Extending the Lifetime of Resonant Atmospheric Particulate Mass Sensors With Solvent Rinses

Abstract

The cleaning of a collection-based sensor extends its lifetime and reduces its effective cost. Existing cleaning regimes for silicon-based devices typically require access to large laboratory equipment. A simple cleaning method based on solvent rinses is presented here for the application of microresonator atmospheric particulate mass sensors. The suggested approach is intended for scenarios with limited access to laboratory equipment. Two piezoelectric resonator topologies (in-plane bulk mode and out-of-plane flexural) collected particles via impaction for an hour before rinsing. The solvent rinses reset the resonant frequency and quality factor of each resonator to within 0.4% and 10% of their original values, respectively. Subsequent mass collections were largely repeatable despite fluctuations in particle concentration and deposition location. The presented method provides a straightforward but effective cleaning method for soluble particulate removal. A physical cleaning method is required after substantial insoluble particle adsorption.

Measuring Aerosol Phase Changes and Hygroscopicity with a Microresonator Mass Sensor

“…Images of the resonator collection surface ( Figure S-1) before NaCl collection and before NaCl/MA (i.e. after cleaning) are qualitatively similar and contrast with particle-laden surfaces as shown in Zielinski et al 41 . The cleaning approach is safe and minimally invasive compared to current alternatives including ultrasonication, CO2 snow jets, and the use of sacrificial coating layers 42 .…”

“…Between NaCl and NaCl/MA collection, the resonator was cleaned with methanol and water using a solvent rinsing technique described elsewhere. 41 Following cleaning, the resonant frequency was recovered to within 20 Hz (<1 ng) of the original clean frequency (Table S- 1). Images of the resonator collection surface (Figure S-1) before NaCl collection and before NaCl/MA (i.e., after cleaning) are qualitatively similar and contrast with particleladen surfaces as shown in Zielinski et al 41 The cleaning approach is safe and minimally invasive compared to current alternatives including ultrasonication, CO 2 snow jets, and the use of sacrificial coating layers.…”

“…Each salt was collected for one hour; the same resonator was used for both NaCl and NaCl/MA, with a different resonator of the same design used for AS. Between NaCl and NaCl/MA collection the resonator was cleaned with methanol and water using a solvent rinsing technique described elsewhere 41 . Following cleaning, the resonant frequency was recovered to within 20 Hz (<1 ng) of the original clean frequency (Table S- 1).…”

Compositional Analysis of Adsorbed Organic Aerosol on a Microresonator Mass Sensor

“…Presented m/z range (150-900) is for overlapping ranges of LESA (100-900) and filter extraction (150-1000) MS acquisition. DTAA: diaterpenylic acid acetate, MBTCA: Methylbutane-1,2,3-tricarboxylic acid reuse the resonator for multiple collections and reduce its effective cost (Zielinski et al 2017).…”

“…The requirement of particle deposition limits the lifetime of the device (Mehdizadeh et al 2017), but in turn enables the potential for additional analysis on the collected aerosol similar to filter or conventional impactor samples. After the additional analysis is complete, microresonators can be regenerated using a number of cleaning methods presented in the literature (Mehdizadeh et al 2017;Wasisto et al 2013Wasisto et al , 2013Wasisto et al , 2015Zielinski et al 2017) and reused for further measurements.…”