Motivation:

Three-dimensional contactless assembly of micro-objects (and organisms) holds great promise within microfluidics and organs-on-a-chip technology. Most commonly such manipulation is achieved by optical traps, which are expensive and not always fully biocompatible as the strong focused laser beams can damage the sample. In recent years Acoustophoresis, i.e. the contactless manipulation of particles or cells by acoustic waves, has been proposed as a non-invasive alternative to optical tweezers. Although, vortex beams can be regarded as the most promising acoustic analogue to the optical tweezers many questions remain open. A recent (theoretical) study [1] suggested that vortex beams may be used for the 3D trapping and assembly of particles.

Goal:

The goal of this master’s thesis is to expand the previous analysis by performing a multibody dynamics simulation of the suggested assembly process. The simulation will consider contact forces, as well as hydrodynamic and acoustic particle interaction and therefore provide further grounds for the feasibility of the suggested technology. In a first step the acoustic forces will be considered for a special case and modelled analytically. In a second step the assumptions will be dropped, and the scattering problem will be solved by the finite-element method.

Workflow:

A particle dynamics model developed by the thesis main supervisor [2, 3] will be provided to the student. The student will expand the model to incorporate vortex beams and apply the cases suggested in [1]. The student will then perform a theoretical and numerical assessment of the technology presented in [1].

Transferable skills:

The thesis allows a mathematically inclined student to investigate a state-of-the art technology theoretically. The skillset required for the project spans several topics in classical mechanics and numerical methods. The project is therefore an excellent opportunity to take on a challenging topic and gain further practical experience in applying theoretical knowledge to research related challenges.

Topics:

Wave-motion, theoretical analysis and numerical modelling, Matlab, Non-linear acoustics, Lagrangian mechanics, non-smooth mechanics, Stokesian dynamics, scattering.
If you are interested in joining this project or if you would like more information, please contact Thierry Baasch at Thierry.Baasch@bme.lth.se.

[1] Gong, Zhixiong, and Michael Baudoin. "Three-dimensional trapping and assembly of small particles with synchronized spherical acoustical vortices." Physical Review Applied 14.6 (2020): 064002.
[1] Baasch, Thierry, Ivo Leibacher, and Jürg Dual. "Multibody dynamics in acoustophoresis." The Journal of the Acoustical Society of America 141.3 (2017): 1664-1674.
[2] Baasch, Thierry, and Jürg Dual. "Acoustofluidic particle dynamics: Beyond the Rayleigh limit." The Journal of the Acoustical Society of America 143.1 (2018): 509-519.