Volatile organic compound sensing using a surface-relief D-shaped fiber Bragg grating and a polydimethylsiloxane...

Area of Science:

• Optoelectronics
• Chemical Sensing
• Materials Science

Background:

• Volatile organic compounds (VOCs) pose environmental and health risks, necessitating sensitive detection methods.
• Fiber Bragg gratings (FBGs) offer a robust platform for sensing applications due to their wavelength-selective properties.
• Polydimethylsiloxane (PDMS) is a versatile polymer with favorable optical and chemical properties for sensor development.

Purpose of the Study:

• To develop and evaluate a surface-relief fiber Bragg grating (SR-FBG) coated with polydimethylsiloxane (PDMS) as a sensor for volatile organic compounds (VOCs).
• To investigate the correlation between analyte absorption, refractive index changes in PDMS, and the resulting Bragg wavelength shift.
• To demonstrate the sensor's capability for chemical differentiation between specific VOCs in the gaseous phase.

Main Methods:

• Fabrication of a surface-relief fiber Bragg grating.
• Coating the SR-FBG with a thin layer of polydimethylsiloxane (PDMS).
• Exposure of the coated sensor to gaseous analytes (dichloromethane and acetone) and monitoring of the Bragg wavelength shift using an optical spectrum analyzer.

Main Results:

• The PDMS-coated SR-FBG exhibited a measurable Bragg wavelength shift upon exposure to VOCs.
• The direction and magnitude of the wavelength shift were found to be dependent on the specific chemical analyte absorbed by the PDMS layer.
• Successful differentiation between dichloromethane and acetone was achieved based on their distinct spectral responses.

Conclusions:

• The PDMS-coated SR-FBG is a promising platform for sensitive and selective VOC detection.
• The sensor's ability to differentiate between chemicals highlights its potential for complex mixture analysis.
• This approach offers a cost-effective and label-free method for real-time chemical sensing.