizing / sintering or decomposing the starting material in the FFR, as well as its respective parameterization (amplitude, frequency, duration, etc.), must be determined experimentally for the specific starting material and the magnetocalorically excitable substance used. The control unit is programmed to control the (frequency-modulated) alternating field generator based on this experimentally obtained data. Further details can be found below. In summary, the device according to the invention enables multifunctional processing of the starting material for the production of 3D structures of any geometry, structure, surface design, and, depending on the specific starting material used, also with predefined material properties. Single- and multi-stage post-processing procedures are possible. All of this takes place in just one process chamber. Using this device, a 3D structure defined by CAD / CAM data can be created from the starting material using additive and / or subtractive manufacturing processes. Furthermore, the device enables post-processing of the 3D structure. Examples include microscopic and / or macroscopic surface texturing or curing of the starting material into a (partially) polymerized 3D molded part. The device allows for the modulation of the material properties of the 3D structure, either in specific areas or across the entire structure. The device or system can also be used for coating a molded part, joining two molded parts, or repairing a damaged molded part.By using so-called self-healing plastics as a starting material, such as vitrimers, it is possible to create 3D structures with so-called self-healing properties that were previously impossible or difficult to realize, or to authentically repair / heal them. According to a preferred embodiment of the invention, the device comprises a mechanical motion device for, preferably, multi-axis spatial movement or repositioning of the defined field-free space FFR relative to the working area or the starting material to be arranged therein. By means of the motion device, a mechanical relative movement of the gradient field and the working area or the starting material to be arranged therein is thus achievable. This allows the field-free space FFR to be positioned at different locations, i.e., different volumes of interest (VOI), preferably along or around all three spatial axes X, Y, Z, in different positions / spatial orientations for processing the starting material. Alternatively or additionally, the device can have another magnetic field generator for generating a further magnetic field, or even several further magnetic field generators for generating several further homogeneous magnetic fields (drive fields) B1, B2, B3, which can be superimposed on the gradient field in order to spatially reposition the field-free space relative to the working area / starting material. This is undoubtedly a more technically complex solution than the aforementioned mechanical movement device, but offers advantages, particularly with regard to the rapid repositioning of the field-free space to a different volume of interest (VOI) to be processed in the starting material. If the device has at least two, preferably several additional, magnetic field generators for generating inhomogeneous magnetic fields G1, G2, G3 (...Gn), which are preferably aligned orthogonally to each other, then the geometry (=geometric shape) / size of the field-free space can be defined or varied by means of these, particularly based on the CAD / CAM data. It is understood that in the case of more than three magnetic field generators, their magnetic fields can also be aligned at least partially at an angle of less than 90° to each other, for example, 45°. By means of such additional inhomogeneous magnetic fields, the field-free space FFR can be generated – preferably depending on the CAD / CAM data of the 3D structure to be manufactured – with a continuously graduateable point, line, surface, and volume geometry. This allows for particularly rapid processing of the starting material, tailored to its size and geometry. The control unit of the device is programmed to control the mechanical motion device and any additional magnetic field generator based on the CAD / CAM data for the 3D structure to be produced. According to the invention, the field frequency of the alternating field emitted by the frequency-modulated alternating field generator is between 1 kHz and 1 GHz, preferably between 10 kHz and 1 MHz, and most preferably between 100 kHz and 500 kHz. In this respect, it can be referred to as an RF field. At these field frequency intervals, the magnetocalorically excitable substance can be reliably magnetocalorically excited to ensure the polymerization / sintering or decomposition of the starting material in a defined field-free space. According to the invention, the device preferably has at least one imaging device, i.e., a device for acquiring image data. The imaging equipment may include: • a laser scanner, • one or more CCD cameras or • one or more infrared cameras, • a magnetic resonance imaging (MRI) scanner, • a computed tomography (CT) scanner, • a digital volume tomograph, • a sonography device, and / or • a positron emission tomography (PET) scanner. The control unit of the device preferably has an operating mode for acquiring and evaluating image data using the imaging device. This allows the device to perform image-based analysis and monitoring of the machining process or the (partially) manufactured 3D structure during the machining process, possibly in real time. If the device includes an MRI scanner, MRI-based thermometric data can be acquired from the work area, i.e., the starting material to be processed or the (partially) manufactured 3D structure. This thermometric data can be taken into account when generating the 3D structure, for example, when determining the duration or intensity of the RF field to be applied to excite a defined voxel. If the device is set up for imaging using the Magnetic Particle Imaging (MPI) method described above, the distribution and concentration of the magnetocalorically excitable substance within the starting material can be measured, and a sufficiently homogeneous distribution and concentration of the magnetocaloric substance in the starting material can be verified. This is advantageous for quality assurance during the production of the 3D structure. Furthermore, the spatial distribution and quantity of the starting material to be arranged in the working area, or of the generated 3D structure, can be determined more easily within the working area. In additive manufacturing processes, thermodynamic phenomena are known to be a significant source of artifacts, the effects of which must be controlled as effectively as possible. This is essential to prevent both microdimensional losses in detail resolution and macrodimensional structural inhomogeneities and irregularities in the 3D structure. Thermosensitive sequences within the framework of so-called MRI-assisted HIFUS (high-intensity focused ultrasound) treatments have since proven their clinical practicality and reliability. The proton resonance method, in particular, is characterized by high spatial, temporal, and thermometric resolution and reliability, and is therefore also suitable for monitoring the manufacturing process in order to detect unfavorable heat dissipation or accumulation in three-dimensional space at an early stage. According to the invention, the device can be designed to perform such thermosensitive sequences. The control unit preferably includes a software application by which absolute temperature values ​​can be determined and preferably color-coded based on the data obtained within the framework of the thermosensitive sequences, user-defined topographic and thermal thresholds can be linked to alarms in a location-specific manner, and compliance with precise exposure dose limits can be automated or semi-autonomously regulated. Starting material According to the invention, the starting material can be designed as a prepolymer (for the purpose of additive manufacturing) and comprise monomers and / or oligomers and / or polymers which polymerize by way of thermal polymerization, i.e. by the action of thermal energy. The polymer precursor can comprise, in particular, industrially available biopolymers, preferably in purified form. These allow for the sustainable production of the 3D structure and are also characterized by high biocompatibility. According to the invention, polysaccharides, glycosaminoglycans, polypeptides, and / or proteins, for example, are suitable. In particular, alginates, hyaluronic acid, collagens / gelatin, chitosan, fibrin, silk fibroin, cellulose, and even derivatives of the human extracellular matrix (ECM derivatives) and so-called (bio-)artificial polymers are conceivable. Marine collagens, for example from fish waste (fish gelatin metacrolyl = FGelMa), are also conceivable. Artificial (plastic) polymers or prepolymers, in turn, exhibit high mechanical stability and precisely modulatable properties (e.g., defined degradation rate). This includes traditional materials from biotechnology and pharmacology, but also increasingly established substances from the plastics processing industry, some suitable examples of which are listed below: PLA (polylactic acid), PEG (polyethylene glycol), PCL (polycaprolactone; a very good starting material for inorganic bioceramics), PGA (polyglycolic acid), PLGA (poly(-lactide-co-glycolide), PEO (polyethylene glycol), PPO (polyphenylene oxide), PU (polyurethane), PEEK (polyetheretherketone), polyamides (nylon; + / - polyester), PCU-Sil (polycarbonate-based urethane silicones), PUU (polyurethane), SMP (shape-memory polymers), acrylonitriles (e.g., ABS: acrylonitrile butadiene styrene), block copolymers, liquid crystal polymers. The starting material can be selected in particular from the group of thermosets, elastomers, thermoplastics, vitrimers or their prepolymers. The thermoset resin should have at least one thermosetting functional group, e.g. epoxy group, glycidyl group, isocyanate group, hydroxyl group, carboxyl group, amide group; in addition, the thermoset resin may contain acrylic resin, polyester resin, isocyanate resin, ester resin, imide resin or epoxy resin. Aromatic, aliphatic, linear, or branched epoxy resins can be used, e.g., with an epoxy content of 180 g / eq to 1000 g / eq and two or more functional groups. Such an epoxy resin can consist, for example, of one or a mixture of two or more cresol novolac epoxy resins, a bisphenol A epoxy resin, a bisphenol A novolac epoxy resin, a pheno-novolac epoxy resin, a tetrafunctional epoxy resin, a biphenyl-type epoxy resin, a tripheno-methane-type epoxy resin, a naphthalene-type epoxy resin, a dicyclopentadiene-type epoxy resin, or a dicyclopentadiene-modified phenol-type epoxy resin. Preferably, the epoxy resin has a cyclic structure, preferably with an aromatic group (e.g., a phenyl group). This enables excellent thermal and chemical stability. In particular, one or a mixture of two or more biphenyl-type epoxy resins, a dicyclopentadiene-type epoxy resin, a naphthalene-type epoxy resin, a dicyclopentadiene-modified phenol-type epoxy resin, a creso-based epoxy resin, a bisphenol-based epoxy resin, a xylolylene-based epoxy resin, a polyfunctional epoxy resin, a phenol-novolac epoxy resin, a triphenol-methane-type epoxy resin, or an alkyl-modified triphenol-methane epoxy resin can be used. In the case of a thermoset polymer or a thermoset prepolymer, this can include a monopolymer epoxy resin or phenolic resin or amino resin or unsaturated polyester resin, acrylic resin, maleimide resin, cyanate resin. Suitable thermoplastic polymers include, in particular, expanded thermoplastic polyurethane (eTPU), expanded polyamide (ePA), expanded polyethylene block amide (ePEBA), polylactate (PLA), polyether block amide (PEBA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and thermoplastic polyester ether elastomer (TPEE). The starting material can further comprise at least one of the following groups: polyamides, polyesters, polyetherketones, polyolefins. Polyamides are one or more of the homopolyamides, copolyamides, polyetherblock amides, or polyphthalamides. Polyetherketones are one or more of the polyetherketones (PEK), polyetheretherketones (PEEK), polyetherketoneketones (PEKK), polyolefins of one or more polypropylenes (PP), polyethylene (PE), olefin coblock polymers (OBC), polyolefin elastomers (POE), polyethylene covinyl acetate (EVA), polybutene (PB), or polyisobutylene (PIB), as well as suitable chain extenders. Furthermore, the starting material can include one or more of the following substances: polyoxymethylene (POM), polyvinylidene chloride (PVCD), polyvinyl alcohol (PVAL), polylactate (PLA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene (FEP), ethylene tetrafluoroethylene (ETFE), polyvinyl fluoride (PVF), perfluoroalkoxy (PFA), and thermoplastic urethanes (TPU), for example, also PBT (polybutylene ternophthalate). At least one polymeric material with epoxy groups, pyrromelletic dianhydrides, styrene maleic anhydrides, or combinations thereof must be used as a chain extender; in particular, styrene-acrylate copolymer with reactive epoxy groups can be used. Furthermore, polyamides (PA) and polyether block amides are used. The chain extender is a polymer material with epoxy groups, pyromellitic dianhydrides, styrene maleic anhydrides, or a combination thereof, in particular styrene-acrylate copolymers with reactive epoxy groups, but thermoplastic polyester ether elastomers (TPEE) are also suitable. The usable chain extender consists of at least one polymer material with epoxy groups, pyromellitic dianhydrides, styrene maleic anhydrides, or combinations thereof, in particular a styrene-acrylate copolymer with reactive epoxy groups. DGEBA epoxy, the most widely processed thermoset resin for the production of epoxy and phenolic resins, which can be blended with other polymer resins, is also suitable. Suitable hardening agents include, for example, polyamines, aminoamides, and phenolic compounds. So-called vitrimers, novel glass-like, self-healing plastics that combine the positive properties of thermoplastics and thermosets, are also conceivable. These are characterized by easy processing across a wide temperature range and exhibit dynamic epoxy-resin transesterification under the influence of heat. As such, they are repeatedly deformable, easily recyclable, and can be classified as "eco-friendly plastics." Furthermore, in terms of their deformability, vitrimers functionally bridge the gap between thermosets and elastomers. Alternatively, the starting material can also include vitrimer-like materials with thermally stimulated bond reversibility. These can be non-epoxy resin-based (possibly catalyst-free). Bioplastics such as polylactide vitrimers or vitrimers made from soybean oil and citrate are also conceivable. It should be noted that, in the case of a polymer or prepolymer as the starting material, the magnetocalorically excitable substance can be formed by the starting material itself. In other words, the starting material itself is magnetocalorically excitable. For example, semicrystalline polymers that sufficiently absorb electromagnetic radiation (RF), i.e., possess a relatively high dielectric loss factor, which can be increased as needed by one or more additives, are suitable; see, for example, US 2016 / 227876 A1. It should be noted that these polymers—which can be directly magnetocalorically excited—must also exhibit non-linear magnetization saturation behavior for the processing or manufacturing method proposed here. Therefore, a composition of the starting material independent of magnetocalorically excited particles is quite conceivable. The starting material can include one or more additives in addition to the magnetocalorically excitable substance. These additives can be organic and / or inorganic. Metals and ceramic materials, or their raw materials, can be used both as starting materials and as additives. Ceramic materials are characterized by their high hardness and temperature resistance, and can significantly increase the wear resistance and fire resistance of products. They are classified into oxides, carbides, and nitrides, primarily of the elements aluminum, tungsten, zirconium, silicon, and titanium. Phosphates (biocompatible) can also be used, as well as porcelains, quartz, lime, and clays. Ceramics are used in liquid form and as viscous resins, in the form of powders, granules, or filaments, and can be processed not only as spherical but also as stochastic particles of varying sizes and shapes. Metals are preferably used as starting materials in the form of spherical powders (e.g., 15–15 µm), in pure form and as individual alloys. Due to their very different properties, cross-contamination during production (e.g., atomization) must be avoided. Particularly in connection with use in magnetic fields, a distinction must be made between magnetic metals, e.g., stainless steel (in ferritic and martensitic microstructures), as well as cobalt, nickel, and iron, and non-magnetic metals. These include stainless steel (in austenitic microstructures), precious metals (gold, silver, bronze), as well as copper, titanium, and aluminum, and are particularly well suited for processing using the device or method according to the invention. According to the invention, the starting material can be in the form of a so-called "squid" (= preform). Such squids are otherwise preformed, incompletely cured polymer precursors. This allows the 3D structure to be produced in even less time. Alternatively, the starting material can also be used to produce such a "squid". In the case of a thermally decomposable starting material, this can also be in the form of one of the aforementioned polymers or as a metal. Additives in the starting material The potential of optional biological, chemical, physical, and pharmaceutical additives should not be underestimated. These can act as inducers, promoters, catalysts, and terminators of (bio)chemical reactivity, homogenizing and stabilizing the environment, and thus reducing artifacts. They can also increase or decrease electrical or thermal conductivity or insulation within the polymer precursor, thereby positively or negatively influencing polymerization / sintering or structural degradation of the starting material, protecting sensitive internal and external zones, and potentially simplifying post-processing. The additives can be used, particularly when the starting material is a prepolymer, especially from the group of: • fibers (e.g., carbon filaments, glass fibers) • dyes • antibacterial substances • growth factors • nanoparticles / tubes • mineral fillers (e.g., tricalcium phosphate cement, nano-hydroxyapatite, bioactive glass) • metallic materials (e.g., silver, gold, magnetite (Fe₂O₃, Fe₃O₄) - e.g., SPION = superparamagnetic iron oxide nanoparticles, Gd chelates / conjugates) • glycosaminoglycans • so-called MMC substances (for so-called macromolecular crowding; e.g., dextrans or Ficol (= sucrose-epichorhydrin copolymer)) • polypeptide motifs such as RGD sequences (arginine, glycine, and aspartic acid), which occur, for example, in proteins of the extracellular matrix (e.g., in fibronectin and vitronectin) • -IKVAV + - YIGSR (Laminin) and• promoters, terminators, inhibitors and catalysts,• sensitizers,• immunomodulators (such as VGF or the molecule JNK3). Magnetocaloric substance The term magnetocaloric substance encompasses all excitable chemical elements, substances, compounds, or chemical groups that can be excited by an alternating magnetic field with the release of heat. According to the invention, particles are suitable as magnetocaloric substances. This includes both microparticles with a maximum particle size between 1 µm and 1000 µm, determined by sieving, laser diffraction, or dynamic light analysis, and / or nanoparticles with a maximum particle size between 1 nm and 100 nm, determined, for example, by SEM microscopy, field-flow fractionation, or small-angle X-ray scattering. The nanoparticle concentration in the starting material is preferably less than 5 wt%, and the microparticle concentration in the starting material is preferably less than 15 wt%. Suitable particles include paramagnetic (nano)particles, ferromagnetic particles, ferromagnetic filaments and / or fibers, magnetosomes, magnetosome chains, synthetic or functionalized ceramic particles, carbon-based susceptors, and synthetic microspheres (carboxylated superparamagnetic microspheres, manufacturer: magnefy TM). The particles can consist of materials such as magnetite (Fe3O4) or a silver halide (AgnXn). The aforementioned magnetosomes contain nanoparticulate magnetite or greigite (Fe3S4) particles and are found in certain bacteria and fungi. These magnetosomes, produced by biomineralization, are characterized by a particularly small dispersion in the mean particle size of their nanoparticulate particles. Within the scope of the invention, such magnetosomes, preferably purified or optionally combined with the prokaryotic / eukaryotic cells in which the magnetosomes are contained, can be used as a magnetocalorically excitable substance. Although the known magnetosomes comprise nanoparticles made of a ferromagnetic material, the nanoparticles exhibit paramagnetic or superparamagnetic properties at a size of less than approximately 50 nm. See, for example, Manucci S et al (2018) Magnetosomes extracted from Magnetospirillum gryphiswaldensae as theranostic agents in an experimental model of glioblastoma.Contrast Media Mol Imaging Jul 11, 2018:2198703. doi: 10.1155 / 2018 / 2198703 . Heinke D et al (2017) MPS and MRI efficacy of magnetosomes from wild-type and mutant bacterial strains. Int J Mag Part Imag Vol 3 No 2 (2017), S. 1-6) Article ID 1706004. It should be noted that, in the case of a starting material comprising a prepolymer or a polymer, particularly a plastic polymer, the nanoparticles or microparticles can influence both the viscosity of the polymer and the material properties of the 3D structure to be produced from the starting material. Depending on the selection of particles used in the starting material, the mechanical strength, electrical conductivity, and / or resistance of the 3D structure to chemically or abrasively aggressive substances can be adjusted as required. The magnetocaloric substance is preferably homogeneously distributed within the starting material. Thus, in the case of a starting material designed as a prepolymer (i.e., a polymer precursor comprising one or more polymers, copolymers, and / or monomers and / or dimers, etc.), the magnetocaloric substance can be at least partially or completely bound to monomers / polymers.Such organometallic compounds typically exhibit a polar covalent bond between a carbon atom and at least one metal or electropositive element atom. However, it is also conceivable that the magnetocalorically excitable substance in the starting material is inhomogeneous, which means that in areas with a higher density of the magnetocaloric substance, as mentioned above, different material properties of the 3D structure to be produced can be set than in areas with a comparatively lower density of the magnetocaloric substance. The concentration of the magnetocalorically excitable substance or particles is preferably > 100 particles per milliliter of the starting material, and particularly > 10,000 particles per milliliter of the starting material. This ensures reliable and homogeneous polymerization / sintering / decomposition of the starting material during the processing / manufacturing process. The particle concentration can be adjusted according to the requirements of the 3D structure to be produced from the base material. According to the invention, the concentration of the magnetocalorically excitable particles can be up to 10¹⁷ particles per milliliter of the starting material. This allows even the smallest 3D structures to be additively manufactured with a previously unattainable level of detail resolution. It is understood that the starting material may also contain more than one magnetocalorically excitable substance, which differ at least partially in their material properties or in their specific chemical composition and / or size. With regard to the biocompatibility of the magnetocaloric substance and for the purpose of stabilizing its dispersion in the starting material, it can be coated, for example with titanium or another biocompatible material such as polyetheretherketone (PEEK), polyetherimide (PEI), polycarbonates, acrylonitrile butadiene styrene, polylactides (PLA), polyhydroxyacetic acid, polyglycolic acid. The thermogenicity of the magnetocalorically excitable substance used can be attributed to three main mechanisms, including the so-called Néel relaxation, the Brown relaxation and loss of hysteresis effects. Regarding the magnetoralorically excitable substance, the following laws apply: • the larger the particles, the greater their heating effect upon excitation; • the larger the particles, the lower the field strength required for saturation magnetization; • the larger the particles, the greater the alternating field amplitude required for magnetization reversal; • the larger the particles, the smaller the FFR; • the greater the magnetic field gradient, the smaller the FFR.• The higher the alternating field strength, the faster the temperature rise. • The higher the field frequency of the magnetic field used for excitation, the greater the heating effect of the particles with increasing hysteresis dominance. • In a magnetocaloric substance comprising nanoparticles, nanoparticle aggregation in the starting material can increase the heating effect (internal dipole interaction). • The larger the particles, the less superparamagnetic they are. • The larger the particles, the greater the Brown relaxation. • The larger the particles, the greater the hysteresis loss effects. • The smaller the particles, the greater the Néel relaxation. • The greater the distance of the particle from the FFR center, the lower its heating power. It should be noted that the influence of the shape, isomorphism, crystal structure and size of the magnetocaloric substance or magnetocaloric particles on their distribution quality, i.e. the tendency to migration and aggregation as well as their undesired movement in the magnetic field, decreases with increasing viscosity of the surrounding medium, i.e. the other starting material (e.g. resins) during rapid magnetic field switching. Alternating magnetic field The energy input into the field-free space of the starting material to be processed by means of the (frequency-modulated) alternating field can be influenced by the following factors: • Modulation of the amplitude of the magnetic alternating field (" = Excitation-Field"); • the location-specific excitation period of the magnetic alternating field defines the heat generation. Experimentally, a maximum of 2400 W / g could be achieved (using magnetospirillum as the magnetocaloric substance; at a field frequency of 200 kHz and a magnetic flux density of 38 mT) (= 300 × 10⁵ - 6 × 10⁶ times the FDA limit for diagnostic energy transfer by electromagnetic fields to human tissue. This corresponds to 573 °C / g s). Using magnetosome chains (d: 20 / 23 nm; I: 140 nm; 300 kHz) and a magnetic flux density of 15 mT, more than 1250 W / g could be achieved. In this regard, reference is made to the publication "Application of Magnetosomes in Magnetic Hyperthermia" by Nikolai A. Usov 1,2,3,* and Elizaveta M. Gubanova 3. Nanomaterials. Nanomaterials 2020, 10, 1320; doi:10.3390 / nano10071320. Resolving power The resolving power of the device or manufacturing process is directly dependent on the spatial extent of the field-free space. Theoretical influencing factors include: • FWHM / gradient strength (T / m) (FWHM in the derivative of the Langevin function assumed as the characteristic curve of the saturation magnetization) • Gradient strength (possibly nonlinearity) • Field dynamics (c TWMPI; rotation) • Additional fields (saturation, cancellation) • Nonlinearity of the particle saturation magnetization • Size, shape, surface, crystallization, aggregation state, shell Generally, the heating power of the magnetocalorically excitable substance or particles decreases increasingly sharply outside the FFR. This creates a small offset field around the FFR, which can be considered the "penumbra" of the FFR. While a reduction in detail resolution during the fabrication of the 3D structure is due to blurring of the polymerization boundaries, which occurs as a result of thermodynamic heat conduction exceeding the FFR during manufacturing, macrodimensional aberrations based on coarse heat accumulation primarily become apparent only after the end of polymerization / sintering or decomposition of the starting material, resulting in shrinkage and warpage due to material relaxation during cooling. Experience has shown that these phenomena are less pronounced with inductive heating than with other thermal curing processes and can be further reduced by preheating the starting material and, if necessary, post-heating the 3D structure. Against this background, the device can include a temperature control unit for maintaining the temperature of the working area or the starting material to be arranged / arranged within the working area. The temperature control unit can be used to cool the polymer precursor as needed, for example, to counteract undesirable, uncontrolled polymerization of the starting material outside the field-free space before and / or during the production of the 3D structure. The temperature control unit can also be used to heat the working area or the starting material arranged within it, i.e., to "temper" it, if necessary, to facilitate its processing. Tempering—that is, preheating—the starting material serves both to mitigate temperature gradients and homogenize the temperature profile in general, and specifically to reduce the amount of energy to be applied inductively, thus reducing the risk of aberrant thermal dynamics at the micro and macro levels. This can be understood as preconditioning the starting material. The clearer and more precisely defined the transition threshold, the more precise the manufacturing process. Furthermore, the lower the thermal conductivity of the starting material, the lower the risk of heterotopic heat accumulation and thus dystopic polymerization / sintering / decomposition of the starting material; consequently, the higher the thermal and structural resolution. To avoid both macro- and micro-dimensional heat accumulation, the generation of large solidity and volume differences, concentrated material masses, sharp caliber jumps, and significant temperature differences in the 3D structure to be produced should be avoided. On the other hand, the resolving power of the starting material increases with the steepness of the temperature gradient between heated FFRs relative to their surroundings. Therefore, cooling measures should even be considered at relevant interfaces, functional reliefs, and edge edges to optimize detail. A certain degree of stimulation redundancy in the magnetocaloric substance or inertia in the polymerization / sintering / decomposition of the starting material can also reduce the susceptibility to thermal artifacts in favor of structural resolution.In the multi-shot concept, several stimulative alternating magnetic field pulses are necessary to reach the transition temperature, strictly tailored to the thermal conductivity of the starting material, resulting in a steeper temperature gradient to the respective volume areas of the starting material adjacent to the FFR and thus a higher separation efficiency. As the polymer / sintered starting material cures, its structural properties change, significantly impacting heat dissipation. Due to zonally varying material continuity and solidification, an increasingly heterogeneous thermal system develops with progressive curing. Cumulative effects create a coexistence of overheated and undercooled zones, which should be prospectively factored in and proactively compensated to minimize dystopic polymerization / sintering / decomposition. This can be achieved by considering all described phenomena and influencing factors, firstly by selecting a suitable thermoresponsive starting material with an appropriate thermal transition threshold and advantageous thermal conductivity (so), and secondly, by precisely modulating the pulse duration and intervals of the excitation alternating magnetic field.Thus, a longer continuous local excitation leads to a steeper temperature gradient than a repetitively repeated short, impulsive excitation, and the sequential excitation of two immediately adjacent volumes of the starting material leads in total to a locally higher heat accumulation than the stimulation of two volumes located far apart. According to the invention, the working area of ​​the device can be arranged within an enclosure or housing. This allows a defined working environment for generating the 3D structure to be provided and maintained. For example, the temperature, atmospheric composition (working atmosphere), atmospheric pressure in the working area, and humidity of the atmosphere immediately surrounding the working area can be easily and cost-effectively adjusted as needed. The enclosure can be made of plastic, for example, in the form of a plastic film, glass, or another suitable material. The temperature control unit can also be used, in particular, for the controlled cooling of the starting material / 3D structure. For this purpose, cold air and / or a suitable cooling liquid, such as water, can be supplied to the starting material / 3D structure via the temperature control unit. This helps to prevent the formation of undesirable damage, especially stress cracks, in the 3D structure. The device preferably includes a pump by means of which the working area can be filled with a working atmosphere specified for the respective manufacturing process, or a sub-atmospheric pressure or an approximate vacuum can be established in the working area. This also enables surface smoothing of the 3D structure, for example by vapors (so-called "vapor smoothing"), or disinfection / sterilization of the 3D structure directly in the working area. 3D structure The 3D structure that can be produced using the device can be any product. For example, the 3D structure could be a machine element. This includes, in particular, axles, shafts, bearing elements, gear parts, sealing elements, connecting elements, housings (or housing components), etc. The 3D structure could also be an adhesive, soldered, or welded joint between two or more components, or a coating on a component. The 3D structure to be produced from the starting material could, for example, consist of an elastomer, a thermoplastic, or a thermosetting polymer, or comprise one of these materials. The 3D structure can also be a medical device, for example, an epithesis, an orthosis, a bandage, a dental brace, a dental veneer, a breathing tube, a tissue adhesive, a medical implant, or even a (bio-)artificial structure for tissue or organ replacement. Furthermore, the 3D structure can be an everyday object, such as jewelry, a watch case, a toy, a carrying container, dishes, or cutlery. The conceivable in-situ processing of the starting material, comprising or resulting from metallic, ceramic, and / or plastic polymers, to produce a 3D structure is feasible. This would allow all the advantages of natural tissue regeneration within a physiological, bioresponsive environment to be fully exploited from the outset. Cardinal problems of conventional tissue replacement products and bioreactors, such as insufficient stability, lack of integrativity, lack of adaptivity, lack of interactivity, and inadequate viability, could be overcome. The device according to the invention holds the key to universality and the enormous potential to produce a 3D structure that is highly flexible and individualized at both the microtopographical and macroarchitectural levels, addressing the diversity of tissue defects and recipients requiring therapy. Using the device, a 3D structure can be produced that authentically replicates the natural anisotropy of hierarchically organized biological tissues and the deterministic complexity of bioartificial interfaces, in order to establish the biomimetic foundations for long-term functionality of the implant within the overall systemic network at the earliest possible stage and sustainably. For example, the device or system according to the invention can be used in the in-vivo production of the 3D structure. Here, a seamless integration of the 3D structure to be produced with endogenous or exogenous structures is possible.whose anchoring at the target site with the surrounding tissue is achieved. This allows the device to enable direct in-situ 3D bioprinting in living organisms. The optional vitalization of the 3D structure through passive and / or active cell seeding can be achieved, for example, contactlessly and minimally invasively. If the device incorporates at least one or more of the aforementioned image (data) acquisition features, it enables image-controlled or image-navigated application of the starting material to the predetermined target location. This is particularly advantageous for the in-vivo fabrication of the 3D structure. It should be noted that, when used in the broader medical field, the device according to the invention enables 8D fabrication of the 3D structure. This is a technology that can "add" material in all spatial directions without regard to axes ("real" 3D). During in-vivo fabrication, the 3D structure can interact with its environment (4D), instruct it (5D), be vitalized by cells (6D), and thus be adaptable until complete biological integration (7D). Furthermore, it can also be modified externally without contact and, if necessary, multiple times (8D).It is particularly noteworthy that the “real” 3D processing ensures a homogeneous isotropic – i.e., uniform – load-bearing capacity of the 3D structure, whereas classic 3D printed products usually exhibit a direction-dependent mechanical load-bearing capacity depending on the traditional build axis (z-axis). In a medical context, the device or 3D method according to the invention can be used to repair, reconstruct, respect, correct, and optimize the integrity and interactivity of functional anatomical structures in order to stimulate and amplify authentic regenerative processes. This applies in particular to very small anatomical functional units and very large tissue volumes, which have so far defied sufficient restoration using conventional techniques. Since electromagnetic induction, unlike established traditional methods of contactless energy transfer (UV, IR, ultrasound, LASER), does not exhibit relevant undesirable interference and absorption phenomena with increasing travel distance (penetration depth) or at tissue interfaces, and, provided legal dose limits and frequency spectra are observed, has no biologically harmful potential, and does not require a protective atmosphere or rigid, mechanical guidance systems, it can be considered an ideal energy transmitter for contactless 3D manufacturing, especially in in-situ biofabrication. The inventive method for generating a 3D structure by processing a starting material using the aforementioned system can be referred to as Magneto Selective Manufacturing (MSM). The method comprises the following steps: a. Defining (102) CAD / CAM data (40) for the 3D structure (30) to be manufactured; b. Providing (104) a starting material to be processed, which comprises a magnetocalorically excitable substance distributed within the starting material, preferably homogeneously; c. Introducing (106) the starting material into the working area of ​​the device (12); d. Position encoding (108) of a first field-free region within the starting material as a function of the CAD / CAM data (40) by applying at least one gradient field; e.Magnetocaloric excitation of the substance in the field-free region by superimposing an alternating magnetic field, such that the starting material, preferably alone, is thermally induced to polymerize or sinter in the field-free region or is thermally structurally decomposed. The starting material arranged in the FFR is thus heated by irradiation with the alternating magnetic field and the associated magnetocaloric excitation of the substance, and thereby polymerized in the case of a starting material that is formed as a prepolymer; sintered as a metallic or ceramic starting material; or thermally decomposed in the case of a polymer material or a metallic starting material. The additive / subtractive manufacturing process proposed here allows the 3D fabrication of any 3D structure of any geometry, configuration, and complexity—depending on the starting material used, even of any consistency—individually in vitro and, if necessary, also in vivo. The strategy of building structures from the smallest possible subunits results in maximum design freedom and adaptability of the process. This is achieved with unprecedented detail and speed. The process can open up new avenues for the fabrication of machine elements, medical products, in medical and biotechnological biofabrication, and even in in-situ bioprinting. This is particularly true because the MSM process according to the invention enables precise surface design and seamless integration or anchoring with other structures. This allows for simplified and more reliable revitalization through passive / active cell colonization following implantation of the 3D structure. In a medical context, the MSM proposed here can enable the creation of implants that repair, reconstruct, respect, correct, and optimize the integrity and interactivity of functional anatomical structures in order to stimulate and amplify natural regenerative processes. Unlike established traditional methods of contactless energy transfer using UV / IR radiation, ultrasound, or lasers, electromagnetic induction does not exhibit relevant undesirable interference and absorption phenomena, either with increasing distance traveled in the polymer precursor or tissue (penetration depth) or at material interfaces. Furthermore, electromagnetic induction, when adhering to legal dose limits and frequency spectra, has no biologically harmful potential, inherently requires no protective atmosphere or rigid mechanical guidance systems, and is therefore considered an ideal energy transmitter for contactless in vitro and in vivo biofabrication. The MSM method according to the invention now offers for the first time a practical approach to how inductive energy deposition can be realized, modulated and specifically used for controlled additive and subtractive structure building by means of non-directional alternating electromagnetic fields (RF field). The special appeal of the method according to the invention lies in the subtle, multi-parametric controllability of the step-by-step assembly phases of the product structure in real time, resulting in maximum process control, individualizability and result quality. To process the starting material in different spatial regions, the method according to the invention comprises the following further steps: f. spatial encoding of a further, field-free region in the starting material depending on the CAD / CAM data of the 3D structure to be produced by means of the gradient field; and g. magnetocaloric excitation of the magnetocalorically excitable substance in the further field-free region by superimposing an alternating field, such that the remaining starting material in the field-free region is thermally induced to polymerize or sinter or is thermally structurally decomposed. According to the invention, the spatial encoding of the further field-free region can be achieved by moving the starting material and the gradient field relative to each other using a mechanical adjustment device of the system, or by superimposing the gradient field with one or more further magnetic fields, preferably each in the form of a homogeneous magnetic field. Advantageously, the relative movement can be performed along / around all three spatial axes X, Y, Z. According to the invention, the size and / or geometry of the respective field-free region can be defined, i.e., predetermined, depending on the CAD / CAM data of the 3D structure to be produced by superimposing the gradient field with one or more further inhomogeneous magnetic fields. These magnetic fields can be referred to as zoom or focus fields. This can accelerate the manufacturing of the 3D structure and, if necessary, counteract the formation of stress damage. Particularly high dimensional accuracy of the 3D structure to be produced can be achieved by acquiring image data of the starting material and / or the partially produced 3D structure, preferably at intervals, using an imaging device of the apparatus, and by carrying out the further manufacturing process taking this image data into account, whereby, if necessary, the further steps include comparing the image data with the CAD / CAM data; and changing the CAD / CAM data for the 3D structure based on the image data if a deviation of the image data from the CAD / CAM data, defined as the maximum permissible deviation, is exceeded. According to the invention, the frequency / phase / amplitude of the alternating magnetic field is / is tuned to the characteristic optimal frequency for the desired / suitable thermal output of the magnetocalorically excitable substance to be excited and the viscosity of the starting material of a respective addressed VOI or FFR under given magnetic saturation conditions outside the FFR. If the device is configured for MPI imaging, the viscosity of the starting material can simultaneously be determined in real time using the color MPI method. The intervals between the magnetic alternating field irradiations (e.g., RF pulse (pulse periodicity)) are defined according to the invention as a function of the following factors: • Thermogenicity (= characteristic power input + thermal efficiency) of each individual oscillator or their thermogenic sum / voxel. • Thermal transition threshold(s) of the polymer precursor or mineraloids / ceramics or metals. • Thermal conductivity of the polymer, mineraloid, or metal or its precursors. • Polymerization kinetics or sintering kinetics or decomposition kinetics (material-specific / architecture-specific). • Polymerization pattern or sintering pattern or decomposition pattern (see CAD); e.g., resolution, thermal bridges / accumulating subunits. • Spatial pulse density. • Temporal pulse density (= modulation of the energy input via temporospatial pulse algorithms). • Optionally, pulse amplitude / irradiation angle with respect to the voxel to be excited. The interval periodicity or pulse-train length of the alternating field (or RF) stimulation is primarily defined by the thermodynamic effects in the given setting and may be limited by the maximum speed of the control unit + magnetic field generators to switch between 2 precise 3D-FFR voxel isolations ("indirect focusing"). According to the invention: • In principle, almost any interval can lie between the individual pulses of the RF radiation, provided that the voxel-specific or VOI-specific (volume of interest) energy input, individually or as a sum, produces the desired thermal effect in the voxel / VOI; • With maximally fast voxel (or VOI) resonance isolation (target coding), continuous RF radiation (RF pulsation) is theoretically also possible, since only those oscillators for which suitable saturation conditions prevail thermogenically; • With in-vivo fabrication of the 3D structure, a fractional pulse algorithm, e.g., with repetitive RF radiation cycles, is possible, which is advantageous from a thermodynamic perspective and enables a minimization of the global RF and thus energy irradiation into biological tissue. According to the invention, the frequency of the RF radiation radiated into the working area can, in principle, be in the kilohertz to terahertz range. The frequency of the RF radiation radiated into the working area can, in principle, be between 1 kHz and 1 GHz, preferably between 10 kHz and 1 MHz, and most preferably between 100 kHz and 500 kHz. The device's control unit serves the following tasks: a. Plant control / monitoring b. Data management c. CAD unit d. Image acquisition / analysis / reconstruction It goes without saying that the control unit may have application software with AI features. The inventive method can include a further post-treatment step of the 3D structure after printing. The entire 3D structure can be maintained at a predetermined temperature for a defined period and / or cooled in a predetermined manner, particularly in stages. In the former case, any necessary "maturation" of the 3D polymer structure, i.e., complete polymerization of the entire 3D structure, particularly after removal of excess prepolymer, can be achieved. The heat input required for this can be achieved, for example, without prior spatial encoding of individual voxels, by irradiating the 3D structure with RF radiation or by applying infrared radiation and / or supplying hot air. To cool the entire 3D structure, the aforementioned active heat input into the 3D structure can be reduced gradually over time, or the 3D structure can be cooled in a controlled manner by active heat removal, such as the introduction of a cooling medium (e.g., air or water). This prevents undesirable stress cracks and similar defects in the 3D structure. Use of the device / system The device, system, or starting material described above, containing the magnetocalorically excitable substance, can be used universally in the fields of engineering and medicine. For example, it can be used to produce medical implants, particularly bone replacements, scaffolds for organs or tissues, or vascular prostheses. The following are some possible uses of the invention: Plastic Radiology: • Stabilization of tissue / creation of placeholders • Reconstruction of tissue / replacement of tissue • Adaptation / anchoring / embolization • Augmentation / contouring / enhancement of tissue • Compartmentalization / encapsulation, e.g. of pathological processes. Reparative & Reconstructive Radiology: In addition to the specific replacement of connective and supporting tissues (cartilage, bone, tendons, ligaments, intervertebral discs), the device / system is suitable for plastic reconstruction, functional and aesthetic shaping and correction, as well as diffuse tissue stabilization in cases of primary and secondary reduced tissue tone. The device / system can be used to create a 3D structure: • as a binding agent in fracture zones and arthrodesis; • as an adhesive for the treatment of acute wounds and as a bioactive protector for chronic wounds; • as a mesh replacement in hernioplasty and as a spacer; • as a guiding structure and carrier material for cellular structures and / or acellular additives and active ingredients. Furthermore, the invention allows for the synthesis, anastomosis, stabilization, adaptation, and occlusion of cavities in vivo, including valve, sphincter, and shunt systems, largely independent of their dimensions, configuration, and location. This promises, for the first time, individualized curative strategies for a multitude of chronic diseases that have previously been only partially treatable, such as peripheral arterial disease (PAD), lymphedema, and chronic venous insufficiency, and should also significantly improve the outcome of classic (microvascular) flap procedures and acral replantations. The invention can be used for a gentler yet more efficient anchoring of an implant, particularly a joint endoprosthesis. When the endoprosthesis wears out, the device and the polymer precursor can be used in vivo to recoat it. The invention can also be used to create a large-area or full-surface bioartificial cartilage replacement in situ. Captive Radiology: The device / system / polymer precursor can be used for hazard prevention and complication control of tumorous and inflammatory diseases by isolating affected anatomical compartments using the 3D structure. This allows such pathological processes to be treated – or palliatively contained – in an isolated “neoanatomical” space, for example, with chemotherapy, immunotherapy, radio-oncology, or thermal therapy. Since the probability of metastasis increases with increasing tumor surface area, even incomplete encapsulation of tumors using the in vivo generated 3D structure is likely to offer a prognostic benefit. Furthermore, the artificial polymeric encapsulation can serve as a guide for biopsies, as an aid during tumor surgical resection, as a solidified safety margin, and more generally as a spacer or protective shield for vulnerable structures. Manual radiology: The device / system or polymer precursor can be used in the in-vivo production of 3D structures in the form of guide elements, anatomical (e.g., electroconductive) guide wires, and polymeric 3D rail networks, as well as bioartificial sensor technologies and conductor systems. This can further advance the emerging automation of medical therapy and diagnostics, for example, through intracorporeally deployed (semi-)autonomous miniature robots, soft robots, or, in particular, intracorporeally wearable electronic devices. During the manufacturing process, at least some of the voxels / volumes of interest defined based on the CAD / CAM data can be modified in their spatial position within the work area, their size, and / or their geometry using image data acquired, particularly magnetic resonance imaging (MRI). This allows for further improvement of the manufacturing tolerance of the 3D structure. Depending on the imaging unit used, the manufacturing process does not need to be interrupted to acquire suitable image data from the work area, particularly from the starting material or the already created 3D structure (or the environment adjacent to the 3D structure). The image data can be acquired specifically based on the CAD / CAM data of the 3D structure to be manufactured. According to the invention, the image data are preferably compared with the CAD / CAM data, and if a deviation is detected in the already (partially) manufactured 3D structure, the CAD / CAM data for generating the remaining 3D structure is modified based on the image data. This allows for an exceptionally small manufacturing tolerance of the 3D structure. Further advantages of the invention will become apparent from the description and the drawing. The embodiments shown and described are not to be understood as an exhaustive list, but rather serve as examples for illustrating the invention. Detailed description of the invention and drawing Fig. 1 shows the schematic setup of a system according to the invention, comprising a device and a starting material that can be arranged in the working area of ​​the device, from which a predetermined 3D structure is to be produced; Fig. 2 shows the starting material in the gradient field of the device, showing a point-like field-free space in the starting material; Fig. 3 shows the starting material in the gradient field of the device, showing a line-like field-free space in the starting material; Fig. 4 shows an enclosure within which the starting material is arranged during the 3D manufacturing process; and Fig. 5 shows a block diagram of the method according to the invention for generating a 3D structure with individual process steps. Fig. 1 shows a system 10 for manufacturing a 3D structure 12 by processing a starting material 14 comprising a magnetocalorically excitable substance based on CAD / CAM data of the 3D structure 12. The system 10 comprises a device 16 with a working area 18 for receiving the starting material 14. A gradient field generator 20 serves to generate a gradient field, preferably one that can be modulated. The design of the gradient field generator 20 can be tubular, as shown in Fig. 1, so that the starting material 14 to be processed can be inserted into the working area 18 of the device 16 from the end face, and the resulting 3D structure 12 can be removed from the working area 18 of the device 16 from the end face. Alternatively, the gradient field generator 20 can also have an open design to allow lateral access to the working area. The field strength of the magnetic gradient field is orders of magnitude greater than the Earth's magnetic field. It should be noted that the gradient field can be variably changed spatially with respect to its field direction and / or temporally with respect to its field strength. The device 16 additionally comprises at least one frequency- or amplitude-modulated alternating field generator 22 for radiating a frequency-modulated alternating magnetic field (RF field) into the working area 18. The alternating field generator 22 serves to supply the energy required for the three-dimensionally spatially encoded processing of the starting material 14 into the working area 18. The gradient field generator 20 serves to create a field-free space (= FFR) at a defined position (VOI) within the starting material 14 arranged in the working area 18 and to magnetically saturate the magnetocalorically excitable substance of the starting material 14 outside the respective FFR. As a result, only, or essentially only, the magnetocaloric substance of the starting material 14 located within the FFR can be magnetocalorically excited by the alternating magnetic field emitted by the alternating field generator 22. The device 16 further comprises several, here three, magnetic field generators 24a, 24b, 24c, by means of which a homogeneous magnetic field B1, B2, B3 can be superimposed on the gradient field in the working area in the direction of the three spatial axes X, Y, Z. The field-free space FFR generated by the gradient field generator 20 can be moved along all three spatial directions X, Y, Z relative to the working area 18 and thus to the starting material 14 to be processed by (controlled) superposition of the aforementioned homogeneous magnetic fields B1, B2, B3. Alternatively or additionally, the device 16 can have a mechanical movement device 26 to mechanically adjust the working area 18, including the starting material 14 arranged therein, and the gradient field, preferably multi-axis, relative to each other. This allows a different VOI of the starting material 14 to be detected and processed by the FFR. A control unit 28 with a computer system 30, a memory 32 containing stored CAD / CAM data 34 for the 3D structure 12 to be manufactured, as well as an input and operating console 36a and a display 36b, serves to control all operating parameters of the device 16. The device can also be a... In Figs. 2 and 3, the starting material 14 is shown in the gradient field 38 of the device. The FFR 40 defined by the gradient field 38 is native, i.e., without superposition of further magnetic fields, point-like according to Fig. 2 and can be line-like by superposition of two gradient fields 38 according to Fig. 3. By appropriately superimposing one, two or three inhomogeneous magnetic fields G1, G2, G3 that can be generated by means of the magnetic field generators 25a, 25b, 25c, the FFR can be varied in its geometry and size on the basis of the CAD / CAM data of the 3D structure in a manner suitable for the manufacture of the 3D structure 12. The starting material 14 can, for example, be a prepolymer 14a. The prepolymer 14a can consist of identical or different monomers, dimers, oligomers, or polymers. Furthermore, the prepolymer can include fibers and / or one or more other additives. Depending on the mechanical, electrical, or biological requirements of the 3D structure, the prepolymer can, for example, have a viscosity of approximately 102 mPa·s to 105 mPa·s or higher. The starting material 14 can also be a powdered or granulated metal 14b, a powdered or granulated ceramic material (= ceramic precursor) 14c, or a reformling 14d. A preformling is understood to be a 3D shaped body made of a polymer material or a 3D shaped body made of a metal or ceramic material, possibly only partially polymerized. The magnetocalorically excitable substance 42 can be in the form of particles, such as nano- or microparticulate metal particles (=nano-oscillators). The metal particles can consist, in particular, of nanoparticulate magnetite (Fe3O4). In the gradient field, the maximum possible magnetization of the magnetocaloric substance 42 is reached outside the FFR. There, the magnetocaloric substance 42 undergoes magnetic saturation. The magnetocaloric substance is preferably homogeneously distributed in the starting material 14. The magnetocaloric substance 42, located in the FFR 40 of the gradient field 38, can be excited by the alternating magnetic field 44 generated by the frequency-modulated alternating field generator 22. Upon excitation of the magnetocaloric substance 42, its thermogenicity is essentially attributable to three main mechanisms, including Néel relaxation, Brown relaxation, and hysteresis loss effects. The control unit 28 or the computer system 30 of the device 16 is programmed to control the frequency-modulated alternating field generator 22 in such a way that the magnetocalorically excitable substance 42 of the starting material 14 can be excited in the field-free space spatially encoded by the gradient field 38 by means of the alternating magnetic field 44 generated by the alternating field generator 22, such that, in the case of a starting material 14 comprising a prepolymer, a thermally induced polymerization of the prepolymer to a polymer is triggered; and / or in the case of a starting material comprising a ceramic material and / or a metallic material, a sintering of the ceramic / metallic material is triggered; or in the case of a starting material designed as a preform, a thermal structural decomposition of the starting material is triggered, preferably exclusively, in the defined field-free space FFR 40. It is understood that the energy input of the alternating field 44 required for the thermally induced polymerization / sintering or structural decomposition of the starting material 14 for the magnetocaloric excitation of the magnetocalorically excitable substance 42 in the starting material 14 arranged in the field-free space must be specifically tailored to the material properties of the starting material 14 and the magnetocaloric substance 42 contained in the starting material 14. This must be determined experimentally, and the alternating field 44 must be defined accordingly with respect to its amplitude, frequency, and pulse duration. The experimentally obtained data are advantageously stored in the memory 32 of the control unit 28. The field frequency of the alternating magnetic field 44 for exciting the magnetocalorically excitable substance 42 is in any case between 1 kHz and 1 GHz, preferably between 10 kHz and 1 MHz, and most preferably between 100 kHz and 500 kHz.The device 16 preferably comprises an imaging unit 46 for acquiring image data from the working area 18. The imaging unit can comprise an MRI scanner, a computed tomography scanner, a CCD camera, or an infrared camera, wherein the control unit 28 is configured to compare this image data with the CAD / CAM data 34 of the 3D structure 12 and, upon detection of deviations, particularly geometric ones, between image data and CAD / CAM data 34, to take the image data or the deviations into account in the further manufacturing process, wherein the control unit 28 is configured to modify the CAD / CAM data 34 based on the (acquired) image data. In the latter case, the use of artificial intelligence or...a software application with AI capability stored in the control unit may be advantageous, especially since systematic deviations detected in the manufacturing process during the creation / modification of the CAD / CAM data 34 for the relevant 3D structure 12 and / or the manufacturing process can be prospectively taken into account. The working area 18 of the device can be delimited by means of an enclosure 48, preferably gas-tight, as shown in Fig. 4. The enclosure 48 can, for example, be made of plastic, glass, or another material that does not shield against RF fields or magnetic fields. The enclosure 48 can, for example, be formed by a plastic film in which the starting material 14 is arranged. A pump 50 (Fig. 1) can be assigned to the working area of ​​the device 12, by means of which the atmosphere within the enclosure 48 can be evacuated or substantially evacuated and / or via which the working area 18 within the enclosure 48 can be filled with a fluid specified for the manufacturing process, in particular a defined working atmosphere. In this way, for example, undesirable oxidative processes of the starting material 14 by oxygen can be counteracted or a so-called surface vapor smoothing of the 3D structure can be achieved. System 10 is universally suitable for the production of any, especially smaller, 3D structures 12, particularly those with complex geometry, and can be used, for example, to produce machine elements, consumer goods, and medical implants. The method 100 for generating the 3D structure 12 is explained in more detail below with additional reference to the block diagram shown in Fig. 5. The method 100 for manufacturing the 3D structure 12 (Fig. 1) necessarily requires the use of the system 10 described above in the context of Fig. 1, Fig. 2, Fig. 3 to Fig. 4 with the device 12 and with the starting material to be processed. The method comprises the following steps: a. Defining 102 CAD / CAM data 34 for the 3D structure 12 to be manufactured; b. Providing 104 a starting material 14 to be processed, which comprises a magnetocalorically excitable substance 42 distributed, preferably homogeneously, within the starting material 14; c. Introducing 106 the starting material 14 into the working area 18 of the device 16; d. Three-dimensional position encoding 108 of a first field-free region 40 within the starting material 14 as a function of the CAD / CAM data 34 by applying at least one gradient field 38; e. Magnetocaloric excitation 110 of the substance 42 in the field-free region 40 by means of an alternating magnetic field 44, such that the starting material 14, preferably alone, is thermally induced to polymerize or sinter in the field-free region 40 or is thermally structurally decomposed. To process a different spatial position, i.e., a different Volume of Interest (VOI) 60 of the starting material 14 (see Fig. 2), a further step 112 involves the three-dimensional spatial encoding 112 of another field-free region 40 in the starting material 14, depending on the CAD / CAM data 34 of the 3D structure 12 to be generated, by means of the gradient field 38, by a relative movement 114 of the starting material 14 and the gradient field 38 relative to each other by means of the mechanical motion device 26 of the apparatus 16. Alternatively, this can be achieved by superimposing 116 the gradient field 38 with one or more further homogeneous magnetic fields B1, B2, B3, such that the field-free space 40 and the further VOI 60 of the starting material 14 to be processed coincide spatially. In step 118, the magnetocalorically excitable substance 42 is magnetocalorically excited in the field-free region 40 of the gradient field 38, such that the starting material 14 is thermally polymerized or sintered in the field-free region 40, or thermally structurally decomposed. Steps 112 to 118 are repeated as needed until the 3D structure specified by the CAD / CAM data is generated from the starting material. The size L and / or geometry G of the respective field-free space FFR 40 can be varied depending on the CAD / CAM data (34) by superimposing the gradient field 38 with another, preferably inhomogeneous, magnetic field G1, G2, G3 or by means of several other, preferably inhomogeneous, magnetic fields G1, G2, G3. This is done, for example, in the optional step 122. In optional step 120, image data 70 can be acquired at any time for the starting material 14 and / or the (partially) generated 3D structure 12, and the further manufacturing process of the 3D structure 12 can be continued taking the respective image data 70 into account. The image data 70 can be compared with the CAD / CAM data 34 by means of the control unit, and the CAD / CAM data 34 can be modified by means of the control unit if a maximum permissible deviation of the image data 70 from the CAD / CAM data 34 is exceeded. This allows for further improved dimensional accuracy of the 3D structure 12 to be manufactured.

Claims

Device (16) for manufacturing a 3D structure (12) from a starting material (14) with a magnetocalorically excitable substance (42), based on CAD / CAM data (34) for the 3D structure (12), comprising: • a working area (18) for receiving the starting material (14) to be processed; • a control unit (28) with a memory (32) for the CAD / CAM data (34) of the 3D structure (12) to be produced; • a gradient field generator (20) for generating a gradient field (38) by which a defined field-free space (40) in the starting material (14) arranged in the working area (18) can be spatially encoded and by which the magnetocalorically excitable substance in the starting material outside the field-free space (40) is positively or negatively magnetically saturated; and• an alternating field generator (22) for radiating a frequency- and amplitude-modulated alternating field (44) into the working area (18);wherein the control unit (28) is configured to control the alternating field generator (22) such that the magnetocalorically excitable substance (42) of the starting material (14) can be excited in the spatially coded field-free space (40) by means of the alternating field (44) in order to: • in the case of a starting material (14) comprising a prepolymer (14a) thermally induced polymerization of the prepolymer (14a) to a polymer; and / or • in the case of a starting material (14) comprising a ceramic material (14b) and / or a metallic material (14c) sintering of the ceramic / metallic material; or • or thermal structural decomposition of the starting material (14), preferably alone, induce in the defined field-free space (40). Device (16) according to claim 1, characterized in that the device (16) for spatial repositioning of the defined field-free space (40) relative to the working area (18) / starting material (14) comprises a mechanical movement device (26) by means of which a mechanical relative movement of the working area (18) / starting material (14) and the gradient field (38) can be generated and / or that the device (16) has one or more magnetic field generators (24a, 24b, 24c) for generating one or more homogeneous magnetic fields in the working area which can be superimposed on the gradient field (38) in order to move the defined field-free space (40) relative to the working area (18) / starting material (14). Device (16) according to claim 1 or 2, characterized in that the device (16) has one or more magnetic field generators (24a, 24b, 24c) for generating one or more inhomogeneous magnetic fields G1, G2, G3..G(n) in the working area (18), which can be superimposed on the gradient field (38) in order to change the defined field-free space (40) in its geometry and / or size, in particular on the basis of the CAD / CAM data (34). Device (16) according to one of the preceding claims 1 to 3, characterized in that the device (16) has an imaging unit (46) for obtaining image data (70) from the working area (18), wherein the control unit (28) is preferably configured to compare the image data (70) with the CAD / CAM data (34) of the 3D structure (12) and, if deviations, in particular geometric ones, between image data (70) and CAD / CAM data (34) are detected, to take the image data (70) or the deviations into account in the further manufacturing process of the 3D structure (12) and / or that the control unit (28) is configured to modify the CAD / CAM data (34) on the basis of the image data (70). Device (16) according to one of the preceding claims, characterized in that the field frequency of the alternating field (44) is between 1 kHz and 1 GHz, preferably between 10 kHz and 1 MHz, most preferably between 100 kHz and 500 kHz. System (10) for manufacturing a 3D structure (12) from a starting material (14) with a magnetocalorically excitable substance (42) based on CAD / CAM data (34) of the 3D structure (12), comprising a device (16) according to one of the preceding claims 1 to 5 and the starting material (14) with the magnetocalorically excitable substance (42). Method (100) for manufacturing a 3D structure (30) using a system (10) according to claim 6, comprising the following steps: a. Defining (102) CAD / CAM data (34) for the 3D structure (30) to be manufactured; b. Providing (104) a starting material to be processed, comprising a magnetocalorically excitable substance (42) distributed, preferably homogeneously, within the starting material; c. Introducing (106) the starting material into the working area of ​​the device (12); d. Position encoding (108) a first field-free space (40) within the starting material (14) by applying at least one gradient field (38), wherein the magnetocalorically excitable substance in the starting material outside the field-free space (40) is positively or negatively magnetically saturated; e.Magnetocaloric excitation (110) of the substance (42) in the field-free space (40) by irradiation with an alternating magnetic field (44), such that the starting material (14), preferably alone, is thermally induced to polymerize or sinter in the field-free space (40) or is thermally structurally decomposed. Method (100) according to claim 7, characterized by the further steps: • Position encoding (112) of a further field-free space in the starting material (14) depending on the CAD / CAM data (34) of the 3D structure (12) to be produced by means of the gradient field (38); and • Magnetocaloric excitation (118) of the magnetocalorically excitable substance (42) in the further field-free space by the alternating field (44), such that the starting material (14) in the field-free space is thermally induced to polymerize or sinter or is thermally structurally decomposed. Method (100) according to claim 8, characterized in that, for position encoding (112) of the further field-free space, the starting material (14) and the gradient field (38) are moved relative to each other by means of a mechanical movement device (26) of the device (16); or the gradient field (38) is superimposed with one or more further, preferably homogeneous, magnetic fields B1, B2, B3. Method (100) according to one of claims 7 to 9, characterized by defining the size and / or geometry of the respective field-free space depending on the CAD / CAM data (34) by superimposing the gradient field (38) with a further, preferably inhomogeneous, magnetic field G1, G2, G3 or by means of several further, preferably inhomogeneous, magnetic fields G1, G2, G3. Method (100) according to one of claims 7 to 10, characterized by obtaining (120) image data (70) from the starting material (14) and / or the partially generated 3D structure (12), and further manufacturing the 3D structure taking into account the image data (70).

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