Micro electrical mobility classifier

摘要

The resolution of differential mobility classifiers is limited by Brownian diffusion when the ratio of the electrostatic potential energy of the migrating particles,eV,approaches the thermal energy,kT.Only when the DMA is operated at high voltages can particles be classified effectively.This can be expressed in terms of a migration Peclet number,Pe_(mig)=eV/kT The high mobilities of particles in the low nanometer size regime lead to operation of conventional DMAs either at low voltages,limiting resolution,or at very high flow rates.As the flow Reynolds number becomes large,the onset of turbulence within the classification region quickly degrades resolution.De la Mora and coworkers have,however,convincingly demonstrated that careful aerodynamic design of the sheath air inlet of a DMA can enable operation at the high Reynolds numbers required for high resolution classification of particles in the low nanometer size regime.