Division of Biomedical Engineering

The following proposed master’s thesis subjects are all related to our research on acoustic fields in fluids. We study both fundamental aspects and applications of this technology in the area of life science. You will work independently but with frequent interactions with the supervisor in the form of individual meetings as well as project meetings for the overall research project.

An overview of our research relating to acoustofluidics and acoustic cell separation can be found on our research pages.

Do not hesitate to contact Per Augustsson if you have further questions. 

Make acoustofluidic test particles

Acoustofluidics is used to manipulate particles and fluids at the microscale. It can be applied in research and medicine for various purposes. To accurately assess the function of acoustofluidic systems, test particles with known and adjustable properties are needed. To create cell-like particles, giant unilammelar vesicles (GUVs) will be produced through the cDICE method. This method forms droplets by dripping them of a capillary inserted into a running centrifuge. The droplets will subsequently migrate outwards through several layers whereby they acquire a lipid bilayer.

1. Configuration of a cDICE platform based on the results of [Blosser, Soft matter, 2016] and [Abkarian, Soft matter, 2011].
2. Microscopic investigation of droplet formation with a stroboscope.
3. Particle characterization by microscopy, density, and speed-of-sound measurements

Sorting particles and cells by their density

Physical properties like mass, volume, and density are highly integrative metrics for the state of a cell. Cells can be sorted by density in bulk or in microfluidics, but each method has its specific advantages and disadvantages. Particles can be separated by density with continuous-gradient density centrifugation whereby each particle will end up surrounded by medium with the same density. By extraction of the particle-medium suspension the particles density can be determined by measuring the density of the medium.

1. Implementation of a method for creating continuous density gradients for separation of particles/cells.
2. Evaluation of methods to measure fluid density and implementation of one of them.
3. Build a device that can extract particles/cells and medium out of a density gradient, with following measurement of the medium density.

Study acoustic streaming in non-Newtonian liquids

Acoustic streaming is a steady mixing of a fluid associated with the attenuation of a sound field due to the presence of for instance a boundary. This streaming is the major limiting factor when focusing small particles by acoustic fields and therefore we are looking into different ways to suppress acoustic streaming. It has been hypothesized that the acoustic streaming field is drastically affected for fluids that are non-Newtonian, i.e. that has the property that the viscosity is a function of the applied stress. One example of such a fluid is corn starch dissolved in water which is a liquid under low stress conditions but that can solidify upon a sudden impact. Another (annoying) example is ketchup, that sticks to the walls of the bottle for some time until it suddenly rushes out once it is set in motion.   

 In this project you will investigate acoustic streaming in non-Newtonian fluids.

1. Apply a method to track particles in 3 dimensions in a microscope to map the acoustic streaming field.
2. Measure the viscoelastic properties of candidate fluids.
3. Compare the acoustic streaming field for candidate fluids and compare to theoretical simulations.