Surface-enhanced Raman spectroscopy for on-site analysis: A review of recent developments

On-site identification and quantification of chemicals is critical for promoting food safety, human health, homeland security risk assessment, and disease diagnosis. Surface-enhanced Raman spectroscopy (SERS) has been widely considered as a promising method for on-site analysis due to the advantages of nondestructive, abundant molecular information, and outstanding sensitivity. However, SERS for on-site application has been restricted not only by the cost, performance, and portability of portable Raman instruments, but also by the sampling ability and signal enhancing performance of the SERS substrates. In recent years, the performance of SERS for on-site analysis has been improved through portable Raman instruments, SERS substrates, and other combined technologies. In this review, popular commercial portable Raman spectrometers and the related technologies for on-site analysis are compared. In addition, different types of SERS substrates for on-site application are summarized. SERS combined with other technologies, such as electrochemical and microfluidics are also presented. The future perspective of SERS for on-site analysis is also discussed.