Common framework for surface plasmon binding and voltage sensing and microscopy with transmission line...

Area of Science:

• Optoelectronics
• Nanotechnology
• Biophysics

Background:

• Surface plasmon resonance (SPR) is crucial for detecting biomolecular binding events.
• Emerging applications of SPR include voltage and electrical impedance measurements.
• The physical mechanisms for binding and voltage sensing appear distinct.

Purpose of the Study:

• To develop a unified framework for surface plasmon sensing.
• To represent binding and voltage sensing using a common transmission line and impedance model.
• To analyze the contribution of amplitude and phase to sensing performance.

Main Methods:

• Development of a transmission line and impedance model for surface plasmon sensing.
• Graphical representation of the gold layer's effect on reflectivity.
• Analysis of amplitude and phase changes in the detected signal.

Main Results:

• The unified model demonstrates that binding and voltage sensing share common principles.
• Optimum sensitivity is achieved with a gold layer thickness of approximately 48 nm.
• Phase detection offers superior sensitivity over intensity measurement.
• Measuring complex amplitude (amplitude and phase) provides even greater sensitivity.

Conclusions:

• A unified transmission line model effectively describes surface plasmon sensing for binding and voltage detection.
• The model elucidates the critical role of gold layer thickness and signal amplitude/phase.
• Complex amplitude measurement represents a promising avenue for enhancing detection sensitivity in SPR.