Xpandables: Single-filament Multi-property 3D Printing by Programmable Foaming

We propose a new approach to obtain local property variations in 3D-printed objects using a single-nozzle 3D printer and one filament. We use foaming filaments which expand at different rates due to different temperatures. We present an approach to harness this varying expansion by including parameters of the 3D printing process in the design space. This makes the foaming programmable and allows for achieving a wide variety of properties from a single material. We show how objects with locally varying shade, translucency, gloss, and texture can be fabricated. Our approach turns single-nozzle 3D printers into more versatile systems while eliminating the challenges of multi-material 3D printing. This is in contrast to the drive towards an increasing number of printable materials and more complex 3D printers. We demonstrate the capability of our approach by 3D printing objects with embedded barcodes, QR codes, and varying tactile properties.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Mechatronic Desig

Development of a 3D printed structural electronics force sensor

Structural electronics has garnered significant attention in the past decade. However, there remains a lack of a systematic approach in designing and manufacturing sensors that leverage both mechanical and electronic properties of materials for different applications. In this paper, we introduce a method for designing piezoresistive force sensors utilizing structural electronics and 3D printing techniques. Based on the principles of piezoresistive force sensing, we defined the geometric profile of the sensor by simultaneously maximizing strain and ensuring as uniform as possible stress distribution across the geometry. CAD models of the sensors were then formulated based on the optimized profile and fabricated using conductive filaments and the material extrusion 3D printing technique. Subsequently, we evaluated the accuracy, the sensitivity, and part-to-part variations of the sensors during loading and unloading. The influence of environmental temperature and humidity on the sensor's response were also investigated and compensated. Experiment results demonstrated the feasibility of the proposed method and revealed potential application domains, as well as limitations of the sensors.Emerging MaterialsMechatronic Desig