Scientists Create Smart Material from Sea Urchins
A research team at City University of Hong Kong has developed a new 3D-printed "mechanoelectrical" smart material. The design was inspired by the porous structure of sea urchin spines, which naturally convert mechanical force into electrical signals.
The research, published in the journal *Nature*, was led by Professor Lu Jian, Dean of the College of Engineering at City University of Hong Kong. His team studied the long-spined sea urchin (*Diadema setosum*) and discovered its porous ceramic spines could generate a measurable voltage of about 100 mV when stimulated by water droplets. This electrical response is remarkably fast, occurring within tens of milliseconds—over a thousand times quicker than the sea urchin's own visual perception. Crucially, the team confirmed this is an intrinsic property of the spine's physical microstructure, as the voltage is generated even without any living biological tissue. The secret lies in the spine's internal structure, a porous skeleton with a gradient of pore sizes. As water flows through these microchannels, it creates what is known as a streaming potential, effectively turning the natural spine into a micro-scale sensor. Using a 3D printing technique called vat photopolymerization, the scientists replicated this gradient structure. Their biomimetic version showed a threefold increase in voltage output and an eightfold increase in signal amplitude compared to similar structures without the size gradient, proving the effect is governed by the architecture, not the material itself. This breakthrough challenges the conventional view that natural porous structures mainly serve mechanical functions, revealing their hidden sensing capabilities. The team successfully built a biomimetic mechanoreceptor that can detect underwater flow intensity and direction in real-time without needing any external power source. Potential applications for this self-powered smart material are vast. They include marine environmental monitoring, intelligent underwater exploration, water resource management, and even aerospace engineering.
