A self-driven microfluidic surface-enhanced Raman scattering device for Hg2+ detection fabricated by femtosecond laser†
In this paper, we proposed a novel approach for rapid and flexible fabrication of self-driven microfluidic surface enhanced Raman scattering (SERS) chips for quantitative analysis of Hg2+ by femtosecond laser direct writing. In contrast to traditional microfluidic chips, the microchannels of the device can drive a liquid sample flow without external driving force. The sample flow speed is tunable since the wettability and capillarity properties of the channels, which depend on the roughness and the inner diameter of the microchannels, can be controlled by optimizing the laser processing parameters. The SERS active detection sites, which exhibit high enhancement effects and fine reproducibility, were integrated through the femtosecond laser-induced periodic surface structures (LIPSS), followed by 30 nm Ag deposition. The SERS performance of the as-prepared microfluidic SERS detection chip was studied with R6G as probe molecules. The quantitative analysis of Hg2+ was realized by simply injecting the Hg2+ sample and the probe molecules R6G from the two inlets, separately, and collecting the SERS signal at the detection site. The lowest detection limit for Hg2+ is 10−9 M. It should be mentioned that this study is not only limited to Hg2+ quantitative analysis, but is also mainly aimed to develop a new technique for the design and fabrication of novel self-driven microfluidic devices depending on practical application requirements.