Acoustic Focusing in Microdroplets

Sammanfattning: This thesis examines the possibility to combine droplet generation techniques together with acoustic particle manipulation in microfluidics to achieve focusing of particles inside micro droplets. In the thesis I introduce the reader to the general concepts of microfluidics, droplet dynamics, acoustics and microfabrication which are the basis for my experiments. The practical work focuses on the important steps in channel design, droplet generation and the possibilities to manipulate polystyrene particles with a diameter 10 _m inside channels with widths of a few hundreds of _m. The particles are manipulated inside water droplets dispersed in an continuous oil phase and the results include an examination of the droplet flow fields in interaction with the primary radiation force. I present evidence that the size and the flow speed of a droplet greatly affects the dynamics of the forces on particles inside the droplets