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ExoBreast

Moldable, Customizable, and Shape-Changing Prosthesis for Breast Cancer Survivors

By Rosalie Lin, Olaitan Adisa

Advisor: Lining Yao

This research proposes an innovative method of merging hand weaving and digital fabrication techniques to create moldable, conformable, and shape-reversible fabric. We will introduce two Polylactic Acid (PLA) manipulation methods to produce either yarn or scaffold with a desktop 3D printer. Also, we contribute an end-to-end pipeline to produce a customized prosthesis from the digital workflow (3D scanning, flattening algorithm) to physical fabrication (3D printing, weaving, hand-modeling). Our design allows the end-users to create breast prostheses with tailored fitting to their own bodies. Overall, ExoBreast presents a novel breast prosthesis as a one-piece garment that offers specific features such as lightweight, moldability, and affordability as opposed to traditional silicone prosthesis.

Reversible, Customizable Shaping of Prosthesis

Our main concept is to enable end-users to easily shape their Exo-Breast at its soft, tunable states by 1) heating it up to 60-70°C with easily accessible home appliances, and 2) remodeling it on their body silhouette or a printed customized mold. This shape-reversible materiality enables end-users to customize one-piece fabric upon their demands both aesthetically and functionally.

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Computational Pipeline

An overview of the pipeline is divided into the following stages: (a) body scanning to get the silhouette, (b) generating breast prosthesis on the scanned body, (c) 3D printing the breast area as the physical mold, (d-g) transforming 3D volume to the 2D pattern with flattening algorithm, (h-j) 3D printing the scaffold and weaving it with off-the-shelf yarns, (k-m) heating and molding the ExoBreast on the pre-printed breast mold or mannequin, and (n-o) attaching the ExoBreast to fit garment design. The overall pipeline proposes an end-to-end procedure for a rapid-customizable prototype

Body Scan & Flattening Algorithm

Body scanning is a process to capture the silhouette of the users. In a single mastectomy context, we can mirror the remaining

breast to generate an identical prosthesis for the asymmetrical silhouette. For double mastectomy survivors, we can customize

the breast size, curvature, and position to generate two brand-new prostheses. The flattening algorithm is applied from Geodesy (Gu et al) to transform from volumetric geometry to flat shape in one step. This method substitutes the traditional tailoring process and allows flat fabrication.

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Fabrication Methods & Material Properties

Build on top of the shape-memory property of thermoplastic, we have two fabrication approaches: For a method: We leverage the heat-drawing technique from a desktop 3d printer to deploy the PLA into thin, soft, and lightweight yarns. For b method: We print the PLA as a scaffold, in which it functions not only as material but as a loom, the weaving tool. By weaving off-the-shelf yarns with PLA yarn or scaffold, we are able to produce a piece of shape-reversible fabric without the exposure of thermoplastic.

 

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Woven Structure enables Multi-stretchability

Due to some deviation of transformation from 3D volume to 2D shape or vice versa, we look into stretchability as a parameter to adjust the fabric’s 3D geometry. We zoom into the weaving pattern to see how implementing different angles between the warp and weft axis can result in various levels of stretchability. Woven fabrics are anisotropic materials with different elastic constants based on the direction of applied tensile force when the direction of tensile force is 45 degrees to the direction of the weave, the Poisson's ratio, and the modulus of elasticity is the highest for fabric.

 

The same boundary area but different weaving patterns can result in different 3D geometry after being stretched and molded at the triggered soft state. End-users are thus able to hands-on optimize the prosthesis upon their aesthetic (size, curvature) or functional (stiff, soft) preferences.

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Multi-stiffness by embedding Different Density 

The shape-holding capability relates to the stiffness of the fabric. We then leverage different levels of yarn density to enable different levels of softness within one piece. The main idea is to fabricate a prosthesis in one run with both rigid support for the underwire region and softness to the rest of the area. 

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Interview with Breast Cancer Survivors

This is an iterative design process, in which we had in-depth interviews with three survivors at different phases of application development, as shown in figure 8. Each iteration consists of our prototype demo and survivor’s feedback, with one followed by the other sequentially. We started off by introducing our concept, better understanding their experience with the current prosthesis and their expectations, and asking them to conduct a survey. The interviews are conducted over Zoom, while the prototype is presented by video.

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