Use of an electrical aerosol detector (EAD) for nanoparticle size distribution measurement
- First Online:
Recently, Nanoparticle Surface Area Monitor (NSAM, TSI model 3550) and EAD (EAD, TSI Model 3070A) have been commercially available to measure the integral parameters (i.e., total particle surface area and total particle length) of nanoparticles. By comparison, the configuration of the EAD or NSAM is similar to that of electrical mobility analyzer of the early generation for particle size distribution measurement. It is therefore possible to use the EAD or NSAM as a particle sizer. To realize the objective of using the EAD as a sizer, we characterized the average electrical charges of monodisperse particles passing through the EAD particle charger and ion trap set at voltages ranging from 20 to 2500 V. The average charge data collected at different ion-trap voltages were then summarized by the empirical correlation using the parameter of Zp*V, where Zp is the particle electrical mobility and V is the ion-trap voltage. A data-reduction scheme was further proposed to retrieve the size distribution of sampled particles from the EAD readout at different ion-trap voltages. In the scheme, the functional format of each mode in a number size distribution of particles was assumed as log-normal, but the number of modes in an entire size distribution is not limited. A criterion was used to best fit the simulated EAD readouts with experimental ones by varying the count median diameter (CMD), geometric standard deviation (σg), and total particle number (Nt) of each mode in a particle size distribution. Experiments were performed to verify the proposed scheme.
KeywordsNanoparticle sizer Electrical aerosol detector Nanoparticle surface area monitor EAD unipolar charger Nanotechnology Occupational health EHS
- Hinds W (1999) Aerosol technology: properties, behavior, and measurement of airborne particles. Wiley-Interscience, New YorkGoogle Scholar
- Patashnick H, Rupprecht EG (1991) Continuous PM–10 measurements using the tapered element oscillating microbalance. J Air Waste Manage Assoc 41:1079–1083Google Scholar
- Wilson WE, Han HS, Stanek J, Turner J, Chen DR, Pui DYH (2004) Use of electrical aerosol detector as an indicator for the total particle surface area deposited in the lung. Symposium on air quality measurement methods and technology sponsored by the Air and Waste Management Association. Research Triangle Park, NC. Paper #37Google Scholar
- Woo KS, Chen DR, Pui DYH, Wilson WE (2001) Use of continuous measurements of integral aerosol parameters to estimate particle surface area. Aerosol Sci Technol 34:57–65Google Scholar