Controlled growth and form of precipitating microsculptures

A geometrical theory explains the three-dimensional growth and complex form of carbonate-silica precipitates. Predicting the shape of crystals to come Coprecipitating carbonate and silica can form complex three-dimensional shapes. These range from flowers to trumpets, depending on the pH. Kaplan et al. developed a theoretical model to interpret the crystal growth shapes. The model predicts crystal growth shapes under varying experimental conditions and captures the geometrical aspects of morphological development. Science, this issue p. 1395 Controlled self-assembly of three-dimensional shapes holds great potential for fabrication of functional materials. Their practical realization requires a theoretical framework to quantify and guide the dynamic sculpting of the curved structures that often arise in accretive mineralization. Motivated by a variety of bioinspired coprecipitation patterns of carbonate and silica, we develop a geometrical theory for the kinetics of the growth front that leaves behind thin-walled complex structures. Our theory explains the range of previously observed experimental patterns and, in addition, predicts unexplored assembly pathways. This allows us to design a number of functional base shapes of optical microstructures, which we synthesize to demonstrate their light-guiding capabilities. Overall, our framework provides a way to understand and control the growth and form of functional precipitating microsculptures.