Researchers 3D-Print Smart Material Inspired by Sea Urchins

The research, led by Professor Lu Jian at the City University of Hong Kong, was published in the journal *Nature* and delved into the properties of the long-spined sea urchin, *Diadema setosum*. The team discovered that the urchin's spines, which are essentially porous ceramic structures, can generate a measurable voltage signal from the movement of water over their surface. This response is remarkably fast, occurring within tens of milliseconds. This "mechanoelectrical" effect is not biological; it stems from the material's intrinsic physical structure. The spines have a gradient cellular structure with smaller pores near the apex, which enhances the separation of charges at the solid-liquid interface as water flows through. This process generates what is known as a streaming potential, effectively turning the spine into a natural micro-sensor. To mimic this, the scientists used a 3D-printing technique called vat photopolymerization. They successfully replicated the gradient porous design of the sea urchin spine in a new ceramic material. This biomimetic approach is a growing field that seeks to solve complex human problems by imitating nature's designs and processes. The 3D-printed replicas demonstrated a significant performance boost, showing a threefold increase in voltage output and an eightfold increase in signal amplitude compared to similar structures without the gradient design. This confirmed that the sensing capability is primarily governed by the material's topological structure rather than its chemical composition. This new material can detect the direction and intensity of underwater flows in real-time without needing any external power source or sensors. Potential applications are vast, ranging from marine environmental monitoring and intelligent underwater exploration to new types of biomedical devices and aerospace engineering.