Open AccessNatural spider silk as a photonics component for humidity sensing
Author(s) -
Zhihai Liu,
Wei Liu,
Chuanzhen Hu,
Yu Zhang,
Xinghua Yang,
Jianzhong Zhang,
Jun Yang,
Libo Yuan
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.021946
Subject(s) - microfiber , materials science , silk , relative humidity , spider silk , spider , humidity , optics , refractive index , photonics , whispering gallery wave , supercontinuum , optical fiber , fiber , optoelectronics , composite material , photonic crystal fiber , physics , resonator , astronomy , thermodynamics
Biological microfibers are remarkable materials with diversity in their chemistry, structure and functions that provide a range of solutions for photonic structures. Here we proposed and demonstrated a humidity detection technique for spectral tuning of whispering gallery modes (WGMs) in a cylindrical microresonator formed by a piece of spider egg sac silk (SpEss) from Araneus Ventricosus. We launched a supercontinuum laser into the SpEss via a tapered single-mode fiber to excite WGMs. When the ambient humidity changed, the profile diameter and effective refractive index of the SpEss changed, which caused the WGM resonant dips to shift. The experimental results showed that when the relative humidity (RH) changed from 20% to 75% RH, the average testing sensitivity of the proposed sensor was 389.1 pm/%RH and the maximum testing sensitivity was 606.7 pm/%RH in the range of 60% to 75% RH. Also, the proposed SpEss-based humidity sensor showed a fast response time of 494 ms and good repeatability with fluctuations less than 8% compared with the initial test values. The SpEss-based sensor expanded the application of spider silk as a biodegradable and biocompatible material in biochemical sensing.