Injection rate control on the growth direction in chemical gardens

The spontaneous organization of inorganic structures holds potential for applications in biomimetic material design. In this study, tubular precipitation structures were produced by injecting an aqueous solution of copper chloride into an aqueous solution of sodium silicate within an upright Hele-Shaw cell. The direction of tube growth, either upward or lateral, depended on the injection rate. The mechanism for selecting the growth direction and its bifurcation was examined in relation to factors such as the injection rate, water penetration, and the density differences between the two reactive solutions. This investigation contributes to the understanding of controlled inorganic spontaneous organization. It paves the way for diverse and autonomous growth in response to their environmental conditions, akin to plant growth or vascular formation in living organisms.