AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Multi-Electrometer Detector for Real–Time High-Resolution Measurements in Planar Differential Mobility Analyzers
LUIS-JAVIER PEREZ-LORENZO, Mario Amo-Gonzalez, Juan Fernandez de la Mora, Yale University
Abstract Number: 485 Working Group: Instrumentation and Methods
Abstract Differential Mobility analyzers (DMAs) select a narrow range of particle mobilities in mixtures, determining mobility-distributions via voltage scans. To obtain high-resolution mobility spectra without scanning, we have distributed 100 electrically insulated charge-collecting strips over one electrode of a parallel plate DMA. All collected currents are sampled simultaneously, accelerating 100-fold the measurement. Initial tests with 8-detectors showed that suitably designed small steps in the insulating gaps between detectors do not induce turbulence. This development is particularly useful for high-resolution tandem DMA studies, typically requiring a grid of some 100x100 data points, and taking between 16.7 to 167 minutes. Incorporating the new detector into the second DMA makes the acquisition of tandem spectra as fast as current single spectrum acquisition (10-100 s), enabling a diversity of scientific investigations, such as the study of the evolution of small clusters. Another peculiarity of this DMA is that the usual finite sample flow rate at the outlet slit is null. The inlet sample flow rate can also be null in a parallel plate DMA, where charged particles may be injected by an external electric field. Therefore, the familiar inlet and outlet sample flow dependencies of the DMA size range and sensitivity no longer apply. Because the spectrum is obtained at fixed voltages, transmission corrections at the inlet and outlet are also simpler to implement than in scanning DMAs.
This work was funded by SEADM, partly through the European Commission FEDER (ERDF) Program (project “DMA Multipixelado” – Subprogram: “Proyectos en I+D en PYMES, file number 04/16/VA/0008”). We acknowledge Irene Carnicero’s contributions to the fabrication of the lower DMA electrode