A flexible surface-enhanced Raman Spectroscopy chip integrated with microlens.

Area of Science:

• Materials Science
• Spectroscopy
• Nanotechnology

Background:

• Surface-enhanced Raman Spectroscopy (SERS) is a powerful technique for molecular detection.
• Improving signal collection efficiency and chip flexibility is crucial for practical SERS applications.
• Detection of pesticide residues on complex surfaces remains a challenge.

Purpose of the Study:

• To design and fabricate a novel flexible SERS chip integrated with a microlens.
• To evaluate the SERS performance and stability of the developed chip.
• To demonstrate the chip's capability for in-situ detection of thiram residues on tomato skins.

Main Methods:

• Optical simulation and micromachining were used to design and fabricate a flexible PDMS film integrated with a planoconvex microlens.
• Silver nanoparticles (AgNPs) monolayer were assembled on the PDMS film via a liquid-liquid interface self-assembly method.
• The chip's SERS performance was characterized using Raman enhancement factor and signal variation measurements. In-situ detection of thiram on tomato skins was performed.

Main Results:

• The flexible SERS chip exhibited high signal collection efficiency.
• A Raman enhancement factor of approximately 10^7 and signal variation below 11.5% were achieved.
• The chip successfully detected thiram residues on tomato skins down to 2.5 μM concentration.

Conclusions:

• The proposed flexible SERS chip with integrated microlens demonstrates excellent SERS performance and stability.
• The chip is suitable for in-situ detection on complex surfaces, such as tomato skins.
• This technology holds significant potential for future chemical and biomedical detection applications.