New 'Smart Material' Mimics Sea Urchins
A research team at City University of Hong Kong has developed a new 3D-printed "mechanoelectrical" smart material. The design, inspired by the porous structure of sea urchin spines, could have applications in creating flexible sensors, medical devices, and sound absorption technology.
The research, published in the journal *Nature*, identified that the natural porous ceramic structure of sea urchin spines can generate measurable voltage signals when water flows over them. This response is remarkably fast, occurring within tens of milliseconds, which is over a thousand times faster than the sea urchin's own visual perception. This unexpected mechanoelectrical effect is not tied to any living cells or nerves within the spine. Instead, the phenomenon arises from the spine's intrinsic physical microstructure, a principle confirmed by the fact that the voltage response persists even without any viable cellular tissue. The team, led by Professor Lu Jian at the City University of Hong Kong, analyzed the long-spined sea urchin (*Diadema setosum*) and found its spines have a gradient of pore sizes. This structure creates a differential charge density on the surface as water moves through it, generating what is known as a streaming potential. Using a 3D printing technique called vat photopolymerization, the scientists fabricated artificial structures that mimicked this natural gradient design. The biomimetic versions showed a threefold increase in voltage output and an eightfold increase in signal amplitude compared to similar structures without the gradient design. This breakthrough is a key example of biomimicry, a field of materials science that draws inspiration from nature's solutions to engineer new materials and technologies. Sea urchin spines, in particular, are known for being both lightweight and strong due to their porous, mesh-like internal structure. The development of such 3D-printed smart materials opens the door for new types of flexible, self-powered sensors. Potential future applications include underwater monitoring systems, advanced medical devices, and innovative sound absorption technologies.
