Physical Acoustics Lab
Gruppo di Lavoro
The Physical Acoustics Lab at SBAI Department undertakes long-term, leading-edge researches on both acoustic wave propagation in complex media, including nonlinear eﬀects, and interaction of acoustic waves with matter.
Research activities are primarily focussed on the following two subjects:
1. Acoustic waveguides
The question: “How much time it takes for a quantum particle to tunnel through a barrier? ”, is a basic problem in quantum mechanics, being today also of technological importance. Backward propagating Lamb waves (plate modes) are used to experimentally investigate the transit time of phonons through a potential barrier. In backward wave propagation, the direction of the energy ﬂux, or group velocity, is antiparallel to the phase velocity direction, or direction of motion of the phase fronts. Backward wave propagation has seen a growing interest in both acoustic and optics due to fact that it oﬀers new ways to manipulate acoustic and optical ﬁelds and leads to non-intuitive physical eﬀects such as anomalous (negative) reﬂection and refraction phenomena on which, for example, acoustic cloaking eﬀect relies.
2. Biomedical ultrasonics
Ultrasound attenuation caused by dispersed solutions of microbubbles and nanobubbles, is an important phys-ical parameter that is measured in the Lab to improve the backscatter properties of such systems that are increasingly used as ultrasound contrast agents (UCAs) in clinical applications. Furthermore, the elastic char-acteristics of lipid-coated microbubbles and nanobubbles are becoming even more important to be measured as these systems have been recently promoted for transport and delivery of various bioactive substances. High frequency shear acoustic waves biosensors in a Quartz Crystal Microbalance (QCM) measuring system are used for non-invasive, label-free and highly sensitive chemical and cell biology studies with a special focus on cell-substrate interactions. Measurements on the rheological properties of biological ﬂuids are also carried out.
Lab equipment includes:
- High-frequency broadband ultrasonic pulse-echo measuring system with fourier trasform spectroscopy analysis for nondestructive evaluation of biological samples;
- Two computer-controlled optical interferometers for contactless amplitude measurement and frequency analysis of mechanical vibrations in frequency range 10 Hz - 40 MHz (displacement resolutions down to 1 nm, lateral resolution 10 μm). Vibrational amplitude map are generated with a ﬁeld-of-view up to 5 cm2;
- Network analyzer for real-time impedance measurement of ultrasound piezoelectric transducers;
- Computer-controlled Quartz Crystal Microbalance (QCM);
- Temperature-controlled apparatus for the study of cavitation and single-bubble sonoluminescence.
Figure 1: The Physical Acoustics Lab at SBAI Department