Transducer designs and simulations for high frequency scanning acoustic microscopy for applications in exploring contrast mechanism and the mechanical properties of biological cells

Abstract

Scanning acoustic microscopy (SAM) has been extensively accepted and utilized for acoustical cellular and tissue imaging including measurements of the mechanical and elastic properties of biological specimen. SAM provides superb advantages: it is a noninvasive method; it can measure mechanical properties of biological cells or tissues; and fixation/chemical staining is not necessary. The first objective of this research is to develop a program for simulating the images and contrast mechanism obtained by high-frequency SAM. Computer simulation algorithms based on Matlab® were built for simulating the images and contrast mechanism. The mechanical properties of HeLa and MCF-7 cells were computed from the V(z) measurement data. Algorithms for simulating V(z) responses involved calculation of the reflectance function and were created based on ray theory and wave theory. The second objective is to design transducer arrays for SAM. Theoretical simulations based on Field II programs of the high frequency ultrasound array designs were performed to enhance image resolution and volumetric imaging capabilities. The new transducer array design will be state-of-the-art in improving the performance of SAM by electronic scanning and potentially providing a four-dimensional image of the specimen. Phased array beam forming and dynamic apodization and focusing were employed in the simulations.