Researchers Create Smart Material Inspired by Sea Urchins
A research team at City University of Hong Kong has developed a new 3D-printed "mechanoelectrical" smart material by mimicking the structure of sea urchin spines. The biomimetic design is porous and shock-absorbing, with potential applications in flexible electronics and advanced sensors.
The research, led by Professor Lu Jian, Dean of the College of Engineering at City University of Hong Kong, was recently published in the scientific journal *Nature*. His team discovered that the porous ceramic structure within the spines of the long-spined sea urchin (*Diadema setosum*) has a natural ability for mechanoelectrical sensing. 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 a water droplet hits the spine, it generates a measurable voltage of about 100 mV. This electrical signal is created by the movement of water through the spine's unique microchannels, a phenomenon known as streaming potential. Sea urchin spines are composed of a porous, mesh-like microstructure called a stereom, which makes them both lightweight and strong. This intricate structure consists of a highly oriented array of Mg-calcite nanocrystals. The CityUHK team found that even without any living cellular tissue, the spines still produced a voltage response, proving the capability is intrinsic to the material's physical structure. Using a 3D printing technique called vat photopolymerization, the researchers were able to replicate this complex architecture. Their biomimetic designs showed a threefold increase in voltage output and an eightfold increase in signal amplitude compared to structures without the sea urchin-inspired gradient. This breakthrough demonstrates that the mechanoelectrical properties are governed by the material's topological structure rather than its composition. The team constructed a prototype mechanoreceptor that can detect the direction and intensity of underwater flows in real-time without needing an external power source. The potential applications for this new smart material are extensive, ranging from marine environmental monitoring and underwater exploration to biomedical devices and aerospace engineering. It lays the groundwork for a new class of self-sensing intelligent materials.
