Surface-enhanced Raman spectroscopic system combined with dielectrophoresis using nanostructured microfluidic chip

Abstract

When a microparticle is exposed to an alternating current (AC) electric field, the polarized particle is moved by the interaction between the dipoles and the AC electric field under dielectrophoresis (DEP). The DEP force is widely used for manipulation of microparticles in diverse practical applications such as 3D manipulation, sorting, transfer, and separation of various particles such as living cells. In this study, we propose integration of surface-enhanced Raman spectroscopy (SERS), an extremely sensitive and versatile technique based on Raman scattering of molecules supported by nanostructured materials, with DEP using a microfluidic device, i.e., the microfluidic device combines metal nanostructures and microelectrodes to characterize electrophysiological and biochemical properties of biological cells. The movement of particles, which varies depending on the electrical properties such as conductivity and permittivity of particles, can be manipulated by the cross-frequency change, which is one of the DEP properties. Raman spectroscopy using this DEP-SERS integrated system can be performed with an improved signal-to-noise ratio by determining the direction of the DEP force applied to the cells with respect to the applied AC power and collecting them on the nanostructure.