Sea Urchins Inspire New Smart Material

The research, published in the journal *Nature*, identified that the sea urchin's porous ceramic spine structure can generate measurable voltage signals when disturbed by water droplets or flows. This response is incredibly fast, occurring within tens of milliseconds—over a thousand times faster than the sea urchin's own visual perception. The team, led by Professor Lu Jian from the Department of Mechanical Engineering, studied the long-spined sea urchin (*Diadema setosum*). They discovered that a water droplet could induce a transient potential of about 100 mV. This electrical response is intrinsic to the material's microstructure, functioning even without any living cellular tissue. This natural sensing ability is due to the spine's "stereom," a porous skeleton with a gradient of pore sizes. The smaller pores near the apex create a higher surface area, which enhances charge separation at the solid-liquid interface and generates a streaming potential as water moves through. Using vat photopolymerization 3D printing, the researchers fabricated a biomimetic version. Their artificial structures with a gradient design showed a threefold increase in voltage output and an eightfold increase in signal amplitude compared to non-gradient versions, proving the principle is based on structure, not material composition. This breakthrough opens doors for a new generation of self-sensing intelligent materials. Potential applications include underwater monitoring, marine exploration, water management, and even aerospace engineering, creating a basis for materials with integrated structural and functional properties. The sea urchin has inspired other material science innovations as well. Its skeleton's shape is studied for creating more durable, lightweight architectural panels and even more crack-resistant concrete.