Microfluidic Gratings for X-Ray Phase Contrast Imaging

Fabrication of X-ray gratings has surged in the last two decades thanks to their key role in X-ray Phase Contrast Imaging, an imaging technique able to boost X-ray sensitivity to detect otherwise invisible details. These high aspect ratio devices are usually fabricated by complex, costly, multi-step processes that limit their size and production throughput. These steps commonly involve UV or X-ray lithography, semiconductor selective etching, and high-Z metal plating, usually Au, which require expensive tools and materials. Here we present a proof-of-concept fabrication via soft lithography and Hg infusion of microfluidic X-ray absorption gratings and their performance in biomedical imaging. In this work, we demonstrate gratings with a thickness of 21 $\mu m$ , made of 10 $\mu m$ -wide lamellae and 59 $\mu m$ -wide Hg-filled channels. While these initial parameters were chosen to validate the infusion process, significantly higher aspect ratios are attainable using similar, established microfluidic fabrication techniques. Such fabrication technique requires fewer, less expensive, and more scalable processes using alternative and more sustainable materials, while showing comparable visibility with their conventional Au-based, solid equivalent. Our results constitute a promising shift in X-ray optics fabrication that could significantly lower barriers to commercialization and accelerate the practical deployment of X-ray Phase Contrast Imaging.