Estimation of Shell Material Properties

Abstract

In the the theory chapters, Chapter 2 and Chapter 3, it was postulated that a shell enclosing the bubble will alter its acoustic properties. The aim of this chapter is to investigate the effect of the shell for oscillations in the linear range. The measurement technique in Chapter 4.1 is applied to characterize a contrast agent consisting of polymer-shelled air bubbles. The theoretical models of Chapter 2 are compared with the experimental results, and are used to estimate values for the visco-elastic shell parameters, values that are not known a priori. It is further shown how the results can be used to calculate the stiffness of the whole microbubble, the bulk modulus. This links it to results reported in a previous, phenomenological study [56, 61]. A version of the methods described here have also been applied to characterize the ultrasound contrast agent Sonazoid from Nycomed [157].