TRA Based Ultrasound Focusing

Time Reversal Acoustics (TRA) is a novel concept introduced by Mathias Fink of the University of Paris for focusing and steering acoustic beams in complex heterogeneous media. Scattering, refractions and reflections in highly inhomogeneous media, which distort focusing in conventional acoustic focusing systems and are viewed as a significant technical hurdle, lead to improvement of the focusing ability of the TRA system. Thus, TRA takes advantage of these usually undesirable processes. Artann Laboratories has developed a family of TRA Electronic Systems for a variety of medical and industrial applications based on Time Reversal Acoustics principles. The systems can receive, digitize, store, time reverse and transmit acoustic signals in a wide frequency range from 0.01 to 10 MHz. TRA systems can focus and stir an ultrasound beam using just a few piezoceramic transducers glued to the facets of an aluminum block. Advantages of TRA system include its ability to produce pulses with arbitrary waveforms in a wide frequency range.

Biomedical applications of TRA

TRA systems developed in Artann were used in numerous biomedical applications, such as Shear Wave Elasticity Imaging, ultrasound assisted drug delivery, nonlinear imaging and treatment of atrial fibrillation.
The NIH funded projects of Artann based on the use of the TRA principles include “Diagnostic Technologies Based on Acoustic Radiation Force”, ”MR Elastography Using Time Reversed Acoustics”, conducted in collaboration with the University of Michigan, Ann Arbor, and an ongoing project “Time-reversal acoustic device for enhanced drug delivery for brain gliomas” conducted in collaboration with Cornell University.

TRA in nondestructive testing

Structural Health Monitoring

In a project “Time Reversal Acoustic Structural Health Monitoring Using Array Of Embedded Sensors" funded by NASA and conducted in collaboration with Los Alamos National Laboratories, Artann developed a new approach to in-situ nondestructive evaluation (NDE) for airspace, automotive, and other industries based on TRA principles. TRA-based focusing of ultrasonic waves in combinations with embedded sensors and nonlinear acoustic methods has a potential of highly improving sensitivity of conventional acoustic NDE methods. The TRA focusing system provides high concentration of the ultrasound energy in the tested region, thus enhancing nonlinear acoustic effects (for example, higher harmonic generation). The analysis of TRA signal distortion and nonlinear acoustic effects in the different paths of propagation provides information necessary for tomographic mapping of damage and degradation.

Nondestructive Evaluation of Composite Materials

In a project funded by the DOD/Air Force “Vibration Based Structural Health Monitoring using Time Reversal Acoustics”, Artann developed a prototype of a portable device based on the TRA principles for assessment of fiber composites and fiber hybrids, for quality control in the manufacturing, and the assessment of structural integrity of materials prior to assembly, immediately following assembly, and during operational life. Although immediate applications of the device are for detection of flaws, cracks, and progressive damage of composite material parts, the approaches and instrumentation developed in Artann is also applicable to a multitude parts, structures and samples featuring a variety of materials and shapes, including all composite materials, carbon and graphite fiber, metals, glass, sandstone, and concrete parts.

Nonlinear Time Reversal Acoustic Method of

Friction Stir Weld Assessment

The goal of project “Nonlinear TRA for Stir Wield Assessment” funded by NASA was to prove that nonlinear TRA methods can serve as a sensitive means for non-destructive evaluation in a particular application: detection of defects in the friction stir welds (FSW). The results of the study fully confirmed and exceeded our expectations for the effectiveness of the nonlinear TRA in FSW assessment. Various methods of nonlinear effects measurements: harmonics and combination frequency generation, phase inversion, and varied amplitude, were investigated and the simplest and fastest high harmonic generation method was chosen for FSW sample scans. The measurements demonstrated the significant increase of nonlinear effects in defective FSW in comparison with the good quality FSW. The developed Nonlinear TRA system provided mapping of the weld nonlinear parameter that allowed localization of defected area.

Land Mine Detection

Artann in collaboration with Los Alamos National Laboratory conducted a project “Land Mine Detection by Time Reversal Acousto-Seismic Method” supported by the Department of Defense. Artann developed a method of land mine detection based on the combination of TRA with nonlinear acoustic method. TRA is very effective at focusing seismic waves in time and space, significantly improving detection capabilities using both linear and nonlinear acoustic wave methods. The feasibility of the developed approach was proven in the laboratory test and in small scale field experiments.

Publications and Patents

1. Sinel’nikov ED, Sutin AM, Sarvazyan AP: Time reversal in ultrasound focusing transmitters and receivers. Acoustical Physics 2010; 56(2): 183–193.
2. Sinelnikov YD, Sutin AM, Vedernikov AY, Sarvazyan AP: Time reversal acoustic focusing with a catheter balloon. Ultrasound in Medicine and Biology 2010; 36(1): 86-94.
3. Sarvazyan AP, Fillinger L, Gavrilov LR: A comparative study of systems used for dynamic focusing of ultrasound. Acoustical Physics 2009; 55(4-5): 630–637.
4. Sutin A, Libbey B, Fillinger L, Sarvazyan A: Wideband nonlinear time reversal seismo-acoustic method for landmine detection. J Acoust Soc Am 2009; 125(4): 1906-10.
5. Fillinger L, Kurtenoks V, Lewis Jr G, Sutin A, Sarvazyan A: Time reversal ultrasound system for enhanced drug delivery in rat brain. Proc 9th International Symposium on Therapeutic Ultrasound, Aix en Provence, September 23-26, France, 2009; 105.
6. Fillinger L, Sutin A, Sarvazyan A: Time Reversal Acoustic focusing with random reverberator. J Acoust Soc Am 2008; 123: 3338.
7. Sinelnikov Y, Vedernikov A, Sutin A, Sarvazyan A: Time Reversal Acoustic focusing using layered membranes structure. J Acoust Soc Am 2008; 123: 3430.
8. Sarvazyan A: Ultrasonic transducers for imaging and therapy based on time-reversal principles. J Acoust Soc Am 2008; 123: 3429.
9. Fillinger L, Kurtenoks V, Rosenblum S, Sutin A, Sarvazyan A: Flexible tools for time reversal acoustics focusing applications. J Acoust Soc Am 2007; 122: 3009.
10. Fillinger L, Sutin A, Sarvazyan A: Time reversal focusing of short pulses. Proc 2007 IEEE Ultrasonics Symposium, NY, 2007; 220-223.
11. Fillinger L, Sutin A, Libbey B, Sarvazyan A: Varied amplitude nonlinear acoustic method of landmine detection. J Acoust Soc Am 2007; 122(5): 3060.
12. Sutin A, Libbey B, Sarvazyan A: Nonlinear time reversal acoustic method of land mine detection: experiment and modeling. J Acoust Soc Am 2007; 121(5): 3163.
13. Sinelnikov Y, Vedernikov A, Sutin A, Sarvazyan A: Time reversal acoustic focusing with liquid-filled reverberator. J Acoust Soc Am 2007; 121(5): 3083.
14. Sutin A, Kurtenoks V, Sabatier J, Burgett R, ONeil M, Aranchuk S, Libbey B, Sarvazyan A: Time-reversal acoustic focusing of waves produced by seismic vibrators. J Acoust Soc Am 2006; 120: 3369.
15. Libbey B, Fenneman D, Sutin A, Kurtenoks V, Sarvazyan A: Wide-bandwidth time-reversal techniques for landmine detection. J Acoust Soc Am 2006; 119: 3387.  
16. Sutin A, Libbey B, Sarvazyan A: Phase inversion and two-frequency interaction in nonlinear time-reversal acoustic method of land mine detection. J Acoust Soc Am 2006; 120: 3368.
17. Choi BK, Sutin A, Sarvazyan A: Comparison of time reversal acoustic and prefiltering methods of focusing of tone burst signals. J Acoust Soc Am 2006; 120: 3282.
18. Choi BK, Sutin A, Sarvazyan A: Time reversal acoustic focused field and its prediction based on impulse response. Proc 9th Western Pacific Acoustic Conference, Seoul, Korea, 2006.
19. Choi BK, Sutin A, Sarvazyan A: Formation of desired waveform and focus structure by time reversal acoustic focusing system. Proc 2006 IEEE Int Ultrasonics Symposium, Vancouver, Canada, 2006: 2177-2181.
20. Sutin A, Libbey B, Kurtenoks V, Fenneman D, Sarvazyan A: Nonlinear detection of land mines using wide bandwidth time-reversal techniques. Ed: Broach JT, Harmon RS, Holloway JH, Jr. Detection and Remediation Technologies for Mines and Minelike Targets XI. Proc SPIE 2006; 6217: 398-409.
21. Sinelnikov Y, Sutin A, Zou Y, Sarvazyan A: Time reversal acoustic focusing with liquid resonator for medical applications. Trans 6th Int Symposium on Therapeutic Ultrasound International Society for Therapeutic Ultrasound, Oxford, UK, August 30th - September 2nd, 2006; 82-86.
22. Dos Santos S, Choi BK, Sutin A, Sarvazyan A: Nonlinear Imaging Based on Time Reversal Acoustic Focusing. Congrès Français d’Acoustique, Tours, France, 2006; 359-362.