**3.1 Incorporating microfluidic experiments into SAXS**

After the microfluidic devices are designed, fabricated, tested and fluid control is established, final considerations involve the implementation of the complete setup in an X-ray beam, either in a SAXS lab instrument or at a synchrotron beamline. Depending on SAXS instrument design a number of adjustments and considerations are required to achieve good integration for the measurement. As every synchrotron has slightly different parameters and sample environments, it is recommended to contact the beamline staff if considering a microfluidic-based time-resolved SAXS experiment for specific advice.

## *3.1.1 Device modifications*

SAXS measurements are dependent on the volume and composition of all objects in the X-ray beam. Consideration should therefore be given to not only the material's resistance to radiation damage, but also the relative volumes of device material and sample that are going to be presented over the measurement channel. For example, 2–3 mm of any device-polymer either side of a sample channel of 50
