Biochemical Sensing Application of Surface Plasmon Resonance Sensor Based on Flexible PDMS Substrate

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Surface Plasmon Resonance (SPR) sensors offer label-free detection capabilities.
• Flexible SPR sensors are desirable for portable and wearable applications.
• Developing robust SPR chips on flexible substrates is crucial for advanced sensing.

Purpose of the Study:

• To design and implement a flexible SPR sensor chip using a gold film on a polydimethylsiloxane (PDMS) substrate.
• To evaluate the sensor's performance in terms of refractive index sensitivity, stability under mechanical stress, and accuracy in real-world sample analysis.
• To investigate the adsorption behavior of glutathione (GSH) on the gold surface under varying pH conditions.

Main Methods:

• Fabrication of an SPR chip via gold film deposition on a flexible PDMS substrate in a Kretschmann configuration.
• Characterization of refractive-index sensitivity using sodium chloride solutions at an optimized incident angle of 13°.
• Assessment of sensor stability through 50 bending cycles.
• Validation of sensor efficacy by detecting alcohol content in Chinese Baijiu samples and studying GSH adsorption kinetics at different pH levels.

Main Results:

• The SPR sensor achieved a high sensitivity of 3385.5 nm/RIU.
• The sensor demonstrated excellent mechanical stability, with only a 1% sensitivity variation after 50 bending cycles.
• Accurate detection of alcohol content in Baijiu samples was achieved, with a maximum relative error of 4.04%.
• Optimal immediate glutathione adsorption occurred at pH 12 due to mercapto group deprotonation, while the best film-forming effect was observed at pH 7.

Conclusions:

• The developed flexible SPR sensor exhibits high sensitivity, excellent mechanical robustness, and reliable performance for detecting analytes like alcohol.
• The sensor's ability to analyze molecular adsorption, as demonstrated with glutathione, highlights its potential for biochemical sensing applications.
• This flexible SPR chip design offers a promising platform for developing advanced, portable biosensing devices.