Imaging for biology and health (IBS)

Full field optical imaging of a mouse retinal explant

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Emmanuel FORT

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Ignacio IZEDDIN

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Michael ATLAN

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Pedro BARAÇAL DE MECÊ

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Claude BOCCARA

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Maïmouna BOCOUM

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Clément CABRIEL

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Bruce DENBY

Emmanuel FORT

Tel.: +33 (0)1 80 96 30 35

Ros-Kiri ING

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Ignacio IZEDDIN

Tel.: +33 (0)1 80 96 30 75

François RAMAZ

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Olivier THOUVENIN

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Sensitivity of Lamb waves in viscoelastic polymer plates to surface contamination Spytek, J., D. A. Kiefer, R. K. Ing, C. Prada, J. Grando, and J. De Rosny Ultrasonics 149, 107571 (2025) Abstract: Detecting surface contamination on thin thermoformed polymer plates is a critical issue for various industrial applications. Lamb waves offer a promising solution, though their effectiveness is challenged by the strong attenuation and anisotropy of the polymer plates. This issue is addressed in the context of a calcium carbonate (CaCO3) layer deposited on a polypropylene (PP) plate. First, the viscoelastic properties of the PP material are determined using a genetic algorithm inversion of data measured with a scanning laser vibrometer. Second, using a bi-layer plate model, the elastic properties and thickness of the CaCO3 layer are estimated. Based on the model, the sensitivity analysis is performed, demonstrating considerable effectiveness of the A1 Lamb mode in detecting thin layers of CaCO3 compared to Lamb modes A0 and S0. Finally, a direct application of this work is illustrated through in-situ monitoring of CaCO3 contaminants using a straightforward inter-transducer measurement.
Submacular Choroidal Arteries: A Laser Doppler Holography and OCT Study Paques, M., Z. Bratasz, L. Puyo, C. Chaumette, D. Castro Farias, M. Atlan, and S. Mrejen Ophthalmology Science 5, no. 3, 100709 (2025) Abstract: Objective: To document the aspect, topography and morphometry of normal human choroidal arteries in the posterior pole by laser Doppler holography (LDH) and OCT. Design: Cross-sectional study. Subjects: Fifty-four eyes of 27 healthy subjects. Methods: A prototypic LDH system captured the laser Doppler shift of the choroidal circulation within the central 20°. Doppler shifts were filtered to extract high velocity vessels. Images of choroidal arteries identified by LDH were subsequently registered with en face and cross-sectional OCT images. Subsequently, the diameters of macular choroidal arteries and their correlation to central choroidal thickness was measured on OCT B-scans. Main Outcome Measures: Spatial disposition, distribution, and diameters of choroidal arteries. Results: Choroidal arteries were identified by LDH and OCT from their emergence from short posterior ciliary arteries (sPCAs), and could be traced to second and third divisions. In the 8 eyes that underwent LDH, 7 of 8 (88%) showed a horizontal first-order artery within 0.5 disc diameter from the fovea. OCT B-scans showed that first-order arteries were located along the sclera-choroid interface; around arteries, the choroidal tissue formed a pyramid-shaped avascular structure with a posterior base contiguous and isoreflective to the sclera. In a cohort of 49 eyes, the diameter of horizontal submacular arteries (average [± standard deviation] 136.3 μm [±47]; range, 70–209 μm) was weakly correlated to central choroidal thickness (P = 0.09). Conclusions: First-order choroidal arteries emerging from sPCAs are located along the sclerochoroidal interface and are surrounded by a pyramid-shaped avascular space, which contributes to differentiate them from veins. The majority of normal eye show a submacular first-order artery running horizontally toward the temporal periphery. These results will pave the way for a better knowledge of diseases affecting the choroidal circulation. Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
Rolling-phase dynamic full-field OCT Monfort, T., K. Grieve, and O. Thouvenin Optics Letters 50, no. 7, 2239-2242 (2025) Abstract: Dynamic full-field optical coherence tomography (DFFOCT) has recently emerged as an invaluable label-free microscopy technique, owing to its sensitivity to cell activity, as well as speed and sectioning ability. However, the quality of DFFOCT images is often degraded due to phase noise and fringe artifacts. In this work, we present a new implementation, to the best of our knowledge, named rolling-phase (RP) DFFOCT, in which the reference arm is slowly scanned over magnitudes exceeding 2π. We demonstrate mathematically and experimentally that it shows superior image quality while enabling to extract both static and dynamic contrast simultaneously. We showcase RP-DFFOCT on a macaque retinal explant and demonstrate its ability to better resolve subcellular structures, including intranuclear activity.
3D Single-Molecule Super-Resolution Imaging of Microfabricated Multiscale Fractal Substrates for Calibration and Cell Imaging Cabriel, C., R. M. Córdova-Castro, E. Berenschot, A. Dávila-Lezama, K. Pondman, S. Le Gac, N. Tas, A. Susarrey-Arce, and I. Izeddin ACS Applied Materials and Interfaces 17, no. 6, 9019-9034 (2025) Abstract: Microstructures arrayed over a substrate have shown increasing interest due to their ability to provide advanced 3D cellular models, which open up new possibilities for cell culture, proliferation, and differentiation. Still, the mechanisms by which physical cues impact the cell phenotype are not fully understood, hence the necessity to interrogate cell behavior at the highest resolution. However, cell 3D high-resolution optical imaging on such microstructured substrates remains challenging due to their complexity as well as axial calibration issues. In this work, we address this issue by leveraging the geometrical characteristics of fractal-like structures, which serve as axial calibration tools and modulate cell growth. To this end, we use multiscale 3D SiO2 substrates consisting of spatially arrayed octahedral features of a few micrometers to hundreds of nanometers. Through optimizations of both the structures and optical imaging conditions, we demonstrate the potential of these 3D multiscale structures as an alternative to electron microscopy for material imaging but also as calibration tools for 3D super-resolution microscopy. We used their multiscale and known geometry to perform lateral and axial calibrations in 3D single-molecule localization microscopy (SMLM) and assess imaging resolutions. We then utilized these substrates as a platform for high-resolution bioimaging. As a proof of concept, we cultivate human mesenchymal stem cells on these substrates, revealing very different growth patterns compared to flat glass. Specifically, the spatial distribution of cytoskeleton proteins is vastly modified, as we demonstrate with a 3D SMLM assessment. Keywords: 3D single-molecule localization microscopy; bioimaging; multiscale material; fractal-like microstructures; calibration; material imaging

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Presentation of the thematics

The IBS theme studies biological processes and tissues from the nanoscopic to the macroscopic scale. By studying in depth the interaction between different waves and biological matter, new non conventional imaging techniques are being developed. Super-resolution imaging is used to probe the organisation of matter at the single molecule scale and to understand the transport of these molecules in the cell environment, in particular in the nucleus. The full-field optical imaging team is interested in the organisation of biological tissues using label-free interferometric microscopy techniques to study the viability of organism’s cells and tissues for applications in both fundamental biology and in vivo medical diagnostics. The Holographic Doppler Imaging team develops new techniques to quantify blood flow in the retina of human patients. However, the optical approaches presented above are limited to shallow penetration depths in the human body (except from the transparent eye). In order to probe biological tissues at greater depths, it is becoming necessary to use other types of waves, in particular acoustic waves. Acousto-optic imaging enables tissue to be imaged with optical contrast at a depth of several millimetres by tagging the photons that are multiply scattered using acoustic waves. Finally, the use of acoustic waves enables the surface motion team to map vibratory deformations of the thorax in a non-contact, non-invasive manner.

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Imaging for biology and health (IBS)

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