#Hong Kong #CityUHK #biomimetic #mechanoelectrical

Innovative Biomimetic Materials Inspired by Nature

In an exciting development in the realm of materials science, a remarkable team of researchers at the City University of Hong Kong (CityUHK) has unveiled a groundbreaking study that centers around the creation of 3D-printed biomimetic materials. The inspiration? The extraordinary spines of sea urchins, which are now being recognized for their mechanoelectrical properties.

The Discovery

Led by Professor Lu Jian, the Dean of the College of Engineering and a Chair Professor in Mechanical Engineering, the research has identified that the unique porous ceramic structure inherent in sea urchin spines not only serves a mechanical purpose but also possesses a remarkable ability to perceive mechanical stimuli through an electrical response. This phenomenon occurs when water flows or droplets interact with the spine, leading to the rapid generation of electrical voltage signals—over a thousand times faster than how these organisms respond visually.

The study, published in the eminent journal Nature, details their findings from the long-spined sea urchin (Diadema setosum). Remarkably, it was observed that stimulation by water droplets can induce a transient potential of about 100 mV, showcasing this response irrespective of viable cellular tissue. Hence, the research demonstrates that the capability stems from the intricate microstructure within the material rather than from biological nerve signals.

Understanding the Mechanism

Through detailed analysis using electron microscopy, researchers uncovered that the spine is composed of a bicontinuous porous skeleton, known as stereom, characterized by a unique pore-size gradient. In particular, the apex of the spine exhibits smaller pores, enhancing interaction between solid and liquid phases, which boosts charge separation. As water navigates through these microchannels, a streaming potential is generated, allowing the spine to act as a natural microscale sensor—a feature that has tremendous potential applications.

Bridging Nature and Engineering

To mimic this extraordinary natural mechanism, the research team employed vat photopolymerisation 3D printing techniques. The results were astounding: the biomimetic gradient samples exhibited a threefold increase in voltage output and an eightfold surge in signal amplitude when compared to structures devoid of such gradients. This unequivocally highlights that the perception is engineered via topological structures rather than merely material composition.

Building on this discovery, the team proceeded to construct a biomimetic mechanoreceptor adept at detecting underwater flow intensity in real-time, without requiring external power sources.