17 Jun 2022
17 Jun 2022
Status: this preprint is currently under review for the journal AMT.

Characterization of a modified printed optical particle spectrometer for high-frequency and high-precision laboratory and field measurements

Sabin Kasparoglu, Mohammad M. Islam, Nicholas Meskhidze, and Markus D. Petters Sabin Kasparoglu et al.
  • Department of Marine, Earth, and Atmospheric Sciences, NC State University, Raleigh, NC, 27695-8208, USA

Abstract. The Printed Optical Particle Spectrometer (POPS) is a lightweight, low-cost instrument for measurements of aerosol number concentrations and size distributions. This work reports on modifications of the Handix Scientific commercial version of the POPS to facilitate its use in multi-instrument aerosol sampling systems. The flow system is modified by replacing the internal pump with a needle valve and a vacuum pump. The instrument is integrated into closed-flow systems by routing the sheath flow from filtered inlet air. A high-precision multichannel analyzer (MCA) card is added to sample the analog pulse signal. The MCA card is polled at 10 Hz frequency using an external data acquisition system and improves upon the count-rate limitation associated with the POPS internal data acquisition system. The 90/10 rise and fall times for 10 Hz POPS data were measured to be 0.17 s and 0.41 s at a flow rate of 5 cm-3 s-1. This yields a sampling frequency of ~1–2 Hz below which the amplitude of measured fluctuations is captured with > 70 % efficiency. The modified POPS was integrated into the dual tandem differential mobility analyzer system, to explore the coalescence of dimer particles. Results show that the pulse-height response increases upon dimer coalescence. The magnitude of the increase is broadly consistent with the change in light scattering amplitude predicted by the T-matrix method. It is anticipated that this modified version of the POPS will extend the utilization of the technique for a range of field and laboratory applications.

Sabin Kasparoglu et al.

Status: open (until 03 Aug 2022)

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Sabin Kasparoglu et al.

Sabin Kasparoglu et al.


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Short summary
A modified version of a Handix Scientific’s Printed Optical Particle Spectrometer is introduced. The manuscript presents characterization experiments, including concentration-, size-, and time-responses. Integration of an external multichannel analyzer card removes counting limitations of the original instrument. It is shown that the high-resolution light-scattering amplitude data can be used to sense particle phase transitions.