TY - JOUR
T1 - Thermophoretic Sampler and its Application in Ultrafine Particle Collection
AU - Wen, Jian
AU - Wexler, Anthony S.
PY - 2007/5/3
Y1 - 2007/5/3
N2 - 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.
AB - 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.
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U2 - 10.1080/02786820701278456
DO - 10.1080/02786820701278456
M3 - Article
AN - SCOPUS:85012539461
VL - 41
SP - 624
EP - 629
JO - Aerosol Science and Technology
JF - Aerosol Science and Technology
SN - 0278-6826
IS - 6
ER -