Schematic representation of the detection of uranyl ion using a microfluidic SERS device. Reprinted (adapted) from X. He, X. Zhou, Y. Liu and X. Wang, Ultrasensitive, recyclable and portable microfluidic surface-enhanced Raman scattering (SERS) biosensor for uranyl ions detection, Sens. Actuators, B, 2020, 311, 127676, with permission from Elsevier.300