Research

Assembling material building blocks into rationally designed structures can lead to novel functionalities and unprecedented performances in energy and composite materials. Existing methods to assemble materials rely on the materials’ electrical, magnetic, or chemical properties, which greatly limit their general applicability to a wide range of materials. We developed an acoustic-assisted material assembly method that puts fewer restrictions on the materials' physical or chemical properties than existing methods. This method only requires a density difference between the materials to be assembled and their surrounding media. The method has been successfully used to assemble particles with sizes ranging from nanometers to millimeters when dispersed in low-viscosity solvents or highly viscous polymer solutions. We designed and manufactured a bio-inspired surface composite structure using the acoustic-assisted method. This structure mimics the exoskeleton of Namib Desert Beetles, with hydrophilic aluminum “bumps” distributed across a hydrophobic polymer substrate. By controlling the acoustic frequency, the density of the hydrophilic bumps on the substrate can be modulated to achieve excellent efficiency for harvesting water from humid air. The acoustic-assisted method was also used to assemble battery electrode materials into ordered 3D structures, such as aligned channels and checkerboard patterns. These structures greatly improve the electrodes’ cycle life and their ability to retain capacity at high charge/discharge rates, compared to conventional electrodes with no ordered structures.

Supported by National Science Foundation CAREER award and Advanced Manufacturing.