Optical trapping-assisted SERS platform for chemical and biosensing applications: Design perspectives

Useful approaches to tackle Brownian motion of micro/nanoparticles and overcome the poor reproducibility of surface-enhanced Raman scattering (SERS) events are highly desirable, especially for performing SERS sensing in ultra-low concentration of analytes. When integrated with the SERS measurement system, optical trapping is a versatile approach for manipulating particles and thereby improving the SERS performance. A review of the recent research advancements in optical trapping-assisted SERS platform can provide critical inputs for optimizing SERS-based sensing methods for real-life applications. In this paper, we present an in-depth review on the systematic classification of optical trapping-assisted (e.g., far-field and near-field optical tweezers) SERS sensing platform and discuss its latest practical applications in biosensing, bioimaging, chemical monitoring, particle manipulation, single cell analysis, etc. Also, we summarize some important strategies to suppress the plasmonic heating effect which hinders the stability of optical tweezers. Furthermore, we also propose non-optical trapping approaches for manipulating nanoparticles/molecules that are promising for prospective SERS sensing. For example, plasmonic heating is not completely deleterious to particle manipulation. Particularly, plasmon-enhanced thermophoresis technique is a useful non-optical approach for trapping particles/molecules and incorporating with SERS detection. Finally, we conclude with future perspectives for designing the new generation of optical tweezers.