SERS and Microfluidics

Abstract

Conventional Raman spectroscopy has been established as a valuable tool for spectroscopy of organic and inorganic molecules. Because of the low efficiency of the Raman scattering process, this technique is limited to samples with a high concentration of analyte molecules. The utilization of the effect of surface enhancement of the Raman scattering increases the limits of detection up to 10 orders in magnitude. Surface-enhanced Raman scattering (SERS) benefits from this effect and enables investigation of small populations of molecules down to the single-molecule level. SERS has become a valuable method for the non-destructive investigation of small population of molecules, which meets the requirements for micro and trace analytics, metabolomics, biomedical applications and monitoring of contaminants in the food industry.This way, SERS is well suited for accessing multidimensional information from the tiniest objects and analytical samples. For automation, these samples must be placed, metered and processed close to the microscopic detection area. Moreover, the required steps for the preparation of such small samples and objects must be realized close to the detection region. Microfluidic approaches offer a rich and highly customizable set of procedures and operation units for sample processing at the microscale. These procedures benefit from the small characteristic dimensions and the well-controlled operations at the microscale. For implementation of a particular protocol, these operation units can be combined in lab-on-a-chip devices that implement a complete analytical or microchemical process.This chapter introduces the lab-on-a-chip technology and its application for SERS-based analytics. Recent application examples are given and discussed for the different microfluidic platforms.Lab-on-a-chip devices for SERS typically implement a user-defined process protocol for sample preparation and delivery of the sample to a microscale optical detection window for the readout of information by Raman spectroscopy (Figure 8.1). This way, the combination of lab-on-a-chip technology with SERS provides a valuable tool for automation and improvements of the reproducibility of Surface Enhanced Raman Spectroscopy: Analytical, Biophysical and Life Science Applications. Edited by Sebastian Schlücker

Microfluidics and surface-enhanced Raman spectroscopy, a win–win combination?

“…Among these analytical techniques, SERS has gained a reputation as a powerful optical technique by enabling the label-free detection of chemical and biological molecules. 46–48 Fig. 2A shows typical SERS detection of analytes adsorbed on gold nanoparticles (AuNPs) in a microfluidic channel.…”