Fergal Brian Coulter

Microbially induced-calcium carbonate precipitation (MICP) offers a less energy-intensive alternative to conventionally manufactured binders by enabling mineral formation through microbial activity. However, its architectural applications remain limited, confined to static, mold-based approaches or soil engineering contexts, which lack adequate manufacturing and geometric control methods for architectural applications. Here we present Robotic Biocementation Spraying (RBS), a bio-inspired fabrication method that couples biological intelligence with robotic precision to achieve continuous biomineralization across architectural surfaces. Inspired by the cyclic processes of stromatolite formation, RBS alternates between biological activation and mineral deposition using a multi-material robotic spray system. The system deposits Sporosarcina pasteurii , combined with polymeric agents and sand granules, to create cohesive biocemented layers through in situ microbial activity. Fabrication parameters such as toolpath spacing, nozzle configuration, deposition sequence, and spray exposure regulate material accumulation and surface development. The method was evaluated through quantitative material assays, mesoscale experiments, and prototypes, followed by a full-scale demonstrator. RBS produced consistent calcium carbonate formation with CaCO ₃ contents ranging from 76.9% to 86.0% and spatial variation within ±10%–15%, and stable material buildup across complex geometries under ambient conditions. Robotic control allowed spatial variation in material accumulation and surface thickness through differentiated spray trajectories. The full-scale demonstrator (1.2 × 0.5 m) operated continuously over an extended fabrication period, sustaining mineral growth, achieving maximum vertical buildup of 24 cm and the fabrication of more than one cubic meter of biocemented material. RBS establishes a programmable biofabrication framework in which microbial mineralization is coordinated through robotic sequencing. This integration of biological activity and digital fabrication reframes mineral matter as a biologically cultivated material system for architectural applications, extending MICP beyond laboratory and geotechnical contexts toward scalable biogenic surface fabrication.

Self‐healing silicones that are able to restore functionalities and extend the lifetime of soft devices hold great potential in many applications. However, currently available silicones need to be triggered to self‐heal or suffer from creep‐induced irreversible deformation during use. Here, a platform is proposed to design and print silicone objects that are programmed at the molecular and architecture levels to achieve self‐healing at room temperature while simultaneously resisting creep. At the molecular scale, dioxaborolanes moieties are incorporated into silicones to synthesize self‐healing vitrimers, whereas conventional covalent bonds are exploited to make creep‐resistant elastomers. When combined into architectured printed parts at a coarser length scale, the layered materials exhibit fast healing at room temperature without compromising the elastic recovery obtained from covalent polymer networks. A patient‐specific vascular phantom and fluidic chambers are printed to demonstrate the potential of architectured silicones in creating damage‐resilient functional devices using molecularly designed elastomer materials.

Structural color is frequently exploited by living organisms for biological functions and has also been translated into synthetic materials as a more durable and less hazardous alternative to conventional pigments. Additive manufacturing approaches were recently exploited for the fabrication of exquisite photonic objects, but the angle-dependence observed limits a broader application of structural color in synthetic systems. Here, we propose a manufacturing platform for the 3D printing of complex-shaped objects that display isotropic structural color generated from photonic colloidal glasses. Structurally colored objects are printed from aqueous colloidal inks containing monodisperse silica particles, carbon black, and a gel-forming copolymer. Rheology and Small-Angle-X-Ray-Scattering measurements are performed to identify the processing conditions leading to printed objects with tunable structural colors. Multimaterial printing is eventually used to create complex-shaped objects with multiple structural colors using silica and carbon as abundant and sustainable building blocks.

Benchtop testing of endovascular medical devices under accurately simulated physiological conditions is a critical part of device evaluation prior to clinical assessment. Currently, glass, acrylic and silicone vascular models are predominantly used as anatomical simulator test beds for in vitro testing. However, most current models lack the ability to mimic the non-linear radial compliance of native vessels and are typically limited to being compliance-matched at a single mean pressure comparison point or not at all. Hence, a degree of caution needs to be shown when analysing results from such models under simulated physiological or pathophysiological conditions. Similarly, the clinical translation of proposed biomimetic compliance-matched vascular grafts has undoubtedly been curtailed due to performance and material limitations. Here, we propose a new design for synthetic vessels where compliance can be precisely modulated across a wide physiological pressure range by customising design parameters. Building on previously demonstrated methods of 3D printing composite compliant cylindrical structures, we demonstrate proof of principle in creating composite vascular constructs designed via a finite element model. Our constructs are 3D printable and consist of a soft silicone matrix with embedded polyurethane fibres. The fibre layer consists of circumferential sinusoidal waves with an amplitude that can be altered to result in tuneable internal radial compliances of 5.2–15.9%/mmHg × 10⁻² at a mean pressure of 100 mmHg. Importantly, the design presented here allows preservation of the non-linear exponentially decaying compliance curve of native arteries and veins with an increasing mean pressure. This model offers a design toolbox for 3D printable vascular models that offer biomimetic compliance. The robust nature of this model will lead to rapidly accelerating the design process for biomimetic vascular anatomical simulators, lumped parameter model flow loops, endovascular device benchtop testbeds, and compliance-matched synthetic grafts.

Customized bioresorbable airway stents with elasticity similar to silicone were 3D printed by digital light processing.

Soft actuation allows robots to interact safely with humans, other machines, and their surroundings. Full exploitation of the potential of soft actuators has, however, been hindered by the lack of simple manufacturing routes to generate multimaterial parts with intricate shapes and architectures. Here, we report a 3D printing platform for the seamless digital fabrication of pneumatic silicone actuators exhibiting programmable bioinspired architectures and motions. The actuators comprise an elastomeric body whose surface is decorated with reinforcing stripes at a well-defined lead angle. Similar to the fibrous architectures found in muscular hydrostats, the lead angle can be altered to achieve elongation, contraction, or twisting motions. Using a quantitative model based on lamination theory, we establish design principles for the digital fabrication of silicone-based soft actuators whose functional response is programmed within the material's properties and architecture. Exploring such programmability enables 3D printing of a broad range of soft morphing structures.

3D printing of bacteria-laden hydrogels enables the digital fabrication of complex functional materials.