The Onset of Microbubble Vibration

Ultrasound contrast agents : dynamics of coated bubbles

“…A horizontal scan line on the other hand results in the pressuredependent response for different applied frequencies. De facto this is the same experiment as performed by Emmer et al [11] with the exception that Emmer et al varied bubble radius R 0 , not frequency. Such a horizontal scan-line is depicted in Fig.…”

“…Emmer et al [11] showed an oscillation threshold for coated microbubbles with Example of a bubble showing "compression-only" behavior, i.e. the oscillating bubble hardly expands and strongly compresses.…”

“…De Jong et al [10] observed that bubbles compress significantly more than that they expand, which was named "compression-only" behavior. Furthermore it was observed that small bubbles only oscillate above a certain threshold pressure [11]. The origin of this so-called "thresholding" behavior is still unknown.…”

“…Emmer et al [11] investigated the nonlinear dynamics of phospholipid-coated microbubbles R 0 = 1 − 5 µm by increasing the applied acoustic pressure at a constant frequency of 1.7 MHz. They found that a threshold pressure exists, for microbubbles smaller than R 0 = 2 µm, for the onset of bubble oscillations, and that the threshold pressure decreases with increasing bubble size.…”

Combined optical sizing and acoustical characterization of single freely-floating microbubbles

“…25,27 These phenomena were considered not only to be influenced by the resting bubble size, but also to be dependent on the initial surface tension due to the presence of the phospholipid coating, 28,29 which can greatly vary among individual bubbles. 27,30 This explains the variability in the asymmetric response among microbubbles within the same size range, see the two examples (and other bubbles) in Fig.…”