CityUHK research team develops 3D-printed biomimetic "mechanoelectrical" smart materials inspired by sea urchin spines

HONG KONG, March 1, 2026 /PRNewswire/ -- A research team led by Professor Lu Jian, Dean of the College of Engineering and Chair Professor in the Department of Mechanical Engineering at City University of Hong Kong (CityUHK), has discovered that the naturally occurring porous ceramic structure within sea urchin spines possesses an unexpected capability for mechanoelectrical perception.

When water droplets or flows pass over the spine, its gradient cellular structure instantaneously generates measurable voltage signals—a response over a thousand times faster than the organism's visual perception.

The study, titled "Echinoderm stereom gradient structures enable mechanoelectrical perception", was recently published in the prestigious international journal Nature.

Through in situ observations of the long-spined sea urchin (Diadema setosum), researchers found that droplet stimulation induces a transient potential of approximately 100 mV. Crucially, the spines produce this response even without viable cellular tissue, confirming the capability stems from the materia's intrinsic microstructure rather than biological nerves.

Analysis via electron microscopy revealed the spine consists of a bicontinuous porous skeleton, or stereom, with a pronounced pore-size gradient. The apex features smaller pores and a higher specific surface area, which enhances solid–liquid interfacial charge separation. As water moves through these microchannels, it generates a streaming potential, effectively functioning as a natural microscale sensor.

To replicate this, the team used vat photopolymerisation 3D printing to fabricate biomimetic gradient samples. Results showed that these gradient designs exhibited a threefold increase in voltage output and an eightfold increase in signal amplitude compared to gradient-free structures. This proves that perception is governed by topological structure rather than material composition. The team subsequently constructed a biomimetic mechanoreceptor capable of real-time detection of underwater flow intensity without external power.

"Through biomimetic structural design and 3D printing, we have successfully translated nature's wisdom into smart materials," said Professor Lu. "Our goal in fabricating biomimetic functional materials is to extend this structure–function integration concept found in nature into engineered systems, paving the way for a new generation of self-sensing intelligent materials."

This study challenges the view that natural porous structures serve only mechanical functions. These biomimetic structures hold immense potential for marine monitoring, underwater exploration, water management, and aerospace engineering, forming a foundational platform for next-generation of integrated structural/functional materials.