Tunable optical metamaterial-based sensors enabled by closed bipolar electrochemistry

Area of Science:

• Nanophotonics and Metamaterials
• Electrochemistry
• Chemical Sensing

Background:

• Optical metamaterials enable manipulation of light via sub-wavelength structures.
• Electrochemical tuning offers a method to modify material properties post-fabrication.

Purpose of the Study:

• To develop and characterize a chemical sensing approach using electrochemically tuned nanoaperture metamaterials.
• To demonstrate optical coulometry for analyte detection with enhanced sensitivity.

Main Methods:

• Fabrication of large-area nanoaperture metamaterials using nanosphere lithography.
• Electrochemical tuning of optical response via silver electrodeposition in a closed bipolar electrochemical cell.
• Optical transmission spectroscopy for monitoring spectral shifts under galvanostatic conditions.

Main Results:

• Tunable shifts in transmission spectra achieved by altering aperture size, film thickness, and composition.
• Sigmoidal response observed with respect to deposited charge, enabling optical coulometry.
• Enhanced sensitivity for detecting analytes in the μM to nM range compared to electrochromic reporters.

Conclusions:

• Developed tunable nanoaperture metamaterials offer a sensitive platform for chemical sensing.
• The architecture is suitable for optical coulometry and expanding closed bipolar electrochemical sensor capabilities.
• Potential applications include inexpensive, point-of-care diagnostic devices.