A team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has developed a novel metallic surface material that repels water and can stay dry underwater for months. Inspired by the diving bell spider, the surface material greatly resists adhesion by bacteria and marine organisms like barnacles. The researchers believe that the surface has potential applications in various fields.
The diving bell spider, also known as Argyroneta aquatica, is the only species of spider that lives almost entirely underwater. It has millions of rough, water-repellant hairs that create an oxygen reservoir around its body, acting as a barrier between its lungs and water. The thin layer of air trapped by the spider’s hair is called a plastron.
In theory, researchers have known for decades that a stable, underwater plastron is possible. However, creating a rough surface like the diving bell spider’s has been challenging due to mechanical weakness and sensitivity to temperature and pressure changes. Previous experiments have shown that surfaces only remained dry for a few hours.
To overcome these challenges, the researchers developed an aerophilic titanium alloy surface that attracts and sheds bubbles of air or gas. They created nanoscale roughness using electrochemical oxidation to form an oxide layer and then chemically dissolved the formed oxide.
The stability of the surface was tested by subjecting it to bending, twisting, hot and cold water blasts, and abrasions with sand and steel. The surface remained aerophilic and survived over 208 days of continuous submersion in water without degradation. It also significantly reduced the growth of E. coli bacteria and barnacles, and prevented mussels from adhering altogether.
The researchers believe that the surface has wide-ranging practical applications. It can be used on biomedical devices to reduce post-operative infections and prevent corrosion in underwater pipelines and sensors. It can also be combined with another bioinspired material called Slippery Liquid-Infused Porous Surfaces (SLIPS), which was developed by the same team over 10 years ago.
The team is excited about the stability, simplicity, and scalability of the surface material. They believe that the characterization approach used in this study provides a toolkit for optimizing superhydrophobic surfaces in various applications.
The study was published in the journal Nature Materials. Videos produced by SEAS demonstrate how the novel surface repels water and blood.
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1. Source: Coherent Market Insights, Public sources, Desk research
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