Microstructural Control via Acoustic Assembly for Complex Functionalities in Composites

Control of the microscale distribution of phases in composite materials enables spatial modulation and amplification of functional properties within a component. A promising method for dynamically ordering microstructure is acoustic focusing, in which microparticles suspended in a fluid are manipulated with pressure fields generated by piezoelectric actuation within a microfluidic device. With this method we assemble functional particles into structures with tunable microstructural features, which we then freeze within a second phase or deposit onto a substrate as a curable ink for printing components with complex functionalities. The process is largely material agnostic, allowing the patterning of a wide variety of functional microparticles within various fluid media. We use confocal microscopy to pinpoint assembly regimes for structures with controlled particle distributions, particle alignment, and anisotropic packing density modulated spatially throughout components. We demonstrate the feasibility of this method by patterning networks of conductive particles cured in resins to measure thermal and electrical conductivity of the resulting composites.