Development and performance test of a ZnO nanowire charger for measurements of nano-aerosol particles

The most efficient and widely used technique for monitoring aerosol particles is essentially an electrical method. For the development of any miniaturized aerosol classifier based on electrical techniques the miniaturized aerosol charger must provide a sufficient and stable charging efficiency. We designed and fabricated a ZnO nanowire charger (4 cm length × 2 cm width × 1 cm height) and then carried out an aerosol particle charging performance test. To test the electrical characteristics of this charger, corona currents were measured according to various applied voltages to determine the maximum stable ion number concentration. The average particle charge and wall loss of the charger were evaluated with monodispersed NaCl aerosol particles with diameters of 15-80 nm. The particle charge and wall loss were also obtained utilizing FLUENT (version 6.3), a commercial computational fluid dynamics (CFD) software, with an external user-defined function (UDF) code, by solving equations for the electric field, flow field, and particle trajectories. The measured data for particle loss and particle charge were in good agreement with the results calculated by FLUENT.