Mechanical behavior in interactive systems is typically fixed at fabrication through geometry and material selection. This paper introduces GrowMechanics, a Research-through-Design fabrication approach that explores mechanical design through biological growth rather than predefined specification. Positioning growth as a temporal design parameter and a form of material computation, we investigate how mechanical behavior can evolve over time through living processes. Our exploration centers on a living biohybrid joint fabricated by growing bacterial cellulose between porous scaffolds. The joint serves as a research probe to examine how sequential fabrication, through staged growth and intervention, shapes mechanical behavior. We identify consistent tendencies in growth-driven stiffness variation and flexible geometry matching, alongside structured, geometry-dependent responses that arise from the material’s hydrated and compliant nature. Thus, this work highlights a space of constrained predictability in growth-based mechanics, identifying factors that condition mechanical response and contributing design knowledge for HCI on how such behavior can be shaped through living fabrication.

Bio-based and bio-degradable materials have shown promising results for sustainable Human-Computer Interaction (HCI) applications, including shape-changing interfaces. However, the diversity of shape-changing behaviors achievable with these materials remains unclear as the fabrication knowledge is scattered across multiple research fields. This paper introduces SoftBioMorph, a fabrication framework that aims to integrate the fabrication know-how of sustainable soft shape-changing interfaces with biopolymers. Based on the example of Sodium Alginate, the framework contributes (1) a set of material synthesis processes that modify the biopolymer’s properties to fulfill different functions; (2) a set of DIY crafting-based assembling techniques that functionalize the material and assembling properties to achieve three primitive types of change in shape; and (3) a series of application cases that demonstrate the versatility of the framework. We further discuss limitations, research questions, and fabrication challenges, presenting a comprehensive approach to sustainable prototyping in HCI.

Living bio-materials are increasingly used in HCI for fabricating objects by growing. However, how to integrate electronics to make these objects interactive still needs to be clarified. This paper presents an exploration of the fabrication design space of Biohybrid Interactive Devices, a class of interactive devices fabricated by merging electronic components and living organisms. From the exploration of this space using bacterial cellulose, we outline a fabrication framework centered on the biomaterials‘ life cycle phases. We introduce a set of novel fabrication techniques for embedding conductive elements, sensors, and output components through biological (e.g. bio-fabrication and bio-assembling) and digital processes. We demonstrate the combinatory aspect of the framework by realizing three tangible, wearable, and shape-changing interfaces. Finally, we discuss the sustainability of our approach, its limitations, and the implications for bio-hybrid systems in HCI.

Designers and makers are increasingly interested in leveraging bio-based and bio-degradable ‘do-it-yourself’ (DIY) materials for sustainable prototyping. Their self-produced bioplastics possess compelling properties such as self-adhesion but have so far not been functionalized to create soft interactive devices, due to a lack of DIY techniques for the fabrication of functional electronic circuits and sensors. In this paper, we contribute a DIY approach for creating Interactive Bioplastics that is accessible to a wide audience, making use of easy-to-obtain bio-based raw materials and familiar tools. We present three types of conductive bioplastic materials and their formulation: sheets, pastes and foams. Our materials enable additive and subtractive fabrication of soft circuits and sensors. Furthermore, we demonstrate how these materials can substitute conventional prototyping materials, be combined with off-the-shelf electronics, and be fed into a sustainable material ‘life-cycle’ including disassembly, re-use, and re-melting of materials. A formal characterization of our conductors highlights that they are even on-par with commercially available carbon-based conductive pastes.