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Published on: November 23, 2015
Sensitive label-free biosensors by using gap plasmons in gold nanoslits
Kuang-Li Lee1, Way-Seen Wang, Pei-Kuen Wei
1Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
Biosensors & Bioelectronics
|May 24, 2008
Summary
Gap plasmons in gold nanoslit arrays exhibit higher sensitivity than surface plasmons for biomolecule detection. This enhanced sensitivity, particularly for narrow slits, stems from greater overlap with the target molecules.
Area of Science:
- Plasmonics
- Nanophotonics
- Biosensing
Background:
- Surface plasmons are widely used for biosensing applications.
- Gap plasmons offer potential for enhanced detection sensitivities.
- Understanding the comparative performance of gap and surface plasmons is crucial for optimizing sensor design.
Purpose of the Study:
- To investigate and compare the detection sensitivities of gap plasmons versus surface plasmons.
- To explore the influence of nanoslit width on gap plasmon sensitivity.
- To correlate high sensitivity with the interaction volume between biomolecules and plasmons.
Main Methods:
- Fabrication of gold nanoslit arrays with varying slit widths on a 130 nm-thick gold film.
- Characterization of transmission spectra for transverse-magnetic (TM) incident waves.
- Surface functionalization with silicon dioxide (SiO2) and various biomolecules to assess surface sensitivity.
Main Results:
- Two distinct transmission peaks were observed, corresponding to gap plasmon and surface plasmon resonances.
- Gap plasmons demonstrated significantly higher surface sensitivity compared to conventional surface plasmons.
- Sensitivity increased with decreasing slit width, with gap plasmons being an order of magnitude more sensitive for slits < 30 nm.
Conclusions:
- Gap plasmons in gold nanoslit arrays are superior to surface plasmons for detecting thin films and biomolecules.
- The enhanced sensitivity is attributed to the increased overlap between biomolecules and the confined nanometer-sized gap plasmons.
- Nanoslit width is a critical parameter for tuning and maximizing the sensing performance of gap plasmon sensors.
