Towards real-time on-catheter biofluid analysis with lens-free imaging

Lens-free imaging (LFI) is a fast, compact and cost-effective computational imaging technique that is capable of volumetric imaging of sparse samples. Though LFI systems can achieve high lateral resolution (~1 µm) over a large field-of-view, they conventionally assume weak scattering and lack depth resolution. Optical diffraction tomography (ODT), on the other hand, can provide 3D refractive index information with greater axial resolution under relaxed scattering assumptions. However, traditional ODT systems image relatively small sample volumes (<0.05 mm3) using elaborate lens-based configurations. Combining the benefits of these two approaches, we developed a compact lens-free optical diffraction tomography (LF-ODT) technology for high resolution 3D imaging of sparse biological samples including red blood cells, white blood cells and bacteria in a thick volumetric sample (~0.5 - 1 mm3). This research demonstrates the promise of a catheter-inline LFI-ODT technology for continuous real-time monitoring of biological fluids in healthcare settings.