Robotic biocementation spraying: a bioinspired fabrication method for architectural surfaces

Abstract 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.