MIT engineers are using filter structures inspired by manta rays to develop more efficient water treatment systems using 3D printing. This makes it possible to achieve an optimum balance between flow rate and particle separation. This also reduces energy requirements without sacrificing performance. This reduces costs.
Mobula rays use parallel plates in their mouths to efficiently filter plankton from water currents. As water flows through the gills, special geometries create vortices that direct particles into the ray’s body without interfering with water flow or respiration. This concept inspired the researchers to develop a filter system based on similar principles.
“We show that the mobula ray has evolved the geometry of these plates to be the perfect size to balance feeding and breathing,” says study author Anette “Peko” Hosoi, the Pappalardo Professor of Mechanical Engineering at MIT.
“We want to expand the design space of traditional cross-flow filtration with new knowledge from the manta ray,” says lead author and MIT postdoc Xinyu Mao PhD ’24. “People can choose a parameter regime of the mobula ray so they could potentially improve overall filter performance.”
The team printed 3D models of the plate structures and used them to build a so-called “leak channel”, a transparent channel with small openings. At slow water flows, the plates allowed particles and water to pass through, while at higher speeds, vortices were created that effectively blocked particles and directed them into the waste stream. This property could improve conventional filter designs by optimally combining permeability and selectivity.
The research team created a design manual that shows how industrial filters can be optimized using the mobula-like structure. The aim is to make filtration processes in areas such as water treatment or medical technology more efficient.
“You want to design a filter such that you’re in the regime where you generate vortices,” Hosoi says. “Our guidelines tell you: If you want your plant to pump at a certain rate, then your filter has to have a particular pore diameter and spacing to generate vortices that will filter out particles of this size. The mobula ray is giving us a really nice rule of thumb for rational design.”
This work, supported by the U.S. National Institutes of Health, shows how nature and technology can be combined to solve industrial challenges.
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