Ondes, complexité et information (OCI)

Forêt de tiges : un modèle de diffusion multiple utrasonore

Responsable

Alexandre AUBRY

Tél. : 01 80 96 30 66

Co-responsable

Sébastien POPOFF

Tél. : 01 80 96 39 48

Membres permanents

Alexandre AUBRY

Tél. : 01 80 96 30 66

Julien DE ROSNY

Tél. : 01 80 96 30 52

Arnaud DERODE

Tél. : 01 80 96 30 67

Mathias FINK

Tél. : 01 80 96 30 69

Emmanuel FORT

Tél. : 01 80 96 30 35

Abdelwaheb OURIR

Tél. : 01 80 96 30 39

Sébastien POPOFF

Tél. : 01 80 96 39 48

Actualités

Non-linear coupling in two non-linear delayed acoustic resonators Reda, J., M. Fink, and F. Lemoult Journal of the Acoustical Society of America 158, no. 3, 2130-2137 (2025) Résumé: Building on our previous work on a Hopf resonator that mimics the cochlear amplifier from Reda, Fink, and Lemoult [(2023). Europhys. Lett. 144(3), 37001], we now turn to the fact that the inner ear comprises thousands of such resonators, which interact through coupling mechanisms. To gain insight into these interactions, we investigate the coupling of two acoustic resonators with slightly detuned resonance frequencies, interacting through time-delayed feedback loops. By modulating the gain of the loop and the coupling strength, we demonstrate the emergence of frequency synchronization at low amplitudes and bifurcations leading to desynchronization at higher amplitudes. This tunable non-linear interaction offers insights into resonance phenomena in coupled systems, with potential implications for auditory modeling and complex acoustic systems.
Ultrasound matrix imaging for 3D transcranial in vivo localization microscopy Bureau, F., L. Denis, A. Coudert, M. Fink, O. Couture, and A. Aubry Science Advances 11, no. 31 (2025) Résumé: Transcranial ultrasound imaging is usually limited by skull-induced attenuation and high-order aberrations. By using contrast agents such as microbubbles in combination with ultrafast imaging, not only can the signal-to-noise ratio be improved, but super-resolution images down to the micrometer scale of the brain vessels can also be obtained. However, ultrasound localization microscopy (ULM) remains affected by wavefront distortions that limit the microbubble detection rate and hamper their localization. In this work, we show how ultrasound matrix imaging, which relies on the prior recording of the reflection matrix, can provide a solution to these fundamental issues. As an experimental proof of concept, an in vivo reconstruction of deep brain microvessels is performed on three anesthetized sheep. The compensation of wave distortions is shown to markedly enhance the contrast and resolution of ULM. This experimental study thus opens up promising perspectives for a transcranial and nonionizing observation of human cerebral microvascular pathologies, such as stroke.
Quantitative polarimetric wavefront imaging Blochet, B., G. Lelu, M. A. Alonso, and M. Guillon Optica 12, no. 7, 907 (2025)
Non-contact assessment of Cardiac Velocity profiles using Ultrasound based Surface Motion Camera: A feasibility study Sadhukhan, D., E. Saloux, C. Dorme, M. Fink, R. K. Ing, and A. Hodzic IEEE Journal of Biomedical and Health Informatics, 1-10 (2025) Résumé: Tissue Doppler imaging (TDI) mode of echocardiography plays a crucial role in diagnosing several cardiac conditions by recording the myocardial contraction velocities. To mitigate the need of experts for performing echocardiography, several studies have proposed the use of Seismocardiogram as an easier alternative to measure the cardiac timings. However, exact correlation with tissue Doppler measured cardiac velocities has not been explored. Moreover, most of the applications only use single channel contact accelerometers on the chest, thus limiting their utility. In this work, we propose the use of a novel airborne ultrasound based surface motion camera (SMC) for non-contact multichannel recording of cardiac induced surface velocities from the chest. Validation study was conducted on 30 healthy subjects with simultaneous recordings of single channel ECG along with the chest surface velocities followed by clinical Echocardiography. The SMC recorded surface velocity waveforms show correlation similarity of over 0.6 with Tissue Doppler velocity waves extracted from the echocardiographic images. Discrete time warping based distance analysis was also performed to quantify their morphological similarity. Quantitative parameters including the peak systolic velocity and amplitude ratio extracted from the chest recordings show a linear correlation (R<sup>2</sup> greater than 0.8) with that of the TDI values. Additionally, multichannel recording allows visualization of the velocity profiles on the chest and efficiently captures the spatial variations for left ventricular and septal sites. Hence, this new modality shows the potential to be a vital diagnostic technique for non-contact and robust monitoring of the cardio-mechanical functions.

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Présentation du thème

Les avancées technologiques et scientifiques des quinze dernières années, auxquelles l’Institut Langevin a contribué de manière pionnière, ont considérablement élargi notre capacité à contrôler les champs optiques, électromagnétiques et acoustiques avec une précision spatio-temporelle sans précédent. Grâce à ces progrès, il est désormais possible d’explorer et d’exploiter un nombre impressionnant de degrés de liberté, ouvrant ainsi des perspectives innovantes pour de nombreuses applications.

D’une part, les télécommunications bénéficient particulièrement de ces avancées, permettant des transmissions plus rapides, plus fiables et plus sécurisées. D’autre part, l’imagerie en milieux complexes profite largement de ces progrès grâce à une approche matricielle exhaustive, exploitant toute l’information disponible pour améliorer significativement la qualité et la précision des images obtenues.

En parallèle à ces travaux appliqués, des études plus fondamentales sont menées, notamment sur les ondes de gravité, qui sont particulièrement adaptées pour l’exploration des milieux dépendant du temps. Ces recherches fondamentales sont essentielles pour approfondir notre compréhension des phénomènes complexes et ouvrir de nouvelles voies de recherche.

Ainsi, la manipulation de l’information dans des milieux complexes devient plus sophistiquée et efficace, facilitant des développements dans divers secteurs tels que la médecine, les sciences de la terre, l’ingénierie, et bien d’autres.

En somme, les contributions de l’Institut Langevin jouent un rôle crucial dans la transformation de ces découvertes scientifiques en solutions pratiques et innovantes, redéfinissant ainsi les frontières de ce qui est possible.

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