Relative humidity sensor based on a silver nano-grating made from DVD discs

Area of Science:

• Nanotechnology
• Optical Sensing
• Materials Science

Background:

• Relative humidity (RH) monitoring is crucial for various applications, including environmental control and industrial processes.
• Developing sensitive and cost-effective RH sensors remains an active area of research.
• Existing sensors may face limitations in sensitivity, stability, or manufacturing cost.

Purpose of the Study:

• To propose and demonstrate a novel relative humidity sensor.
• To utilize silver nano-gratings fabricated from recycled optical discs as the sensing platform.
• To achieve high sensitivity and accuracy in RH detection.

Main Methods:

• Fabrication of silver nano-gratings using polycarbonate templates from discarded CD/DVD discs.
• Characterization of nano-gratings using optical measurements to determine refractive index sensing sensitivity.
• Finite-difference time-domain (FDTD) simulations to understand plasmonic properties.
• Coating the nano-grating with a humidity-sensitive porous silica layer for RH detection.

Main Results:

• Silver nano-gratings with different grating periods were successfully fabricated.
• The nano-gratings exhibited high refractive index sensing sensitivities (517 nm/RIU and 742.9 nm/RIU).
• FDTD simulations confirmed the excitation of surface plasmon polariton and localized surface plasmon modes.
• The optimized sensor demonstrated a relative humidity detection sensitivity of 0.23 nm/%RH.

Conclusions:

• A cost-effective and highly sensitive relative humidity sensor based on silver nano-gratings has been successfully developed.
• The use of recycled optical discs as templates offers a sustainable approach to nano-grating fabrication.
• The sensor shows significant potential for applications requiring precise environmental humidity monitoring.