Monitoring human limb motion with ultrasound

9/25 Department Seminar

Dr. James M. Sabatier

Principal Scientist, National Center for Physical Acoustics
University of Mississippi

Sep. 25, 2013 3pm Weir Hall 235

SOAIR is developing an Eldercare SONAR for advanced Doppler ultrasonic instrumentation and measurement of ambulation gait activities in older adults.  The SONAR is optimized to measure specific motions in adult walk.  These are walk speed, walk cycle time and walk stride length and statistical variation of these parameters over several walk cycles.  These optimizations will allow for fall risk analysis and assessment of older adults.   Walking people create unique acoustic Doppler signatures that can be applied for human motion analyses.  The individual body segments (foot, leg, arm, torso, etc.) have different acoustic cross sections and velocities that form these unique human Doppler signatures.  Continuous-wave ultrasound is used to measure the Doppler shifted signal reflected from the body segments as the person moves.  The reflected ultrasonic signal from the human body is frequency modulated (FM) by the motion of the human body segments.  The acoustic cross section of the body segment influences the amplitude of the received Doppler signal.  These human motion Doppler signatures have been extensively studied using ultrasonic sonar systems.  To measure the human motion Doppler signals, the ultrasonic sonar uses commercially available, low-cost ultrasonic ceramic transducers.  The sonar is assembled from two identical ultrasonic transducers; one transducer acts as a transmitter emitting an ultrasonic wave while the other acted as a receiver – sensing the echoes.


Dr. James Sabatier retired from the University of Mississippi in January 2011 to form the startup company SOAIR, LLC to develop patented ultrasonic technologies for the eldercare community. Prior to this, he joined the faculty of the University of Mississippi in September 1984.   He holds a Ph.D. degree in Physics from the University of Mississippi (1984).   He is a member of the Acoustical Society of America (ASA) and was elected a Fellow of the Acoustical Society of America in 1992.   Dr. Sabatier has served as Principal Investigator for several successful research projects for the U. S. Department of Defense, U. S. Department of Agriculture, and other sponsors.   These research projects include development of acoustic-to-seismic (A/S) coupling techniques for landmine detection, acoustic measurement of spatial and temporal physical properties of soils, the development of specialized loudspeakers and ultrasonic techniques for monitoring the motion of humans.   He has served Intergovernmental Personnel Act (IPA) assignments in physical acoustics with the U. S. Army Engineer Research and Development Center Waterways Experiment Station, the U. S. Army Communications-Electronics Command Night Vision and Electronic Sensors Directorate and the U. S. Army Research Laboratory.   His expertise includes research in the fields of physical acoustics, the interaction of sound with porous media, and outdoor sound propagation and Doppler ultrasound. He currently holds the retired annuitant positions of Principal Scientist in the National Center for Physical Acoustics and Professor Emeritus in the Department of Physics and Astronomy and is the Owner of SOAIR, LLC.