The image displays a flexible surface plasmon resonance (SPR)-based waveguide sensor prepared by directly imprinting metal nanoparticles onto flexible plates, as presented by Dehui Wan, Hsuen-Li Chen *, Yu-Ting Lai, Chen-Chieh Yu, King-Fu Lin. on page 1742. The metal nanoparticles could scatter the evanescent wave and the guiding mode waves from the SPR-based waveguide simultaneously. The scattering signal underwent a distinguishable red-shift when the target molecules bound to the particles.