Relationship between size and frequency dependent attenuation of monodisperse populations of lipid coated microbubbles

AbstractAcoustic techniques were employed to investigate the relationship between the mean size of monodispersions of lipid coated microbubbles and frequency dependent attenuation. Flow focusing microfluidic devices were constructed to produce several populations of monodisperse lipid coated microbubbles (i.e. with narrow size distribution). The mean diameter of each population was controlled by selecting the appropriate gas pressure and flowrate of the lipid solution through the device. Using this approach, monodispersions of lipid coated microbubbles were produced with mean diameters ranging from 3·3 to 8·3 μm. Using an acoustic spectroscopy technique, the frequency dependent attenuation coefficient for suspensions of lipid coated microbubbles was measured as a function of mean diameter. These results show that the width and peak magnitude of the attenuation spectrum depended upon the width of the microbubble size distribution (i.e. monodispersions versus polydispersions). Furthermore, as the mean size ...