Analysis of optical trap mediated aerosol coalescence

N. S. Mistry*, R. Power, S. Anand, D. McGloin, A. Almohamedi, M. Downie, J. P. Reid, A. J. Hudson

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingPublished conference contribution

1 Citation (Scopus)


The use of optical tweezers for the analysis of aerosols is valuable for understanding the dynamics of atmospherically relevant particles. However to be able to make accurate measurements that can be directly tied to real-world phenomena it is important that we understand the influence of the optical trap on those processes. One process that is seemingly straightforward to study with these techniques is binary droplet coalescence, either using dual beam traps, or by particle collision with a single trapped droplet. This binary coalescence is also of interest in many other processes that make use of dense aerosol sprays such as spray drying and the use of inhalers for drug delivery in conditions such as asthma or hay fever. In this presentation we discuss the use of high speed (∼5000 frames per second) video microscopy to track the dynamics of particles as they approach and interact with a trapped aqueous droplet and develop this analysis further by considering elastic light scattering from droplets as they undergo coalescence. We find that we are able to characterize the re-equilibration time of droplets of the same phase after they interact and that the trajectories taken by airborne particles influenced by an optical trap are often quite complex. We also examine the role of parameters such as the salt concentration of the aqueous solutions used and the influence of laser wavelength.

Original languageEnglish
Title of host publicationProceedings: Optical Trapping and Optical Micromanipulation IX
Publication statusPublished - 2012
EventSPIE NanoScience + Engineering : Optical Trapping and Optical Micromanipulation IX - San Diego, CA, United States
Duration: 12 Aug 201216 Aug 2012


ConferenceSPIE NanoScience + Engineering
Country/TerritoryUnited States
CitySan Diego, CA


  • Aerosols
  • Coalescence
  • Droplets
  • High-speed imaging
  • Light scattering
  • Optical tweezers


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