Monitoring Early-Stage Nanoparticle Assembly in Microdroplets by Optical Spectroscopy and SERS

Andrew R. Salmon, Ruben Esteban, Richard W. Taylor, James T. Hugall, Clive A. Smith, Graeme Whyte, Oren A. Scherman, Javier Aizpurua, Chris Abell, Jeremy J. Baumberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)
93 Downloads (Pure)


Microfluidic microdroplets have increasingly found application in biomolecular sensing as well as nanomaterials growth. More recently the synthesis of plasmonic nanostructures in microdroplets has led to surface-enhanced Raman spectroscopy (SERS)-based sensing applications. However, the study of nanoassembly in microdroplets has previously been hindered by the lack of on-chip characterization tools, particularly at early timescales. Enabled by a refractive index matching microdroplet formulation, dark-field spectroscopy is exploited to directly track the formation of nanometer-spaced gold nanoparticle assemblies in microdroplets. Measurements in flow provide millisecond time resolution through the assembly process, allowing identification of a regime where dimer formation dominates the dark-field scattering and SERS. Furthurmore, it is shown that small numbers of nanoparticles can be isolated in microdroplets, paving the way for simple high-yield assembly, isolation, and sorting of few nanoparticle structures.

Original languageEnglish
Pages (from-to)1788–1796
Number of pages9
Issue number3
Early online date10 Feb 2016
Publication statusPublished - 6 Apr 2016


  • Dark-field spectroscopy
  • Microdroplets
  • Nanoparticle
  • SERS

ASJC Scopus subject areas

  • Biomaterials
  • Engineering (miscellaneous)
  • Biotechnology


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