Thin-film-based field penetration engineering for surface plasmon resonance biosensing

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Evanescent-wave-based sensing, including surface plasmon resonance (SPR), relies on penetration depth to define its measurable range.
• Controlling this penetration depth is crucial for optimizing SPR sensor performance and expanding their applications.

Purpose of the Study:

• To investigate methods for varying the penetration depth in SPR sensing structures.
• To explore the use of dielectric layers for controlling penetration depth.
• To compare field penetration in dielectric multilayers with localized SPR structures.

Main Methods:

• Implementation of dielectric layers within an SPR sensing structure.
• Application of effective medium theory to model field penetration in dielectric multilayer designs.
• Comparative analysis of field penetration between dielectric multilayers and periodic nanowire-based localized SPR structures.

Main Results:

• Demonstrated that penetration depth in SPR structures can be controllably increased or decreased by adjusting dielectric layer configurations.
• Effective medium theory accurately describes field penetration in multilayer dielectric designs.
• Variations in penetration depth were observed in response to environmental changes.

Conclusions:

• Dielectric layers offer a versatile approach to tune the penetration depth in SPR sensors.
• The findings provide a foundation for designing SPR sensors with tailored sensing depths for specific applications.
• Understanding and controlling penetration depth is key to advancing evanescent-wave sensing technologies.