Researchers Create Sea Urchin-Inspired Smart Material

The research, published in the journal *Nature*, identified that the natural porous ceramic structure of sea urchin spines can generate a measurable voltage when water flows over them. This previously unknown "mechanoelectrical" effect is a result of the material's intrinsic microstructure, not any biological or neural tissue. Professor Lu Jian, Dean of the College of Engineering at City University of Hong Kong, led the team in this discovery. Their in-situ observations of the long-spined sea urchin (*Diadema setosum*) showed that a single droplet of seawater could induce a transient potential of approximately 100 millivolts. The spine's remarkable sensitivity comes from its unique structure—a porous skeleton with a gradient of pore sizes. The smaller pores near the apex create a higher surface area, which enhances the electrical charge separation at the solid-liquid interface as water moves through, generating what is known as a streaming potential. This response is incredibly fast, occurring within tens of milliseconds, which is over a thousand times faster than the sea urchin's own visual perception. To replicate this, the team utilized a 3D printing technique called vat photopolymerization to create artificial materials that mimic this natural gradient structure. The engineered biomimetic materials demonstrated a threefold increase in voltage output and an eightfold increase in signal amplitude compared to structures without the gradient design. This proves that the sensing capability is governed by the topological structure rather than the specific material composition. This breakthrough paves the way for a new generation of self-powered, intelligent materials. Potential applications include advanced underwater sensors for real-time monitoring of flow direction and intensity, as well as innovations in marine environmental monitoring, water resource management, and even aerospace engineering.