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▲ [16a-P02-4] Highly Sensitive Fluorescent Biopolymer Microresonator for Humidity Sensing
Keywords:biopolymer, optical resonator, humidity sensing
Biopolymers are promising materials in terms of biodegradability and sustainability. However, in the field of optical sensors, most of the devices or their elements still heavily rely on either inorganic or organic synthesized compounds. Optical humidity sensors are one of the representative missing parts among them due to the difficulty in realizing high-sensitivity and tolerance against high-humidity environment at the same time. Herein, we select silk fibroin (SF) as a naturally abundant and eco-friendly material for successfully making a SF microsphere that work as an active optical resonator for precise moisture sensing at high humidity. The aqueous SF self-assembles into micro-spherical particles inside micelles. SF microspheres doped with ionic dyes, upon photoexcitation, emit fluorescence with Whispering-gallery mode (WGM) resonance. The resonance peaks are responsive to the surrounding humidity with a sensitivity as high as 0.21 nm per percent relative humidity up to 95 %RH.