Biology subjects

Bay, B. K.

Publications and source records attributed to Bay, B. K..

3 recordsLinked to original sources

bioRxiv2026

Optimising digital volume correlation across materials: a practical framework for accuracy and spatial resolution

Digital volume correlation (DVC) provides full-field three-dimensional measurements of internal deformation, but its accuracy and effective spatial resolution depend on image-processing and analysis choices. Here, we use fibrous, cartilaginous and mineralised tissues within a rat intervertebral disc (IVD) as a controlled multi-material case study, combining virtual compression with experimentally loaded synchrotron computed tomography images. We systematically evaluate phase retrieval and image filtering, bit-depth conversion, point-cloud design, subvolume size and strain-field smoothing. Stronger phase retrieval reduced correlation residuals while increasing displacement and strain errors, showing that residual minimisation alone can select poorer parameters. Image filtering sensitivity was greatest in fibrous tissue, which had the smallest characteristic image feature size, whereas inappropriate intensity mapping during 16-bit to 8-bit conversion preferentially degraded low-contrast cartilage. Increasing subvolume size, point spacing or strain-window size improved measurement robustness but progressively smoothed local strain heterogeneity. We demonstrate that the spatial resolution of strain measurement must be matched across tissue types in order to compare strain magnitude; in the IVD, matching DVC spatial resolution changed the apparent ratio of compressive strain among fibrous, cartilaginous and mineralised tissues from 3.1:1.9:1 to 14:7.7:1. These findings establish a sequential, deformation-based optimisation framework in which image characteristics guide processing, known deformations validate accuracy and strain fields are compared at matched measurement scales. The framework supports more reproducible and mechanically interpretable DVC analyses in heterogeneous biological and engineered materials.

bioengineering↗

bioRxiv2025

Multimodal X-ray imaging reveals hierarchical fibre mechanics

Fibrous materials--ranging from connective tissues to engineered composites--are vital to many biological and man-made systems, optimised to withstand complex in-operando or in-vivo loading. The spines intervertebral discs (IVD) load-bearing capacity depends on a hierarchical extracellular matrix, where plywood-like lamellae of collagen fibres in the annulus fibrosus contain nanometre-scale fibrils built from staggered triple-helical monomers. How intact IVDs couple fibril-scale mechanics to fibre-scale organisation under load remains unresolved. Here we introduce TomoSAXS, a full-field 3D small-angle X-ray scattering tomography that maps fibril-to-fibre mechanics across an intact tissue. We show that intrafibrillar molecular pre-strain (D-period stagger) is lamellar textured and tightly correlated with microscale fibre strain. Pre-strain is inversely related to fibril strain and its variability, consistent with load-sharing through molecular unwinding. Radial strain bridges and high-curvature zones at the annulus fibrosus-nucleus pulposus interfaces emerge as critical regulators of local mechanics. These findings reveal concerted fibril-fibre interactions that sustain mechanical equilibrium in the IVD, preserving elasticity and shape. More broadly, TomoSAXS establishes a platform to visualise nano- to micro-scale matrix mechanics across biological and synthetic fibrous materials, with applications in ageing and disease, therapeutic evaluation, and the design of bio-based and bioinspired materials.

bioengineering↗

bioRxiv2024

Multimodal imaging reveals multiscale mechanical interplay in vertebral endplate microarchitecture during intervertebral disc loading

The function of all musculoskeletal joints depends on hierarchical structures spanning the molecular to whole joint scales. Investigating biomechanics across length scales requires correlative multiscale experimental methods. This study applies multimodal in situ synchrotron imaging techniques to spinal joints - focussing on the vertebral endplates - to explore relationships between structure and mechanical strain across spatial scales. Strain mapping using digital volume correlation combined with microarchitectural analysis reveals that high tensile and shear strains play a role in the cartilage to bone transition. Correlative imaging and diffraction show that bone contains narrower mineral nano-crystallites under greater compressive prestrain compared to calcified cartilage. We hypothesise that this multiscale structural adaptation supports the mechanical function of the intervertebral disc. Future applications of the techniques presented here have potential to help unravel biomechanical underpinnings of pathologies affecting mineralised tissue structure. The multiscale structure-function relationships uncovered here may inspire the design of biomaterials and orthopaedic implants.

bioengineering↗