WO2023059334A1

WO2023059334A1 - Compound articles representing body portions

Info

Publication number: WO2023059334A1
Application number: PCT/US2021/054111
Authority: WO
Inventors: Clara REMACHA CORBALAN; Roger FADURDO ORELLANA; Virginia Palacios Camarero; Abdel Hakim MOUSTAFA
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2021-10-08
Filing date: 2021-10-08
Publication date: 2023-04-13

Abstract

In an example, a compound article comprises an internal support structure generated using additive manufacturing. In some examples the compound article further includes a flexible material enveloping and supported by a portion of the support structure. The flexible material may be representative of a characteristic of a portion of a human or animal body.

Description

COMPOUND ARTICLES REPRESENTING BODY PORTIONS

BACKGROUND

[0001] Additive manufacturing techniques may generate a three-dimensional object through the solidification of a build material, for example on a layer-by-layer basis. In examples of such techniques, build material may be supplied in a layer-wise manner and the solidification method may include heating the layers of build material to cause melting in selected regions. In other techniques, chemical solidification and/or binding methods may be used.

BRIEF DESCRIPTION OF DRAWINGS

[0002] Non-limiting examples will now be described with reference to the accompanying drawings, in which:

[0003] Figure 1 is an example of a compound article;

[0004] Figure 2 is an example of an internal support structure of a compound article and a mould;

[0005] Figure 3 is an example of a method for manufacturing a compound article;

[0006] Figure 4 is an example of a method for manufacturing a compound article; and

[0007] Figures 5 and 6 are examples of a machine-readable medium associated with a processor. DETAILED DESCRIPTION

[0008] Additive manufacturing techniques may generate a three-dimensional (3D) object through the solidification of a build material. In some examples, the build material is a powder-like granular material, which may for example be a plastic, ceramic or metal powder and the properties of generated objects may depend on the type of build material and the type of solidification mechanism used. Build material may be deposited, for example on a print bed and processed layer by layer, for example within a fabrication chamber. According to one example, a suitable build material may be Polyamide materials (e.g. PA12, PA11), Thermoplastic Polyurethane (TPU) materials, Thermoplastic Polyamide materials (TPA), Polypropylene (PP) and the like. In still other examples, build materials may comprise metals or curable liquids.

[0009] In some examples, selective solidification is achieved through directional application of energy, for example using a laser or electron beam. In other examples, at least one print agent may be selectively applied to the build material, and may be liquid when applied. For example, a fusing agent (also termed a ‘coalescence agent’ or ‘coalescing agent’) may be selectively distributed onto portions of a layer of build material in a pattern derived from data representing a slice of a 3D object to be generated. The data may be derived from a digital or data model of the object, e.g. object model data which provides a data, or virtual, model of an object to be generated. The fusing agent may have a composition which absorbs energy such that, when energy (for example, heat) is applied to the layer, the build material to which it has been applied heats up, coalesces and solidifies, upon cooling, to form a slice of the 3D object in accordance with the pattern. A suitable fusing agent may be an ink-type formulation comprising carbon black. Such a fusing agent may comprise any or any combination of an infra-red light absorber, a near infra-red light absorber, a visible light absorber and a UV light absorber. In other examples, for example fused deposit modelling techniques, molten materials may be deposited in intended locations to form a 3D object.

[0010] As noted above, additive manufacturing systems may generate objects based on structural design data. This may involve a designer determining a data model of an object to be generated, for example using a computer aided design (CAD) application. The model may define the solid portions of the object. To generate a 3D object from the model using an additive manufacturing system, the model data can be processed to define slices or parallel planes of the model. Each slice may define a portion of a respective layer of build material that is to be solidified or caused to coalesce by the additive manufacturing system. [0011] Medical students and professionals, such as doctors, surgeons or veterinary surgeons may use objects which represent a portion of an animal or a human body to practice or to learn a particular medical procedure, such as surgery. The object may be intended to mimic some property of the body it is intended to represent, for example any or any combination of the shape, texture, hardness, flexibility, appearance, or other physical property of the tissue of the body. Real animals or cadavers may be used for this purpose. However, they may be expensive and impractical and there can be various logistical and ethical issues associated with such practices. Furthermore, the properties of tissues of cadavers may be different to those of living patients, for example due to the use of preservative substances in the embalming process.

[0012] Mannequins or so-called ‘bench models’ may also be used. However, they tend to lack anatomical accuracy or realism. Furthermore, they may not represent specific pathologies.

[0013] Figure 1 shows a cross section of a compound article 100 comprising an internal support structure 102 and a flexible material 104. The flexible material 104 may be selected to have characteristics, or physical properties, similar to the material (e.g. tissue) it is intended to represent. In this example the compound article is intended to represent a human torso and the flexible material 104 is intended to mimic the skin and other soft tissue of the torso.

[0014] The characteristic which the flexible material 104 represents or includes may be a characteristic of a human or animal body, for example at least one of a shape, dimension, texture, hardness, flexibility, resistance to sewing or cutting, colour, ability to be cut or pierced, haptic feedback while touching, cutting or sewing or the like. More generally, the flexible material 104 may represent a characteristic of the article which the compound article 100 is intended to represent. In this example, the flexible material 104 may be formed to have an external surface in the same, or substantially similar, shape and size to the portion of the body which the compound article 100 is intended to represent. The material of the flexible material 104 may also be selected such that it has a similar texture, hardness, color and/or flexibility as the body portion which it is intended to represent.

[0015] As an example, the flexible material may comprise silicone. The flexible material 104 may be unable to support itself, or may be at least somewhat prone to damage or deformation during handling, and therefore an internal support structure 102 is provided within the flexible material to ensure the shape of the body portion which it is intended to represent is maintained.

[0016] The internal support structure 102 is generated using additive manufacturing. Additive manufacturing may provide an internal support structure 102 with any suitable shape to support the flexible material 104, and/or an internal support structure 102 which is to be enveloped by the flexible material during manufacture of the compound article 100. In some examples, the internal support structure 102 may comprise a 3D lattice structure, i.e. comprising linked struts with a relatively large amount of empty space therebetween, wherein at least some of the empty space may be filled by the flexible material 104 during manufacture of the compound article 100. Additive manufacturing allows construction of relatively complex shapes that would otherwise be challenging to manufacture. The flexible material 104 envelops at least a portion of the support structure 102 and is supported by a portion of the support structure 102. The internal support structure 102 may be substantially within and surrounded by the flexible material 104 so that the properties of the flexible material 104, such as texture, appearance or hardness are relatively unaffected while the flexible material 104 is sufficiently supported to maintain its intended shape, even in some examples with repeated handling.

[0017] The flexible material 102 is representative of a characteristic of a portion of a human or animal body. In this example the compound article represents a human torso, however in other examples the compound article may represent another body part such as limbs (e.g. legs, arms, feet, hands), joints (e.g. elbows, shoulder, ankles, knees), organs (e.g. hearts, livers, kidneys, lungs, brain), soft tissues, or any other body part of a human or animal. In some examples, the compound article may represent multiple body parts and may represent a subset of a body or a whole body. In some examples, multiple compound articles representing different body portions may be used together, for example compound articles representing organs (e.g. heart, lungs, liver, etc.) may fit within a compound article representing a torso.

[0018] The internal support structure 102 may have a higher stiffness than the flexible material 104. In some examples, the compound article may be intended to maintain some flexibility to better mimic the body portion it is intended to represent, for example, a compound article representing a heart may be designed to be sufficiently flexible that it can be manipulated and squeezed by a hand to allow it to be used for training for surgeries which involve squeezing the heart. Therefore, the internal support structure 102 may be designed to allow the flexible material to be manipulated, squeezed, bent or flexed. This may be achieved by generating the internal support structure 102 from a material which has a high flexibility, by designing an internal support structure 102 which comprises relatively thin struts having a composition and/or physical structure which allow them to bend or providing no internal support structure 104 at certain regions within the flexible material 102. Thus, the internal support structure 102 may also be somewhat flexible in some examples.

[0019] In some examples the compound article 100 comprises a single internal support structure 102, however in other examples the compound article 100 may comprise several internal support structures 102, for example two or more internal support structures 102. For example, a relatively small compound article 100 such as a compound article 100 which represents a heart may comprise a single internal support structure 102 whereas a relatively large compound article 100 such as a compound article 100 representing a torso, as depicted in Figure 1 , may comprise two internal support structures 102.

[0020] In some examples the support structure 102 extends substantially throughout the flexible material 104, for example being defined to extend to within a predetermined distance of the surface of the compound article 102. However, in some examples the support structure 102 may extend throughout a portion of the flexible material 104, with the remaining flexible material 104 being unsupported by the support structure 102. For example the compound article may be intended to represent a portion of a body which comprises a relatively flexible region and a relatively less flexible region. In such an example the relatively less flexible region may comprise a portion of the support structure 102 whereas the relatively flexible region does not comprise the support structure 102.

[0021] In some examples the compound article 100 is a surgical training apparatus. A surgical training apparatus may be used by medical students, doctors, surgeons or veterinary surgeons to practice or learn new techniques. Surgical training apparatus may also be used to develop and evaluate new equipment, such as devices used during surgery. For example, the surgical training apparatus may be used to develop and evaluate robots for use in robotics-assisted surgery before using them with real patients. In other examples, the surgical training apparatus may be used to develop and learn minimally invasive surgical techniques, such as laparoscopic surgery.

[0022] In some examples the compound article 100 may represent a specific pathology. For example, the compound article 100 may comprise a feature which represents the pathology, such as a tumour, a wound, a congenital heart disease, any cardiopathy (e.g. in the mitral valve), an orthopaedic injury, a spine deformation, a broken ligature or muscle, broken meniscus or cartilages, arteria and vein prosthesis, broken or deformed (outgrown) bone or organs, thrombosis or arteria calcification or any other organ pathology. The compound article may be used to practice stitching broken skin, ligature or muscle, removal, polishing or replacement of broken meniscus or cartilages, cannula insertion or simulation of heart valves. By providing a compound article which is constructed using parts generated in additive manufacturing, it enables the generation of different compound articles representing a range of different pathologies, different types of patients, for example children and adults, male and female patients, and patients of different body weights.

[0023] The flexible material 104 may be formed using a process other than additive manufacturing. For example the flexible material 104 may be formed by locating the internal support structure 102 at least partially within a mould and adding a flowable material to the mould so that the flowable material surrounds the internal support structure 102. The flowable material may then solidify or be cured (e.g. by natural curing, thermal curing or UV curing) to provide a solid flexible material 104 which envelops or surrounds at least a portion of the internal support structure 104. The mould may be designed so that the interior surface of the mould represents the shape of the external surface of the body portion which is intended to be represented by the compound article 100 and/or the internal support structure 102 may be designed so as not to impede the flow of the flowable material, for example having voids (e.g. holes, perforations or apertures) which are sufficiently large and/or a lattice which is sufficiently open to inhibit the formation of bubbles or air pockets in the flowable material, and hence the flexible material 104. The support structure 102 may also be shaped to avoid locations where air may accumulate and become trapped, such as convex shapes. Furthermore, struts of the lattice may be relatively thin and comprise rounded surfaces to allow the flowable material to flow without forming bubbles. In some examples the strut thickness may be 1 mm to 5mm, or 1 mm to 10mm, or some other thickness.

[0024] Figure 2 is an example of an internal support structure 202 for use in a compound article, such as the compound article 100 shown in Figure 1. Figure 2 also shows an example of a mould 204a, 204b which may be used to form the flexible material 104 around the internal support structure 202. In this example the mould 204a, 204b comprises two parts, however in other examples the mould 204a, 204b may be formed from a single part, or it may comprise more than two parts. [0025] In this example, a portion of the internal support structure 202 of the compound article comprises a lattice structure 206. The lattice structure 206 allows the flowable material to flow between struts forming the lattice and fill the space within the mould 204a, 204b. The lattice structure 206 may also provide a relatively lightweight internal support structure 202 while also being relatively strong.

[0026] In this example, a portion of the lattice structure 206 of the support structure comprises a Voronoi lattice. A Voronoi lattice may be formed from a plurality of Voronoi cells, wherein the lattice is formed from struts along each edge of each Voronoi cell. The Voronoi cells may be defined by a random or pseudo-random arrangement of seed points and each Voronoi cell comprises all points which are closer to the seed point of that cell than a seed point of a different cell. Defining the Voronoi lattice may comprise defining a strut thickness and/or a cell size and determining the Voronoi lattice based on these dimensions. A Voronoi lattice may provide a strong internal support structure 202 while allowing the flowable material to readily fill the spaces in the lattice 206.

[0027] The mould 204a, 204b may be generated using additive manufacturing. The mould 204a, 204b may be formed from the same or different material as the internal support structure 202. In some examples the mould 204a, 204b is generated in the same additive manufacturing operation as the internal support structure 202. In such examples the mould 204a, 204b may be physically connected to the internal support structure 202 by a connection also formed using additive manufacturing. When the flexible material has been formed within the mould, the mould may be removed and the connection between the mould 204a, 204b and the internal support structure 202 broken or separated.

[0028] In other examples the mould 204a, 204b is generated in a separate additive manufacturing operation to the internal support structure 202. The mould 204a, 204b may be reused to form multiple compound articles.

[0029] In some examples a portion of the internal support structure 202 extends outside of the flexible material to provide a connecting element 212. In some examples the internal support structure 202 may comprise one connecting element 212, whereas in other examples the internal support structure 202 may comprise two or more connecting elements 206. In the example shown in Figure 2 the internal support structure 202 comprises connecting elements 212 which correspond to connecting elements 208a, 208b of the mould 204a, 204b. The connecting elements 212, 208a, 208b allow the first part of the mould 204a to be connected to the internal support structure 202 and to the second part of the mould 204b. In this example the connecting elements 212, 208a, 208b comprise holes which align when the parts are assembled. A bolt or rod may be inserted through the aligned holes to allow the parts to be securely connected together. In other examples a different type of fastener may be used, such as screws. In some examples the connecting elements 212, 208a, 208b may comprise another means of connecting the different parts, for example they may comprise corresponding holes, slots and protruding features, or snap fit features which allow connection of the different parts. When a mould 204a, 20b comprises multiple parts a seal may be provided along an edge (or edges) where the parts of the mould 204a, 204b meet to prevent the flowable material from leaking from the mould 204a, 204b.

[0030] In this example the flexible material is formed around the lattice 206 of the internal support structure 202 but not around the connecting element 212, or at least a portion of the connecting element remains uncovered. Therefore, the connecting elements 212 protrude out of the flexible material of the compound article. In this example the connecting element 212 does not comprise a lattice structure, however in other examples the connecting element 212 may comprise a lattice structure, for example similar to the lattice structure 206.

[0031] In some examples the connecting element 212 may be used to connect the compound article, once manufactured, to another object. For example the connecting element 212 may be used to securely mount or fasten the compound article to allow interaction with the compound article without moving the compound article. In some examples multiple compound articles may comprise corresponding connecting elements so that the compound articles can be connected together to form a larger object. For example, a compound article representing a torso may be connectable to compound articles representing organs which may in some examples be connectable within an open space in the interior of the compound article representing the torso. In some examples a compound article representing a torso may be externally connectable to other compound articles, for example representing limbs.

[0032] In some examples the connecting elements 212 are used for either connecting the internal support structure 202 to the mould 208a, 208b during manufacture or in some examples the connecting elements 212 are used for mounting the internal support structure 202/compound article, or connecting the article to other parts, during use of the compound article, once manufactured. In some examples the connecting elements 212 are used both during manufacture and use of the compound article. [0033] In some examples a frame may be used to connect to a connecting element 212 of a compound article or compound articles. The frame may be created using additive manufacturing. The frame may represent a portion of the body. For example the frame may represent a rigid body part, such as bone, teeth or skull. Therefore, the frame may act to support a compound article(s), to connect multiple compound articles and/or to represent a portion of the body.

[0034] In some examples the lattice support structure 202 comprises struts and the strut thickness is variable throughout the structure based on properties of the flexible material surrounding the strut. For example, if the stut is surrounded by a relatively large amount of flexible material it may be supporting a relatively large mass and therefore should be thicker. Conversely if a strut is surrounded by a relatively thin portion of flexible material, it may support a smaller mass and therefore can be thinner. In some examples the strut thickness may be selected based on the intended properties of the lattice. For example if the lattice 206 of the internal support structure 202 is intended to be relatively flexible the strut thickness may be relatively thin and if it is intended to be relatively rigid the strut thickness may be thicker. In some examples the strut thickness may vary throughout the lattice 206, which may provide a lattice 206 which is relatively more flexible in some regions and relatively rigid in other regions. This may be used to simulate a portion of the body which has a different flexibility in different locations. Similarly the cell size of the lattice may vary throughout the support structure based on properties of the material surrounding the support structure and/or intended properties of the support structure and/or compound article. In some examples the cell size in the Voronoi lattice is in the range 0.5cm to 2.5cm. In some examples, it may be intended to minimise, or substantially minimise, the support structure while providing the intended amount of support, as this may allow the properties of the flexible material to dominate as the properties of the compound article.

[0035] In the example internal support structure 202 and mould 204a, 204b shown in Figure 2, the lattice 206 of the internal support structure 202 comprises an access hole 210. The access hole 210 may allow access to the interior of the compound article, for example to manipulate the interior of, or objects in the interior of the compound article. The flexible material may comprise a corresponding access hole in the same location as the access hole 210 of internal support structure to allow hands, cameras or surgical implements to be inserted.

[0036] In some examples the flexible material comprises a silicone. In some examples the silicone is a platinum-cured silicone. Platinum-cured silicone may be formed from two components (components A and B, which in some examples may be mixed in a one-to- one ratio to a three-to-one ratio). In some examples further components are added to form the silicone. The mixture may readily flow through the mould and cure at room temperature with no exothermic reaction to form the solid silicone flexible material. In other examples, a silicone may be cured with natural cooling, UV curing or thermal curing.

[0037] Silicone provides a flexible material which is suitable for simulating soft body tissues because of its flexibility, texture and hardness (i.e. low shore A). However, silicone alone may not keep its intended shape over time and use without the additional support provided by the internal support structure. An internal support structure also makes the compound article 100 more durable.

[0038] In some examples the flexible material may be a material which does not comprise silicone, for example it may comprise a hydrogel, depolymerized rubber (DPR), polyurethane casting rubber or c-silicone.

[0039] Although flexible materials, such as silicone, are suitable for simulating soft body tissue, it may not be practical to generate such materials using additive manufacturing in all examples. However, the mould used for forming the flexible material may be created using additive manufacturing.

[0040] In some examples the mould 204a, 204b may comprise further features. For example the mould 204a, 204b may comprise features to assist in unmoulding (i.e. separating the mould and the flexible material). For example unmoulding screws, bolts or protrusions may be provided to help a user remove the mould or parts of the mould 204a, 204b when the flowable material has solidified. In some examples a sealing ring or gasket may be provided along an edge or along multiple edges (in particular edges where multiple parts of the mould 204a, 204b meet) to reduce leakage of the flowable material. In some examples vents may be provided in the mould 204a, 204b to allow gasses to escape to reduce formation of bubbles in the flowable material and therefore the flexible material. In some examples the mould 204a, 204b comprises infill holes, which may be holes located to allow injection of the flowable material into corners, edges or other locations where the flowable material may not readily flow. In some examples the mould 204a, 204b may comprise mould insert locations which allow insertion of mould inserts, wherein the mould inserts comprise a serial number or other identification such as production batch or date. The identification on the mould insert may be embossed such that the identification information is imprinted on the flexible material, or the mould insert may become embedded in the flexible material permanently.

[0041] Figure 3 is an example of a method, which may comprise a method of manufacturing a compound article. The compound article may be the compound article described in relation to Figure 1. In this example the method is carried out in part by processing circuitry, which may comprise at least one processor.

[0042] The method comprises, in block 302, obtaining a three-dimensional data model representing a support structure. As used herein, the data model may be a model which defines the size and shape of the object to be generated. The data model may for example comprise a Computer Aided Design (CAD) model, and/or may for example be a STereoLithographic (STL) data file or a 3D Manufacturing Format (3MF) data file. The data model may comprise a representation of the object, for example as a plurality of voxels or a mesh model. In some examples, the model may be retrieved from a memory or over a network or the like. In other examples, the data model may be derived.

[0043] For example, a space having the intended outer dimensions of the support structure may be defined, and a lattice may be derived to fill the space. In other examples, a lattice may be designed so as to lie at a predetermined distance below the surface of a space, for example to allow a depth of flexible material to be formed thereover when the compound article is generated, for example to mimic human skin and/or fat deposits or other soft tissue. Therefore, there may be an intended offset, or inset, from the exterior surface of the portion of the compound article or the inside surface of the mould.

[0044] For example the lattice may be a Voronoi lattice which is defined to fill the space. For example the seed points of the Voronoi lattice may be randomly, pseudo- randomly or deterministically distributed throughout the space and Voronoi cells determined such that the Voronoi lattice fills the space. In other examples other space filling lattices, such as cuboids, triangular, hexagonal or a combination thereof may be generated. For example, this may comprise scaling and/or replicating a base unit defined for a cell or cells to fill the void. As noted above, in some examples, the strut thickness may vary based on an intended flexibility of a portion of the structure. Moreover, other attributes of the lattice such as cell size (or average cell size for a Voronoi lattice) may vary over the model so as to provide intended attributes for the support structure.

[0045] In some examples the data model may be derived from a digital or a data model representing the object to be generated, for example from a virtual model of the object. Such a model may be from a CAD model designed to represent the object or obtained from another physical object. The model may be generated so as to provide, for example, intended flexibility and/or strength characteristics in the generated object.

[0046] The method comprises, in block 304, generating the support structure using additive manufacturing based on the received data model. In order to generate an object, print agent may be selectively deposited onto portions of build material. For example, a fusing agent may be deposited in areas which are intended to be solidified to generate the object.

[0047] Generating the object using additive manufacturing may comprise obtaining a data model describing which portions of build material print agent is to be deposited upon, based on the data representing the object to be generated. Print agent coverage amounts may for example be defined as an area coverage, that is the volume of printing agent to be deposited per unit area, or as a percentage coverage, that is, the percentage of an area which is intended to be covered with the print agent. In some examples, it may be defined as a contone level. The locations to which print agent drops are applied and/or the amount and/or size of such drops may be determined according to an intended coverage, for example using halftoning techniques and the like.

[0048] In other examples, other additive manufacturing techniques may be used to generate the object. For example, directional energy and/or a material deposit apparatus may be controlled so as to produce the support structure specified in the data model.

[0049] The method comprises, in block 306, depositing a flowable material in a mould surrounding the support structure. The flowable material may be a liquid, a slurry, granules or a powder. For example, the flowable material may be a material which cures to form a silicone material, for example a platinum-cured silicone. The flowable material is to solidify to form a flexible material representative of a characteristic of a portion of a human or animal body around a portion of the support structure. For example the shape, dimension, texture, hardness or flexibility of the flexible material may be similar to that of the portion of the body the compound article is intended to represent. The characteristic may, in some examples, be at least partially provided by the thickness of a layer of the flexible material which is provided outside the support structure.

[0050] Figure 4 provides an example of the method of Figure 3. As discussed in greater detail below, blocks 402, 406 and 410 may provide an example of the method of blocks 302, 304 and 306 described in relation to Figure 3. [0051] Block 402 comprises obtaining a three-dimensional data model representing a support structure, and may correspond to block 302 of Figure 3.

[0052] Block 404 comprises obtaining a three-dimensional model representing the mould. The model representing the mould may be obtained in a similar manner to obtaining the model representing the support structure.

[0053] In some examples obtaining the model representing the support structure and/or obtaining the model representing the mould comprises obtaining a three-dimensional model, such as a Computer Aided Design (CAD) model, STereoLithographic (STL) data file or a 3D Manufacturing Format (3MF) data file, representing the portion of the body which the compound article is to represent. Such a model may be obtained by imaging a real body, for example using medical imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI). The model representing the internal support structure and/or the model representing the mould may be derived from the model representing the portion of the body. For example the interior surface of the mould may correspond to the exterior surface of the portion of the body.

[0054] In some examples obtaining the model representing the mould comprises creating a portion of the model which represents a connecting element, such as the connecting element 212 described in relation to Figure 2. In some examples obtaining the model representing the mould comprises creating an opening, a hole or corresponding connecting element in the model representing the mould. For example, an opening or hole in the model representing the mould may be formed to allow the connecting element of the support structure to extend outside of the mould such that when the compound article is formed, the connecting element of the support structure extends outside of the flexible material. In some examples the hole or corresponding connecting element in the mould allows the support structure to be connected to the mould, so that the support structure may be accurately positioned within the mould.

[0055] In some examples the instructions to create the model representing the support structure comprise instructions to identify a region of the portion of the article in which to provide the support structure. For example, the locations which are more than a threshold distance from an exterior surface of the portion of the body may be identified as locations where the support structure should be provided. In other words, the support structure may be provided in a region offset, or inset, from the exterior surface of the portion of the body or the inside surface of the mould. In some examples the offset is 1 cm or greater than 1 cm. In some examples the offset is in the range 0.5cm to 3cm. The offset or inset may for example be selected to provide a depth of flexible material to mimic human skin and/or fat deposits or other soft tissue.

[0056] Block 406 comprises generating the support structure using additive manufacturing based on the data model representing the support structure and block 408 comprises generating the mould using additive manufacturing based on the model representing the mould. The support structure and the mould may be generated using additive manufacturing as described in block 304 of Figure 3. In some examples a mould may be used to manufacture a single compound article. For example the compound article may represent a specific pathology, for example it may comprise a feature representing a tumour or a broken bone. In some examples the pathology represented may be specific to a particular patient, for example a patient may be imaged using medical imaging, such as MRI or CT, and their specific pathology recreated in the compound article. In examples where the mould is used to manufacture a single compound article, the mould and the support structure may be generated in a single additive manufacturing operation.

[0057] Block 410 comprises generating a connection between the support structure and the mould using additive manufacturing. The connection may be generated during an additive manufacturing operation in which both the support structure and the mould are being generated. Therefore, the mould and the support structure may form a single continuous object. A connection between the mould and support structure causes the support structure to be accurately aligned within the mould.

[0058] Block 412 comprises depositing a flowable material in a mould surrounding the support structure and may correspond to block 306 of Figure 3.

[0059] Block 414 comprises separating the mould and the support structure at the connection. When there is a connection between the mould and support structure, separating the mould and the support structure may comprise breaking the connection. In some examples the connection is a frangible connection. In other examples the connection may comprise interlocking or snap-fit components which can be separated. In other examples the connection may be formed with a connecting member, such as a bolt, rod or other fastener, and separating the mould and support structure may comprise removing the connecting member.

[0060] In this example the mould and the support structure are described as being connected by the connection. However, in other examples the mould and the support structure are generated as physically disconnected objects. The support structure and mould may not have a dedicated connection, but may be relatively aligned by corresponding datum points in the mould and support structure when the support structure is located within the mould.

[0061] When the mould and the support structure are generated separately in the same or in different additive manufacturing operations, the mould may be reused to manufacture multiple compound articles, whereas a new support structure is used for each compound article produced. Therefore, when the mould and support structure are generated in a single additive manufacturing operation one moulds and multiple support structures may be generated. When the mould and support structure may be generated in different additive manufacturing operations the mould and the support structure may be generated using different materials.

[0062] Figure 5 shows an example of a tangible machine readable medium 502 in association with a processor 504. The machine readable medium 502 stores instructions 506 which, when executed by the processor 504 cause the processor to carry out actions.

[0063] In this example, the instructions 506 comprise instructions 508 to cause the processor 504 to receive data representing a geometry of a portion of a human or animal body. The data may for example comprise a Computer Aided Design (CAD) model, and/or may for example be a STereoLithographic (STL) data file or a 3D Manufacturing Format (3MF) data file. The model may comprise a representation of the portion of the body, for example as a plurality of voxels or a mesh model. The model may be a generic model or in some examples it may represent a specific patient, type of patient or a specific pathology.

[0064] In this example, the instructions 506 comprise instructions 510 to cause the processor 504 to create a three-dimensional model (i.e. a data model, or virtual object) representing a mould to support a flowable material based on the received data. The interior surface of the mould as represented by the model may correspond to the exterior surface of the portion of the body represented by the data. The model representing the mould may comprise additional features, for example it may comprise connecting elements which may be used to connect the mould to the support structure or to secure the mould during manufacture of the compound article. In some examples the mould defined by the model may comprise multiple parts, for example as shown in Figure 2. In examples where the mould comprises multiple parts the connecting elements may be used to connect the parts together for receiving a flowable material. The flowable material may be a liquid, a slurry, granules or a powder, and may be cured or otherwise solidified or coalesced to form a flexible material, such as silicone.

[0065] In this example, the instructions 506 comprise instructions 512 to cause the processor 504 to create a three-dimensional model (i.e. a data model, or virtual object) representing a support structure to fit at least partially within the mould and to be at least partially surrounded by the flowable material based on the received data. The model representing the support structure may comprise a portion intended to be surrounded or enveloped by the flowable material. This portion may comprise a lattice structure. For example, the lattice structure may comprise a plurality of interconnected struts with open spaces therebetween. The lattice structure may be a regular lattice, for example with struts spaced at regular intervals. In some examples, the lattice may be a Voronoi lattice. In some examples, the outer dimensions for the support structure may be specified and a lattice may be created so as to provide the dimensions.

[0066] Regions may be identified in which the support structure is to be located. Such regions may be identified using an offset function relative to the surface on the inside of the mould or using an offset function relative to the exterior surface of the model representing the portion of the body. When the support structure comprises a lattice, the lattice may extend throughout this identified region.

[0067] In this example, the instructions 506 comprise instructions 514 to cause the processor 504 to generate instructions, executable by an additive manufacturing apparatus, which instruct the additive manufacturing apparatus to generate the support structure and the mould. The generated instructions may comprise instructions for an additive manufacturing apparatus to generate the support structure and to generate the mould in a single additive manufacturing operation or to generate them in separate additive manufacturing operations. The instructions may provide the three-dimensional models representing the mould and the support structure to an additive manufacturing apparatus and may instruct the additive manufacturing apparatus to generate the objects based on the received models.

[0068] Figure 6 shows a machine-readable medium 602 associated with a processor 604. The machine-readable medium 602 comprises instructions which, when executed by the processor 604, cause the processor 604 to carry out tasks.

[0069] In this example, the instructions 606 comprise instructions 508 to cause the processor 604 to receive data representing a geometry of a portion of a human or animal body, as described in relation to Figure 5. [0070] In this example, the instructions 606 comprise instructions 608 to cause the processor 604 to receive data describing the type of material to be supported by the support structure. The data describing the type of material may comprise a description of the material which will be used in the mould to surround the support structure. The description may describe the properties of the material, for example any or any combination of its density, flexibility, hardness, or any other relevant property. In some examples the description may list a compound or compounds present in the material.

[0071] In this example, the instructions 606 comprise instructions 510 to cause the processor 604 to create a three-dimensional model representing a mould to support a flowable material based on the received data, as described in relation to Figure 5.

[0072] In this example, the instructions 606 comprise instructions 610 to cause the processor 604 to create a three-dimensional model representing a support structure to fit at least partially within the mould and to be at least partially surrounded by the flowable material based on the received data. In this example creating the model representing the support structure is based on the type of material in the data received in instructions 608. For example, if the type of material is a relatively flexible material, a material with a low shore hardness or a relatively dense or thick material the support structure may be defined to be more rigid, for example by having thicker struts or a higher density of struts. Conversely if the flexible material is relatively rigid, has a high shore hardness or low density then a less rigid support structure may be defined. The cell size of the lattice forming the support structure may also vary based on the type of material. For example a smaller cell size, and therefore denser lattice structure may be used in regions which are intended to be stronger, for example to provide increased rigidity or which are intended to support a greater weight.

[0073] In some examples an opening in the support structure may be defined, for example to allow access to the interior of the compound article, for example to allow a user to insert their hands, a camera or surgical equipment. The compound article also comprises an opening in the flexible material in the same location. The opening may be provided by a large cell in that location. In some examples the support structure around the opening may be stronger around the opening to provide additional support, for example by having thicker struts or a smaller cell size.

[0074] In this example, the instructions 610 further comprise instructions 612 to create the model representing the support structure by defining a plurality of struts forming a lattice structure. In some examples the lattice structure is a Voronoi lattice. A Voronoi lattice may be defined as described in relation to Figure 2.

[0075] In some examples creating the model representing the support structure comprises creating a connecting element portion extending outside of the mould. The connecting element portion may be a connecting element 212 as described in relation to Figure 2.

[0076] In this example, the instructions 606 comprise instructions 514 to cause the processor 604 to generate instructions, executable by an additive manufacturing apparatus, which instruct the additive manufacturing apparatus to generate the support structure and the mould, as described in relation to Figure 5.

[0077] In some examples, the instructions 606 may comprise instructions to cause the processor 606 to carry out any or any combination of blocks 302, 304, 402 and 404.

[0078] Examples in the present disclosure can be provided as methods, systems or machine-readable instructions, such as any combination of software, hardware, firmware or the like. Such machine-readable instructions may be included on a computer readable storage medium (including but not limited to disc storage, CD-ROM, optical storage, etc.) having computer readable program codes therein or thereon.

[0079] The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure. Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart. It shall be understood that each block in the flow charts and/or block diagrams, as well as combinations of the blocks in the flow charts and/or block diagrams can be realized by machine readable instructions.

[0080] The machine-readable instructions may, for example, be executed by a general purpose computer, a special purpose computer, an embedded processor or processors of other programmable data processing devices to realize the functions described in the description and diagrams. In particular, a processor or processing apparatus may execute the machine-readable instructions. Thus, functional modules of the apparatus and devices may be implemented by a processor executing machine readable instructions stored in a memory, or a processor operating in accordance with instructions embedded in logic circuitry. The term ‘processor’ is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate array etc. The methods and functional modules may all be performed by a single processor or divided amongst several processors.

[0081] Such machine-readable instructions may also be stored in a computer readable storage that can guide the computer or other programmable data processing devices to operate in a specific mode.

[0082] Such machine-readable instructions may also be loaded onto a computer or other programmable data processing devices, so that the computer or other programmable data processing devices perform a series of operations to produce computer-implemented processing, thus the instructions executed on the computer or other programmable devices realize functions specified by block(s) in the flow charts and/or block diagrams.

[0083] Further, the teachings herein may be implemented in the form of a computer software product, the computer software product being stored in a storage medium and comprising a plurality of instructions for making a computer device implement the methods recited in the examples of the present disclosure.

[0084] While the method, apparatus and related aspects have been described with reference to certain examples, various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the present disclosure. It is intended, therefore, that the method, apparatus and related aspects be limited only by the scope of the following claims and their equivalents. It should be noted that the above- mentioned examples illustrate rather than limit what is described herein, and that those skilled in the art will be able to design many alternative implementations without departing from the scope of the appended claims.

[0085] The word “comprising” does not exclude the presence of elements other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims.

[0086] The features of any dependent claim may be combined with the features of any of the independent claims or other dependent claims.

Claims

1 . A compound article comprising: an internal support structure generated using additive manufacturing; and a flexible material enveloping and supported by a portion of the support structure, wherein the flexible material is representative of a characteristic of a portion of a human or animal body.

2. A compound article as claimed in claim 1 wherein the compound article is a surgical training apparatus.

3. A compound article as claimed in claim 1 wherein a portion of the internal support structure comprises a lattice structure.

4. A compound article as claimed in claim 3 wherein the lattice structure comprises struts and the strut thickness is variable throughout the structure based on properties of the flexible material surrounding the strut.

5. A compound article as claimed in claim 3 wherein a portion of the lattice of the support structure comprises a Voronoi lattice.

6. A compound article as claimed in claim 1 wherein the characteristic is at least one of a shape, dimension, texture, hardness or flexibility.

7. A compound article as claimed in claim 1 wherein the flexible material comprises a silicone.

8. A compound article as claimed in claim 1 wherein a portion of the internal support structure extends outside of the flexible material to provide a connecting element.

9. A method comprising; obtaining a three-dimensional data model representing a support structure; generating the support structure using additive manufacturing based on the received data model; depositing a flowable material in a mould surrounding the support structure; wherein the flowable material is to solidify to form a flexible material representative of a characteristic of a portion of a human or animal body around a portion of the support structure.

10. A method as claimed in claim 9, further comprising: obtaining a three-dimensional model representing the mould; and generating the mould using additive manufacturing based on the model representing the mould.

11. A method as claimed in claim 10 wherein the mould and the support structure are generated as physically disconnected objects.

12. A method as claimed in claim 10 wherein the method further comprises: generating a connection between the support structure and the mould using additive manufacturing; and separating the mould and the support structure at the connection.

13. A machine-readable medium comprising machine-readable instructions which, when executed by a processor, cause the processor to: receive data representing a geometry of a portion of a human or animal body; create a three-dimensional model representing a mould to support a flowable material based on the received data; create a three-dimensional model representing a support structure to fit at least partially within the mould and to be at least partially surrounded by the flowable material based on the received data; and generate instructions, executable by an additive manufacturing apparatus, which instruct the additive manufacturing apparatus to generate the support structure and the mould.

14. A machine-readable medium as claimed in claim 13 wherein creating the model representing the support structure comprises instructions to define a plurality of struts forming a lattice structure.

15. A machine-readable medium as claimed in claim 13 further comprising instructions to: receive data describing the type of material to be supported by the support structure, and wherein creating the model representing the support structure is based on the type of material.