Multipurpose Microreactor for X-ray-Based Coherent Imaging and Spectroscopy

Microfluidic devices have become important tools for conducting in situ and in vivo experiments using synchrotron radiation, proving effective across a wide energy range. However, with the advent of fourth-generation synchrotron sources, factors such as device thickness and electronic density uniformity have become critical for advanced techniques such as coherent imaging. In this work, we present the microfabrication process of a two-part, polymer-based microfluidic reactor and demonstrate how a multimodal approach combining X-ray absorption spectroscopy and ptychography enables the in situ investigation of a biomineralization process. The device was filled with a culture medium containing Acidithiobacillus ferrooxidans, a microorganism capable of oxidizing iron to form minerals such as jarosite and schwertmannite. The resulting crystals formed within the reactor were imaged using ptychography, achieving a spatial resolution of approximately 60 nm. Our results not only confirm the functionality of the fabricated microreactor but also represent a significant advancement in the capability to study processes at submicrometer scales, with implications for inorganic synthesis, bioassisted recycling, biomining, and a wide range of biotechnological applications.