In the realm of imaging technologies, one enduring challenge has been the visualization of objects obscured by dense, scattering environments—settings so opaque that traditional optical or acoustic techniques fail to reveal anything beyond an impenetrable haze. Whether peering through thick clouds, murky waters, or biological tissues, the scattering phenomena significantly convolute the incoming signals, rendering the hidden objects effectively invisible. A groundbreaking interdisciplinary collaboration between researchers at the Institut Langevin in France and TU Wien in Austria has now unveiled a novel mathematical approach that remarkably circumvents these limitations, enabling the precise detection and localization of concealed targets. Their innovative framework, centered on what they term the ‘fingerprint matrix’, heralds a new paradigm in imaging within complex media.
At the heart of this advancement lies a deep appreciation of wave physics as it pertains to imaging. Whether relying on visible light, ultrasound waves, or other probing signals, imaging fundamentally depends on the emission of waves that interact with an object and subsequently scatter back toward detectors. This reflected wave carries encoded information about the object’s position and structure. However, an environment rife with multiple scattering—where waves bounce innumerable times off heterogeneous media before reaching the detector—complicates this interaction. Instead of a straightforward reflection, what arrives at the receiver is a tangled superposition of waves, obscuring the object’s presence. As Professor Stefan Rotter from TU Wien articulates, such an environment effectively turns the wave signal into a diffuse fog, erasing clarity and frustrating attempts at reliable detection.
This phenomenon of multiple scattering undermines a broad array of imaging modalities, from sonar navigation in submarine operations to medical ultrasound diagnostics. When waves traverse complex media like sand or biological tissues, their paths become unpredictable, and interpretations based on conventional imaging assumptions falter. Current methodologies either accept poor resolution or necessitate invasive procedures to circumvent scattering effects. The newly presented approach eschews these compromises, offering a non-invasive, mathematically rigorous alternative.
The conceptual breakthrough stems from leveraging the unique, intrinsic scattering signature of an object when placed in a scattering-free or minimally scattering environment. By examining a target’s wave scattering response under controlled conditions, the researchers generated what they describe as a ‘scattering matrix’—a comprehensive mathematical encapsulation of how the object modulates incident waves. This matrix acts as a distinctive fingerprint that represents the object’s interaction with waves in an idealized context devoid of environmental complexity.
When the same object resides within a strongly scattering medium, such as metal spheres buried in sand, direct imaging is infeasible. Nonetheless, the waves that penetrate these media and interact with the object retain subtle imprints of the object’s presence, albeit buried within a cacophony of scattered signals. The research team’s method melds the previously acquired ‘fingerprint matrix’ with new measurements of wave reflections from the complex environment. Employing advanced correlation techniques, they extract the buried object’s location by discerning consistencies between the noisy reflected waveforms and the pristine scattering matrix.
This detection strategy exemplifies a profound synergy between experimental physics and applied mathematics. It transforms the labyrinthine problem of multiple scattering into a solvable inverse problem by mathematically teasing out the embedded object’s signature. According to Professor Rotter, this correlation-driven inference permits pinpointing the object even when it is thoroughly hidden beneath layers of scattering media, overcoming a challenge that has long eluded traditional imaging methods.
Experimental validation of the technique was conducted with steel balls concealed under sand layers, demonstrating robust and accurate localization that transcended the noise of multiple scattering. Beyond experimental physics, the potential for clinical translation is particularly compelling. The research highlights diagnostic applications in oncology, notably in the monitoring of breast cancer progression. In this context, small lesion markers implanted within tissues are notoriously difficult to visualize clearly due to overwhelming background scattering. Application of the fingerprint matrix methodology conclusively enhanced the detectability of these markers, promising improved patient monitoring and potentially earlier intervention.
In addition to oncological imaging, the approach proved valuable in assessing muscle fibers, a critical factor in diagnosing and understanding neuromuscular and cardiac diseases. Imaging muscles with high fidelity is complicated by biological tissue heterogeneity and scattering; thus, non-invasive techniques that provide clearer insights into muscle architecture can revolutionize clinical care. The fingerprint matrix framework opens new avenues for such applications, potentially enhancing diagnostic precision and enabling earlier detection of pathological changes.
The inherent versatility of the fingerprint matrix extends beyond ultrasound-based methods. Theoretically, any wave-based detection system that allows for accurate measurement of reflection or scattering matrices could benefit from this approach. Optical systems, in particular, stand to gain considerable advantages. The technology could thus impact a swath of scientific disciplines—ranging from oceanography to astrophysics—where deciphering signals hidden within complex scattering environments is paramount.
Furthermore, some targets’ scattering fingerprints dynamically shift in response to variations in physical parameters such as pressure or temperature. The ability to remotely monitor these changes represents an exciting offshoot of the novel method, providing a non-contact means of sensing environmental or physiological conditions with unprecedented sensitivity. For instance, in neuroimaging, where wave propagation through the human skull—characterized by strong scattering—poses significant barriers, the fingerprint matrix offers a tantalizing route toward improved measurement of brain activity and disorders.
This promising technique is not confined to academic inquiry but has also attracted commercial and translational interest. Collaborations with CNRS Innovation and TU Wien’s Patent & Licence Management Department ensure the method’s intellectual property protection, facilitating pathways to medical technology development. A medical technology company has already shown interest in further advancing fingerprint matrix applications, signaling a potential leap from laboratory success to real-world impact.
The publication detailing this pivotal breakthrough appears in Nature Physics, marking a significant milestone in physical sciences and technological innovation. Published on October 2, 2025, the article outlines the experimental and theoretical foundations of the fingerprint matrix and articulates its broad applicative horizon. This research not only challenges preconceived limitations of imaging in complex media but also posits a transformative framework for future explorations at the intersection of physics, mathematics, and biomedicine.
By harnessing the unique interaction patterns between waves and objects, stripped from the convoluting noise of multiple scattering, the fingerprint matrix technique redefines what is possible in imaging science. It not only unlocks hidden worlds buried within dense media but also lays the groundwork for enhanced diagnostic tools, environmental sensing, and fundamental science investigations. As such, it represents a beacon of innovation, with the potential to revolutionize multiple domains that rely on wave-based imaging and sensing.
Subject of Research: Not applicable
Article Title: Detection and characterization of targets in complex media using fingerprint matrices
News Publication Date: 2-Oct-2025
Web References: http://dx.doi.org/10.1038/s41567-025-03016-2
References: Article published in Nature Physics
Image Credits: TU Wien / Arthur Le Ber
Keywords
Fingerprint Matrix, Multiple Scattering, Wave Physics, Ultrasound Imaging, Complex Media, Inverse Problem, Signal Processing, Medical Diagnostics, Breast Cancer Monitoring, Muscle Fiber Imaging, Non-invasive Detection, Reflection Matrix, Scattering Matrix
