Researchers Create Smart Material Inspired by Sea Urchins
A research team at City University of Hong Kong has developed a new 3D-printed smart material by mimicking the structure of sea urchin spines. The resulting biomimetic material exhibits unique "mechanoelectrical" properties, converting mechanical stress into electrical signals, which could have applications in advanced sensors and robotics.
The research, led by Professor Lu Jian at the City University of Hong Kong, was published in the journal *Nature*. His team's work focused on the long-spined sea urchin, *Diadema setosum*, uncovering that its spines can inherently convert motion into electricity. This electrical response is surprisingly rapid, occurring within tens of milliseconds and over a thousand times faster than the sea urchin's own visual perception. When a water droplet hits the spine, it generates a transient potential of about 100 millivolts. This capability is not biological; it originates from the material's physical microstructure, as the response persists even without any living tissue. The secret lies in the spine's natural porous ceramic structure, which has a gradient of pore sizes. As water flows through these microchannels, an electric double layer is created at the solid-liquid interface, generating what is known as a streaming potential—a measurable voltage signal. This effectively makes the spine a natural micro-sensor. Using a 3D printing technique called vat photopolymerization, the researchers fabricated artificial structures that mimicked the sea urchin spine's gradient porosity. The 3D-printed versions, made from polymers and ceramics, showed a threefold increase in voltage output and an eightfold increase in signal amplitude compared to structures printed without the gradient design. This breakthrough proves that the sensing capability is determined by the structure's topology, not just the material it's made from. The team has already built a biomimetic mechanoreceptor that can detect underwater flow intensity in real-time without needing an external power source. Beyond underwater applications, this nature-inspired design holds potential for advancements in marine environmental monitoring, water resource management, and even biomedical devices. The work challenges the conventional view that natural porous structures are purely for mechanical support, revealing their latent sensing functions.
