Woodruff School of Mechanical Engineering
Acoustics and Dynamics Seminar
-3 piezoelectric composite materials for ultrasonic imaging probes: theory, characterization and several application
Dr. Dominique Certon
University of Tours
Tuesday, September 5, 2017 at 11:00:00 AM
Love Building, Room 109
Dr. Levent Degertekin
The key component of instrumentation chain in ultrasonic imaging is the transducer that transforms pressure field into electrical signal and conversely. The ultrasonic transducer plays a central role in defining the key performance parameters during imaging such as spatial resolution, central frequency, sensitivity, and signal-tonoise ratio. Today, to convert electrical signal into ultrasonic wave, the reference technology used in ultrasonic probes is based on piezoelectric materials. In 1980s, an idea to combine piezoelectric materials with passive polymers was proposed, leading to a new set of materials, so-called composite piezoelectric materials. The most common piezocomposite are made using rods of 1-3 piezoelectric materials that are regularly distributed in a polymer matrix, often realized in plate shaped configuration. Due to their manufacturing process (dice and fill method), rods are often equally spaced in the two dimensions, leading to a material with periodic microstructures. This contributes to the appearance of spurious modes that can drastically affect the performances of the device. After a brief reminder of the dice and fill fabrication method and properties of 1-3 piezocomposite, the first part of the present talk will focus on their electromechanical characterizations by means of laser interferometry measurements. Acoustic waves propagating in the substrate will be investigated to explain the origin of these modes and how periodicity affects the acoustic crosstalk. Based on this knowledge, in a first application, a new 1-3 piezocomposite fabricated with a super-cell structure will be presented, to overcome the limitations caused by spurious modes. The second part of the presentation is dedicated to the development of a high frequency linear array (30 MHz) based on new 1-3 lead-free piezocomposite. The first real time images obtained will be presented and compared with the standard lead-based piezoelectric materials (PZT).
Dominique Certon received the M.Sc. degree in signal processing and electrical engineering in 1991 from the University of Orleans, France. In 1994, he received the Ph.D. degree from the University of Tours, France. Finally, he obtained his Ha-bilitation a diriger les recherches (HDR) in applied acoustics and materials engineering from the Francois Rabelais University of Tours in 2010. He is an associate professor in telecommunication systems at the University of Tours. His research interests are in ultrasound probes for medical imaging based on capacitive micromachined transducers and piezoelectric technology. He is author or coauthor of more than 50 communications and publications. He is a member of the French Society of Acoustics and IEEE. Franck Levassort was born near Paris, France. He graduated in Applied Physics in 1990 and received the DEA (MSc) in Physical Acoustics from University Paris 7 (Denis Diderot) in 1991. In 1996, he received the Ph.D degree in ultrasound from the University Francois-Rabelais of Tours, France. From 1997 to 2013, he was an assistant professor and since 2014 he is a full professor of Electrical Engineering at the University Francois-Rabelais (Institute of Technology, Blois, France). His current interests are in design, modeling and characterization of piezoelectric composite materials and structures, as well as transducers for imaging applications. Since 2016, he is deputy director of GREMAN, a laboratory of 100+ in the field of materials, microelectronics, acoustics and nanotechnology.
Refreshments will be served.