Differential phase contrast X-ray imaging (DPCI) has gained a lot of interest in the past years. It is based on X-ray grating interferometry and the image quality is strongly dependant on the grating quality. Periodic line and space structures with periods in the micron range are required for the source and absorption grating. In case of energies > 30 keV their height should be larger than 100 μm resulting in aspect ratios of more than 100. Deep X-ray lithography and gold electroforming (LIGA technology) is used to fabricate these challenging structures. After resist, design and process optimization gratings with 2.4 μm period have been electroformed up to 120 μm, Visibilities of up to 70% for 29 keV and up to 20% for 52 keV have been achieved for monochromatic synchrotron light. Structures with larger periods could be manufactured up to 200 μm; further increase of the height and the gratings quality is possible yielding to high performance gratings also for high energies.

The possibility to perform high-sensitivity X-ray phase-contrast imaging with laboratory grating-based phase-contrast computed tomography (gbPC-CT) setups is of great interest for a broad range of high-resolution biomedical applications. However, achieving high sensitivity with laboratory gbPC-CT setups still poses a challenge because several factors such as the reduced flux, the polychromaticity of the spectrum, and the limited coherence of the X-ray source reduce the performance of laboratory gbPC-CT in comparison to gbPC-CT at synchrotron facilities. In this work, we present our laboratory X-ray Talbot-Lau interferometry setup operating at 40 kVp and describe how we achieve the high sensitivity yet unrivalled by any other laboratory X-ray phase-contrast technique. We provide the angular sensitivity expressed via the minimum resolvable refraction angle both in theory and experiment, and compare our data with other differential phase-contrast setups. Furthermore, we show that the good stability of our high-sensitivity setup allows for tomographic scans, by which even the electron density can be retrieved quantitatively as has been demonstrated in several preclinical studies.

An aerosol jet printing (AJP) printing head built on top of precise motion systems can provide positioning deviation down to 3 μm, printing areas as large as 20 cm × 20 cm × 30 cm, and five-axis freedom of movement. Typical uses of AJP are 2D printing on complex or flexible substrates, primarily for applications in printed electronics. Nearly all commercially available AJP inks for 2D printing are designed and optimized to reach desired electronic properties. In this work, we explore AJP for the 3D printing of free-standing pillar arrays. We utilize aryl epoxy photopolymer as ink coupled with a cross-linking “on the fly” technique. Pillar structures 550 μm in height and with a diameter of 50 μm were 3D printed. Pillar structures were characterized via scanning electron microscopy, where the morphology, number of printed layers and side effects of the AJP technique were investigated. Satellite droplets and over-spray seem to be unavoidable for structures smaller than 70 μm. Nevertheless, reactive ion etching (RIE) as a post-processing step can mitigate AJP side effects. AJP-RIE together with photopolymer-based ink can be promising for the 3D printing of microstructures, offering fast and maskless manufacturing without wet chemistry development and heat treatment post-processing.

X-ray imaging using a Talbot-Lau interferometer, consisting of three binary gratings, is a well-established approach to acquire x-ray phase-contrast and dark-field images with a polychromatic source. However, challenges in the production of high aspect ratio gratings limit the construction of a compact setup for high x-ray energies. In this study we consider the use of phase gratings with triangular-shaped structures in an x-ray interferometer and show that such gratings can yield high visibilities for significantly shorter propagation distances than conventional gratings with binary structures. The findings are supported by simulation and experimental results for both cases of a monochromatic and a polychromatic source.

An array of compound refractive X-ray lenses (CRL) with 20 × 20 lenslets, a focal distance of 20cm and a visibility of 0.93 is presented. It can be used as a Shack-Hartmann sensor for hard X-rays (SHARX) for wavefront sensing and permits for true single-shot multi-contrast imaging the dynamics of materials with a spatial resolution in the micrometer range, sensitivity on nanosized structures and temporal resolution on the microsecond scale. The object’s absorption and its induced wavefront shift can be assessed simultaneously together with information from diffraction channels. In contrast to the established Hartmann sensors the SHARX has an increased flux efficiency through focusing of the beam rather than blocking parts of it. We investigated the spatiotemporal behavior of a cavitation bubble induced by laser pulses. Furthermore, we validated the SHARX by measuring refraction angles of a single diamond CRL, where we obtained an angular resolution better than 4 $\mathsf{\mu }$ rad.