FIG. 2.

(Color online) An example of the data analysis performed on individual microbubble radius-time curves in order to obtain the relative fundamental oscillation amplitude ($A_{\mathit{f}\mathit{u}\mathit{n}}$). (a) The raw normalized radius versus time curve $(R/R_0)$ and (c) its Fourier transform as extracted from an ultrafast frame rate microscopy recording of a 3.7 μm diameter microbubble in a 1 cP solution. After applying a band-pass filter around the transmit frequency (1 MHz), panels (b) and (d) illustrate the resulting time and frequency domain representation; namely the radial oscillations at the fundamental frequency $R_{\mathit{f}\mathit{u}\mathit{n}}$. The amplitude of this function is defined as the relative fundamental oscillation amplitude $A_{\mathit{f}\mathit{u}\mathit{n}}$.