A SERS and electrical sensor from gas-phase generated Ag nanoparticles self-assembled on planar substrates

Area of Science:

• Plasmonics
• Nanotechnology
• Chemical Sensing

Background:

• Coupled plasmonic nanoparticles create localized electromagnetic "hot-spots" crucial for surface-enhanced spectroscopies like SERS.
• SERS is a highly sensitive technique with significant potential in various sensing applications.
• Developing robust and tunable SERS substrates is key to advancing sensing capabilities.

Purpose of the Study:

• To present a novel chemical sensor with dual SERS and electrical transduction capabilities.
• To investigate the broad tunability of localized surface plasmon resonance (LSPR) in self-assembled silver nanoparticle monolayers.
• To demonstrate the high SERS enhancement factor and uniformity of the developed sensor.

Main Methods:

• Fabrication of a close-packed plasmonic monolayer thin-film of gas-phase generated silver nanoparticles on glass slides.
• Control of nanoparticle deposition time to tune plasmonic coupling and LSPR.
• Characterization of SERS activity and electrical sensing performance using 4-mercaptobenzonitrile (4-MBN).

Main Results:

• Achieved a SERS enhancement factor (EF) of 10^7 with the close-packed monolayer sensor.
• Demonstrated broad LSPR tunability across visible to near-infrared wavelengths.
• Observed significantly lower SERS performance in sub-monolayer or multi-layer films.
• Confirmed high uniformity and batch-to-batch reproducibility of the sensor.

Conclusions:

• The close-packed plasmonic nanoparticle monolayer thin-film sensor exhibits excellent SERS performance, uniformity, and reproducibility.
• The dual transduction capability and tunable LSPR make it suitable for quantifiable detection of chemical and biological molecules.
• This sensor offers a cost-effective and reliable platform for identifying chemical and biological threats in security applications.