Thermophoretic Sampler and its Application in Ultrafine Particle Collection

Jian Wen, Anthony S. Wexler

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

A thermophoretic sampler is designed for the collection of particles smaller than 10 nm. The sampler is composed of heated and cooled surfaces separated by a gap of 0.1 mm; a bypass flow is introduced in the design to minimize the diffusional loss of nanoparticles in the upstream flow channel. Particles may be directly deposited on a 3 mm diameter TEM grid for chemical analysis or on other substrates for other purposes. Calculations show that at an inlet flow rate of 1.5 lpm and thermal gradient of 5 × 105 K/m, a maximum collection efficiency of 41% can be achieved for a particle diameter of 1 nm. Ag particles with median size of 6 nm are used to characterize the thermophoretic sampler collection efficiency. The TEM images show that a sizeable number of particles less than 10 nm in diameter are collected, although they are not uniformly distributed on the grid, and the collection efficiency deduced from these deposited particles is much less than the theoretical estimation. Despite this, the efficiency is orders of magnitude higher than previous designs and it is easier to build.

Original languageEnglish (US)
Pages (from-to)624-629
Number of pages6
JournalAerosol Science and Technology
Volume41
Issue number6
DOIs
StatePublished - May 3 2007

ASJC Scopus subject areas

  • Environmental Chemistry
  • Materials Science(all)
  • Pollution

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