Humidity- and Temperature- Stimuli-Responsive Tunable Metal-Hydrogel-Metal Reflective Filter

Our work demonstrates a tunable reflectance filter based on a metal-hydrogelmetal structure responsive to humidity and temperature. The filter employs a hydrogel as an insulating layer. Swelling/deswelling and the volume phase transition of the hydrogel allow continuous reversible humidity- and/or temperature-induced tuning of the optical resonance.