Michel Versluis

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The main constituent of an ultrasound contrast agent (UCA) is gas-filled microbubbles. An average UCA contains billions per ml. These microbubbles are excellent ultrasound scatterers due to their high compressibility. In an ultrasound field they act as resonant systems, resulting in harmonic energy in the backscattered ultrasound signal, such as energy at(More)
A new optical characterization of the behavior of single ultrasound contrast bubbles is presented. The method consists of insonifying individual bubbles several times successively sweeping the applied frequency, and to record movies of the bubble response up to 25 million frames/s with an ultrahigh speed camera operated in a segmented mode. The method,(More)
The snapping shrimp (Alpheus heterochaelis) produces a loud snapping sound by an extremely rapid closure of its snapper claw. One of the effects of the snapping is to stun or kill prey animals. During the rapid snapper claw closure, a high-velocity water jet is emitted from the claw with a speed exceeding cavitation conditions. Hydrophone measurements in(More)
Ultrasound contrast microbubbles have the ability to enhance endothelial cell permeability and thus may be used as a new way to deliver drugs. It facilitates the transfer of extracellular molecules into cells activated through ultrasound driven microbubbles. The present study is designed to correlate the relationship between microbubble induced cell(More)
The altered iron concentration in many neurodegenerative diseases such as Alzheimer's disease (AD) has led to the development of MRI sequences that are sensitive to the accompanying changes in the transverse relaxation rate. Heavily T(2)*-weighted imaging sequences at high magnetic field strength (7T and above), in particular, show potential for detecting(More)
The influence of the stabilizing phospholipid-coating on the nonlinear dynamics of ultrasound contrast agent microbubbles is investigated. We record the radial dynamics of individual microbubbles with an ultra high-speed camera as a function of both driving pressure and frequency. The viscoelastic shell was found to enhance the nonlinear bubble response at(More)
Very fine sand is prepared in a well-defined and fully decompactified state by letting gas bubble through it. After turning off the gas stream, a steel ball is dropped on the sand. On impact of the ball, sand is blown away in all directions ("splash") and an impact crater forms. When this cavity collapses, a granular jet emerges and is driven straight into(More)
The fluid dynamic interaction of cavitation bubbles with adherent cells on a substrate is experimentally investigated. We find that the nonspherical collapse of bubbles near to the boundary is responsible for cell detachment. High-speed photography reveals that a wall bounded flow leads to the detachment of cells. Cells at the edge of the circular area of(More)
Ultrasound contrast agents are now available since a few years and used for diagnostic purposes. Improved diagnostic decisions have been made possible with new imaging methods that are mainly based on the nonlinear properties of gas microbubbles. Since it is well known that contrast agents are destroyed by ultrasound when the acoustic pressure exceeds a(More)
Ultrasound (US) in combination with contrast microbubbles has been shown to alter the permeability of cell membranes without affecting cell viability. This permeabilisation feature is used to design new drug delivery systems using US and contrast agents. The underlying mechanisms are still unknown. One hypothesis is that oscillating microbubbles cause cell(More)