Ultrasound Noncontact Particle Manipulation of Three-dimensional Dynamic User-specified Patterns of Particles in Air

Ultrasound noncontact particle manipulation (NPM) is based on the acoustic radiation force associated with an ultrasound wave field, and enables a myriad of engineering applications with the ability to noninvasively manipulate particles in a fluid medium. We use multiple phased arrays of ultrasound transducers to dynamically move a 3D pattern of particles along a user-specified trajectory following a sequence of affine transformations. We numerically simulate and experimentally validate the NPM method using spherical expanded polystyrene particles in air, and observe good quantitative agreement. The ultrasound NPM method enables dynamic control over the user-specified pattern of particles in three dimensions. Hence, this experimental demonstration shows that ultrasound NPM can be implemented in engineering applications, such as containerless transport and measurement techniques, and manufacturing of engineered materials.