Hong Kong Researchers Develop 3D-Printed Biomimetic Sensors Inspired By Sea Urchin Spine Mechanoelectrical Perception

PolyU researchers use sea urchin spine structures to create 3D-printed, self-powered sensors for underwater monitoring and brain-computer interfaces.

By: AXL Media

Published: Mar 21, 2026, 7:07 AM EDT

Source: Information for this report was sourced from The Hong Kong Polytechnic University

Uncovering Nature's Hidden Aquatic Sensors

New research led by Professor Wang Zuankai at The Hong Kong Polytechnic University has revealed that sea urchin spines serve as sophisticated mechanoelectrical sensors rather than purely defensive tools. The study, published in the journal Nature, found that the long-spined sea urchin uses a gradient porous internal skeleton to instantly detect changes in water flow. When stimulated by seawater, these spines generate measurable voltages reaching up to 100 millivolts. Crucially, the researchers observed this phenomenon even in non-living spines, proving that the sensing capability is a result of the physical structure rather than biological cellular activity.

The Physics Of Gradient Porous Structures

The secret to this sensing ability lies in the "stereom" structure of the spine, which features a bicontinuous gradient of pores that shift in size from the base to the tip. According to the research team, as water moves through these varying pores, it creates a shear force against the electric double layer at the solid-liquid interface. This interaction induces a separation of charges, generating a voltage difference across the spine. The gradient design significantly intensifies this effect, allowing the spine to act as a highly sensitive, self-powered flow meter that functions effectively in high-pressure underwater environments.

Replicating Biological Designs With 3D Printing

To validate their findings, the scientists utilized vat photopolymerization 3D printing to create artificial polymer and ceramic replicas of the sea urchin’s internal architecture. These biomimetic samples demonstrated a voltage output three times higher than traditional, non-gradient designs when exposed to identical water flow conditions. Professor Wang noted that this proves the sensing mechanism is material-independent, relying instead on the geometric arrangement of the pores. This flexibility allows engineers to choose materials based on the specific needs of an industry, such as corrosion resistance for marine use or lightweight properties for aerospace applications.