Scalable and cost-effective fabrication of X-ray absorption gratings via thin-film spray coating

X-ray grating interferometry (XGI) is a multimodal imaging technique that simultaneously retrieves absorption, phase-contrast, and dark-field signals, providing complementary contrast mechanisms for a wide range of samples. In particular, the phase-contrast and dark-field channels offer enhanced sensitivity to soft tissues and to microstructures below the imaging system’s spatial resolution, making XGI highly promising for medical diagnostics and security screening. However, the widespread adoption of XGI in clinical and industrial settings remains limited by the high cost and fabrication complexity of high aspect ratio absorption gratings, especially when scaling to large fields of view. In this work, we present a cost-effective method for fabricating high-energy X-ray absorption gratings by alternately spray-coating metal oxide microparticle layers and organic polymer films. This layer-by-layer approach avoids expensive lithography and electroplating processes, offering straightforward scalability for large-area production. A key advantage of the resulting structure is its inherent mechanical flexibility, which allows the grating to be bent to match the divergent X-ray wavefront, thereby expanding the usable field of view. To validate the approach, we fabricated a large-area absorption grating with a sub- \(40\ \upmu \text {m}\) period and an active area of \(140\ \text {mm} \times 25\ \text {mm}\) . X-ray characterization confirmed good period consistency within a representative \(25 \text {mm} \times 24\ \text {mm}\) region of the large-area grating. Because the absorber height is set by the slicing thickness rather than by the electroplating or deep etching, the same composite stack can be cut to whatever absorber thickness an imaging system requires, with the \(1\ \text {mm}\) slice studied here serving only as a representative example. For this slice, an X-ray transmission energy scan combined with spectrum-weighted Beer–Lambert inversion yielded a gold-equivalent absorber height of about \(206\ \upmu \text {m}\) at \(120\ \text {kVp}\) , a typical operating voltage for clinical lung dark-field CT. Radiation aging tests up to \(600\ \text {kGy}\) showed no statistically significant degradation in mechanical strength, demonstrating the grating’s suitability for XGI applications.