Fibre optic surface plasmon resonance sensor system designed for smartphones

Area of Science:

• Photonics and Sensor Technology
• Biomedical Engineering
• Materials Science

Background:

• Surface Plasmon Resonance (SPR) is a label-free optical sensing technique.
• Miniaturization of SPR sensors is crucial for portable diagnostic applications.
• Smartphone integration offers a platform for low-cost, accessible sensing.

Purpose of the Study:

• To report the first fiber optic SPR sensor system designed for smartphone integration.
• To demonstrate a simple fabrication method for the SPR sensor.
• To showcase the sensor's capability as a refractive index sensor.

Main Methods:

• Fabrication of an SPR sensor using silver coating on a 400 µm optical fiber with 45° end-faces.
• Utilizing smartphone flashlight for SPR excitation and camera for interrogation.
• Testing the sensor's performance with varying glycerol concentrations to measure refractive index.

Main Results:

• A functional fiber optic SPR sensor system integrated with a smartphone was successfully developed.
• The system requires no external electrical components for operation.
• A sensitivity of 5.96 × 10⁻⁴ RIU/pixel was achieved for refractive index measurements between 1.33 and 1.36.

Conclusions:

• The developed smartphone-based SPR sensor is a low-cost, portable solution.
• It holds significant potential for point-of-care diagnostics and environmental monitoring.
• Future integration into smartphone covers could enable real-time parameter monitoring.