Researchers Create 'Smart Material' from Sea Urchins

The research, published in the journal *Nature*, was led by Professor Lu Jian at the City University of Hong Kong. His team discovered that the porous ceramic structure of sea urchin spines has a natural ability for mechanoelectrical perception. This natural sensing ability is remarkably fast, with a response time more than a thousand times quicker than the sea urchin's own visual perception. When water droplets or flow pass over the spines of the long-spined sea urchin (*Diadema setosum*), they generate a measurable voltage of about 100 mV. This electrical signal is created even without any living tissue, proving the property is intrinsic to the material's structure. The key to this phenomenon is the spine's gradient cellular structure, which has a higher density of smaller pores at its tip. This enhances the separation of charges at the solid-liquid interface as water moves through its microchannels, creating a streaming potential. Using vat photopolymerization, a type of 3D printing, the researchers fabricated a biomimetic version of the sea urchin spine structure. This synthetic version demonstrated a threefold increase in voltage output and an eightfold increase in signal amplitude compared to similar structures without the gradient design. This breakthrough challenges the conventional understanding that natural porous structures mainly serve a mechanical purpose. The new material, which can detect underwater flow direction and intensity in real-time without external power, has potential applications in marine environmental monitoring, underwater exploration, and water resource management.