title: Fabrication of bimetallic microfluidic surface-enhanced Raman scattering sensors on paper by screen printing.
abstract: Au-Ag bimetallic microfluidic, dumbbell-shaped, surface enhanced Raman scattering (SERS) sensors were fabricated on cellulose paper by screen printing. These printed sensors rely on a sample droplet injection zone, and a SERS detection zone at either end of the dumbbell motif, fabricated by printing silver nanoparticles (Ag NPs) and gold nanoparticles (Au NPs) successively with microscale precision. The microfluidic channel was patterned using an insulating ink to connect these two zones and form a hydrophobic circuit. Owing to capillary action of paper in the millimeter-sized channels, the sensor could enable self-filtering of fluids to remove suspended particles within wastewater without pumping. This sensor also allows sensitive SERS detection, due to advantageous combination of the strong surface enhancement of Ag NPs and excellent chemical stability of Au NPs. The SERS performance of the sensors was investigated by employing the probe rhodamine 6G, a limit of detection (LOD) of 1.1×10(-13)M and an enhancement factor of 8.6×10(6) could be achieved. Moreover, the dumbbell-shaped bimetallic sensors exhibited good stability with SERS performance being maintained over 14 weeks in air, and high reproducibility with less than 15% variation in spot-to-spot SERS intensity. Using these dumbbell-shaped bimetallic sensors, substituted aromatic pollutants in wastewater samples could be quantitatively analyzed, which demonstrated their excellent capability for rapid trace pollutant detection in wastewater samples in the field without pre-separation.
authors.affiliation: State Key Laboratory of Bioreactor Engineering & Department of Chemistry, East China University of Science and Technology, Shanghai 200237, PR China.
authors.forename: Lu-Lu
authors.initials: LL
authors.lastname: Qu
authors.forename: Qi-Xia
authors.initials: QX
authors.lastname: Song
authors.forename: Yuan-Ting
authors.initials: YT
authors.lastname: Li
authors.forename: Mao-Pan
authors.initials: MP
authors.lastname: Peng
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Li
authors.forename: Li-Xia
authors.initials: LX
authors.lastname: Chen
authors.forename: John S
authors.initials: JS
authors.lastname: Fossey
authors.forename: Yi-Tao
authors.initials: YT
authors.lastname: Long
mesh_terms: D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D044085:Microfluidics; D008851:Micropore Filters; D010209:Paper; D011327:Printing; D015203:Reproducibility of Results; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D062065:Wastewater / Q000737:chemistry*
chemical_list: D006046:Gold; D012834:Silver; D062065:Wastewater
keywords: Bimetallic; Microfluidic sensors; Paper; Screen printing; Surface-enhanced Raman scattering