A flexible surface-enhanced Raman Spectroscopy chip integrated with microlens

A novel flexible Surface-enhanced Raman Spectroscopy (SERS) chip integrated with microlens was proposed and designed, which consisted of PDMS film, planoconvex microlens, and silver nanoparticles (AgNPs) monolayer, and was of high signal collection efficiency. The flexible PDMS film integrated with microlens was designed by optical simulation, and fabricated by optimized micromachining process. AgNPs monolayer were uniformly assembled on the other side of the PDMS film through a liquid-liquid interface self-assembly method to form SERS chip. The prepared chip revealed excellent SERS performance with a Raman enhancement factor of about 107 and a signal variation of <11.5 %. The SERS chip was successfully utilized for in-situ detection of thiram residues on tomato skins, and its characteristic peaks could still be clearly distinguished when the concentration was down to 2.5 μM. It was shown that the proposed SERS chip was suitable for in-situ detection of a real sample on complex surface morphology and shown potential prospect in the fields of chemical and biomedical detections.