Surface-enhanced Raman scattering sensors for biomedical and molecular detection applications in space

Area of Science:

• Nanotechnology
• Spectroscopy
• Environmental Science

Background:

• Detecting molecular traces, especially Volatile Organic Compounds (VOCs), is critical for safety in aerospace, food production, and medical diagnostics.
• Existing methods face challenges in achieving the extreme sensitivity required for trace contaminant detection, often in the parts-per-billion (ppb) range.
• Poor affinity of VOCs to sensor substrates limits detection sensitivity.

Purpose of the Study:

• To develop a highly sensitive and selective molecular sensor for trace gas detection using surface-enhanced Raman scattering (SERS) spectroscopy.
• To create a hybrid SERS platform combining nanoplasmonic porous silicon membranes with a micropump for enhanced VOC detection.
• To overcome the limitations of traditional sensors by developing a system less sensitive to molecule adsorption on the sensing element.

Main Methods:

• Fabrication of a hybrid SERS platform using electrochemical etching of silicon to create microchannels, followed by silver nanoparticle deposition to form a porous nanoplasmonic membrane.
• Integration of a micropump to actively draw air containing VOCs through the nanoplasmonic membrane's "hot spots" to maximize molecule-SERS substrate interaction.
• Design and simulation of sensor chip structure and gas flow, followed by 3D printing fabrication of the sensor.

Main Results:

• Demonstrated limit of detection for hydrazine at 10⁻¹² M in solution and 0.1 ppm in the vapor phase.
• Successfully recorded spectra of anisole vapors at a concentration of 0.5 ppb in air.
• Achieved high enhancement factors for trace pollutant molecule detection with nanomolar sensitivity.

Conclusions:

• The developed plasmonic membrane SERS sensor offers high enhancement factors and nanomolar sensitivity for detecting various pollutant molecules.
• This technology is suitable for designing sensitive sensors for space applications, environmental monitoring, and biomedical diagnostics.
• The hybrid SERS platform effectively enhances the interaction probability of VOCs with the SERS substrate, enabling trace-level detection.