We describe a manufacturing process to 3D print engineered materials comprised of a userspecified pattern of nano-or microparticles embedded in a polymer matrix material. The materials This article is protected by copyright. All rights reserved.2 are printed layer-by-layer using stereolithography, and in each layer we employ ultrasound directed self-assembly to organize a user-specified pattern of particles. This process allows manufacturing macroscale 3D materials with a user-specified microstructure consisting of particles of any material, and contrasts with existing processes, which are often limited to laboratory scale, specific materials, and/or 2D implementations. Using this manufacturing process, we demonstrate 3D printing of macroscale multi-layer engineered materials containing a Bouligand microstructure commonly found in composite laminate and biological materials. Additionally, we fabricate engineered materials containing a pattern of electrically conductive nickel-coated carbon fibers, which illustrates the feasibility of 3D printing structures with embedded insulated electrical wiring. This process finds application in manufacturing of multifunctional composite materials.

We use ultrasound directed self-assembly to organize particles dispersed in a fluid medium into a three-dimensional (3D) user-specified pattern. The technique employs ultrasound transducers that line the boundary of a fluid reservoir to create a standing ultrasound wave field. The acoustic radiation force associated with the wave field drives particles dispersed in the fluid medium into organized patterns, assuming that the particles are much smaller than the wavelength and do not interact with each other. We have theoretically derived a direct solution method to calculate the ultrasound transducer operating parameters that are required to assemble a user-specified 3D pattern of particles in a fluid reservoir of arbitrary geometry. We formulate the direct solution method as a constrained optimization problem that reduces to eigendecomposition. We experimentally validate the solution method by assembling 3D patterns of carbon nanoparticles in a water reservoir and observe good quantitative agreement between theory and experiment. Additionally, we demonstrate the versatility of the solution method by simulating ultrasound directed self-assembly of complex 3D patterns of particles. The method works for any 3D simple, closed fluid reservoir geometry in combination with any arrangement of ultrasound transducers and enables employing ultrasound directed self-assembly in a myriad of engineering applications, including biomedical and materials fabrication processes.

We employ an ultrasound wave field generated by one or more ultrasound transducers to organize large quantities of nanoparticles dispersed in a fluid medium into two-dimensional user-specified patterns. To accomplish this, we theoretically derive a direct method of calculating the ultrasound transducer parameters required to assemble a user-specified pattern of nanoparticles. The computation relates the ultrasound wave field and the force acting on the nanoparticles to the ultrasound transducer parameters by solving a constrained optimization problem. We experimentally demonstrate this method for carbon nanoparticles in a water reservoir and observe good agreement between experiment and theory. This method works for any simply closed fluid reservoir geometry and any arrangement of ultrasound transducers, and it enables using ultrasound directed self-assembly as a scalable fabrication technique that may facilitate a myriad of engineering applications, including fabricating engineered materials with patterns of nanoscale inclusions.

A method of unconstrained and continuous manipulation of micro-particles in a fluid using bulk acoustic waves is theoretically derived and experimentally demonstrated. The method is based on phase-control of standing pressure waves created by two opposing transducers. Reflections are taken into account, removing the need for complex experiments. The operating domain of this method is characterized and compared to existing techniques. In contrast to methods based on linearly adjusting the phase difference between opposing transducers, it is shown that by independently controlling the phase of each transducer, particles can be manipulated in an unconstrained manner over multiple wavelengths. V

We employ an ultrasound wave field generated by one or more ultrasound transducers to organize large quantities of nanoparticles dispersed in a fluid medium into two-dimensional user-specified patterns. To accomplish this, we theoretically derive a direct method of calculating the ultrasound transducer parameters required to assemble a user-specified pattern of nanoparticles. The computation relates the ultrasound wave field and the force acting on the nanoparticles to the ultrasound transducer parameters by solving a constrained optimization problem. We experimentally demonstrate this method for carbon nanoparticles in a water reservoir and observe good agreement between experiment and theory. This method works for any simply closed fluid reservoir geometry and any arrangement of ultrasound transducers, and it enables using ultrasound directed self-assembly as a scalable fabrication technique that may facilitate a myriad of engineering applications, including fabricating engineered materials with patterns of nanoscale inclusions. V