Experimental digital fabrication workflows are increasingly common in human-computer interaction research, but are difficult to reproduce. We present Tandem, a software library that lets a fabricator implement an end-to-end fabrication workflow as a computational notebook program that others can run to physically reproduce the workflow. Tandem notebook programs read and write to CAD and CAM software, project augmented reality interfaces onto machines for manual interventions, and directly control fabrication machines. Fabricators can also denote potential mismatches between the physical and the digital as explicit assertions in code. Using two-sided CNC milling as an example, we demonstrate how to implement a complex workflow as a single program that can be re-run by others while supporting quality control and improving reproducibility.
doi.org/10.1145/3613904.3642751
The development of low-cost and non-invasive biosensors for monitoring electrochemical biomarkers in sweat holds great promise for personalized healthcare and early disease detection. In this work, we present ecSkin, a novel fabrication approach for realizing epidermal electrochemical sensors that can detect two vital biomarkers in sweat: glucose and cortisol. We contribute the synthesis of functional reusable inks, that can be formulated using simple household materials. Electrical characterization of inks indicates that they outperform commercially available carbon inks. Cyclic voltammetry experiments show that our inks are electrochemically active and detect glucose and cortisol at activation voltages of -0.36 V and -0.22 V, respectively. Chronoamperometry experiments show that the sensors can detect the full range of glucose and cortisol levels typically found in sweat. Results from a user evaluation show that ecSkin sensors successfully function on the skin. Finally, we demonstrate three applications to illustrate how ecSkin devices can be deployed for various interactive applications.
doi.org/10.1145/3613904.3642232
Woven beads, a structured fabric category, comprises interconnected rows of beads joined by fiber strands. While the stiffness of woven beads can be adjusted by relying on fiber tension during fabrication, the resulting shape and stiffness properties remain fixed. This study explores the potential of tunable shape and stiffness in woven beads, offering adaptability in comfort, functionality, and form factor. By leveraging Pneumatic Artificial Muscles (PAMs), we employ a state-of-the-art technique for dynamically modulating fabric stiffness through mechanical constraints in bead form. This approach enables a modular and scalable fabrication process, fostering programmability in mechanical properties. Our investigation encompasses diverse bead iterations and stitching patterns to broaden their applicability in fabric behavior including degree of freedom, stretchability, permeability, and textures. We evaluate the mechanical properties to differentiate design capabilities, and present techniques for locally adjusting stiffness. We showcase the versatility through applications, including variable stiffness wearables and shape-changing everyday objects.
doi.org/10.1145/3613904.3642401
Over recent years, there has been significant research within HCI towards free-form physical interactive devices. However, such devices are not straightforward to design, produce and deploy on demand. Traditional development revolves around iterative prototyping through component-based assembly, limiting device structure and implementation. Material-centric personal display fabrication (DisplayFab) opens the possibility of decentralised, configurable production by low-skill makers. Currently, DisplayFab is severely limited by its embryonic stage of development, the complexity of involved processes and materials, and the challenges around designing interactive structures. We present a development framework to provide a path for future research. DisplayFab has been developed by identifying 4 key breakpoints in the existing “Personal Fabrication” framework: Material and Deposition, Conception and Software, Feedback and Interactivity and Responsible Innovation. We use these breakpoints to form a targeted literature review of relevant work. Doing this we identify 30 challenges that act as roadmap for future research in DisplayFab.
doi.org/10.1145/3613904.3642708
Extended Reality (XR) allows in-situ previewing of designs to be manufactured through Personal Fabrication (PF). These in-situ interactions exhibit advantages for PF, like incorporating the environment into the design process. However, design-for-fabrication in XR often happens through either highly complex 3D-modeling or is reduced to rudimentary adaptations of crowd-sourced models. We present pARam, a tool combining parametric designs (PDs) and XR, enabling in-situ configuration of artifacts for PF. In contrast to modeling- or search-focused approaches, pARam supports customization through embodied and practical inputs (e.g., gestures, recommendations) and evaluation (e.g., lighting estimation) without demanding complex 3D-modeling skills. We implemented pARam for HoloLens 2 and evaluated it (n=20), comparing XR and desktop conditions. Users succeeded in choosing context-related parameters and took their environment into account for their configuration using pARam. We reflect on the prospects and challenges of PDs in XR to streamline complex design methods for PF while retaining suitable expressivity.
doi.org/10.1145/3613904.3642083