Functional Femtoliter Droplets for Ultrafast Nanoextraction and Supersensitive Online Microanalysis

Miaosi Li, Brendan Dyett, Haitao Yu, Vipul Bansal, Xuehua Zhang* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

39 Citations (Scopus)
11 Downloads (Pure)


A universal femtoliter surface droplet-based platform for direct quantification of trace of hydrophobic compounds in aqueous solutions is presented. Formation and functionalization of femtoliter droplets, concentrating the analyte in the solution, are integrated into a simple fluidic chamber, taking advantage of the long-term stability, large surface-to-volume ratio, and tunable chemical composition of these droplets. In situ quantification of the extracted analytes is achieved by surface-enhanced Raman scattering (SERS) spectroscopy by nanoparticles on the functionalized droplets. Optimized extraction efficiency and SERS enhancement by tuning droplet composition enable quantitative determination of hydrophobic model compounds of rhodamine 6G, methylene blue, and malachite green with the detection limit of 10−9 to 10−11 m and a large linear range of SERS signal from 10−9 to 10−6 m of the analytes. The approach addresses the current challenges of reproducibility and the lifetime of the substrate in SERS measurements. This novel surface droplet platform combines liquid–liquid extraction and highly sensitive and reproducible SERS detection, providing a promising technique in current chemical analysis related to environment monitoring, biomedical diagnosis, and national security monitoring.

Original languageEnglish
Article number1804683
Issue number1
Early online date28 Nov 2018
Publication statusPublished - 4 Jan 2019


  • UT-Hybrid-D
  • nanoextraction
  • on-line analysis
  • surface droplets
  • surface-enhanced Raman scattering (SERS)
  • microreactors
  • 22/4 OA procedure


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