In situ structural analysis with a SAXS laboratory beamline on a microfluidic chip

Abstract

Recent advances have been made in coupling microfluidic chips with X-ray equipment, enabling structural analysis of samples directly in microfluidic devices. This important step mainly took place at powerful synchrotron facilities because of the need for a beam reduced in size to fit the microfluidic channel dimensions but still intense. In this work, we discuss how improvements of an X-ray laboratory beamline and an optimal design of a microfluidic device allow reliable structural information to be obtained without the need for a synchrotron. We evaluate the potential of these new developments by probing several well known dispersions. These include dense inorganic gold and silica nanoparticles that scatter photons quite intensely, the bovine serum albumin (BSA) macromolecule, with moderate contrast, to highlight possible applications in biology, and latex nanospheres with only weak contrast with the solvent to show the limits of the setup. We established a proof of concept for a versatile setup that will open the way for more complex lab-on-a-chip devices suitable for in situ and operando structural analysis by small angle X-ray scattering analysis without the necessity for a synchrotron source.