title: Inkjet-printed paper-based SERS dipsticks and swabs for trace chemical detection.
abstract: We demonstrate a paper-based surface swab and lateral-flow dipstick that includes an inkjet-printed surface-enhanced Raman spectroscopy (SERS) substrate for analyte detection. Due to capillary-action wicking of cellulose, the paper dipstick enables extremely simple and pump-free loading of liquid samples into the detection device, and in addition provides inherent analyte concentration within the detection volume. Furthermore, the flexible nature of the paper-based SERS device also enables it to act as a swab to collect analyte molecules directly from a large-area surface; the collected analyte molecules can then be focused into a small-volume SERS-active region by lateral-flow concentration. These capabilities are unseen in today's SERS substrates and microfluidic SERS devices. Using these novel lateral-flow paper SERS devices, we achieved detection limits as low as 95 fg of Rhodamine 6G (R6G), 413 pg of the organophosphate malathion, 9 ng of heroin, and 15 ng of cocaine. Moreover, the measurements show that the technique is quantitative and is repeatable across multiple swabs and dipsticks. The results reported here may lead to ultra-low-cost portable applications in trace chemical detection.
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA.
authors.forename: Wei W
authors.initials: WW
authors.lastname: Yu
authors.forename: Ian M
authors.initials: IM
authors.lastname: White
mesh_terms: D002197:Capillary Action; D003042:Cocaine / Q000032:analysis*; D003932:Heroin / Q000032:analysis*; D010209:Paper; D011327:Printing; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D003932:Heroin; D003042:Cocaine