Development of a personal dust monitor with a piezoelectric quartz crystal sensor

Abstract

A monitoring system using the collection technique of electrostatic precipitation on to a piezoelectric sensing element is examined. The transduction mechanism is the change in the resonant frequency of the sensing element from its unloaded nominal value of 9 MHz caused by the collected dust. The monitor had the three main design areas (point-to-plane distance, precipitator voltage and electrode-to-dust-inlet distance) optimized at a flow rate of approximately 1 l min −1 . This led to collection efficiencies greater than 97% with crystal mass sensitivity constants in the range 30-130 Hz µg −1 for the aerosol Arizona Road Dust. The total sampling time is limited by overloading of the sensing element by dust. A method of extending the sampling time by using compressed air to clean the sensing element is described.

Measurement of PM2.5 Mass Concentration Using an Electrostatic Particle Concentrator-Based Quartz Crystal Microbalance

“…QCM-based instruments can be classified into two major categories based on particle capture mechanism: (i) inertial impaction [10], [14], [15], [19], [24], and (ii) external force based impaction (e.g. electrostatic force) [12], [13], [17], [18], [25], [26]. In the first one, the sensing electrode of the quartz crystal works as an impaction plate.…”

“…For these reasons, the QCM was combined with the electrostatic precipitator (ESP) [12], [13], [17], [18]. These instruments possess advantages in comparison with the inertial impaction-based QCMs.…”

A SAW oscillator for monitoring particulate matter in air

“…SAW devices are highly surface mass sensitive but are not intrinsically selective, however, they do have the potential to provide real-time measurement; the use of a SAW device for aerosol monitoring was demonstrated by Bowers et al (1991) using olive oil as the test aerosol. In a previous report, EP have been used in conjunction with quartz crystal microbalances (QCM), in a prototype personal dust monitor (Wilson et al 1997). In this article we demonstrate the feasibility of combining SAW and EP technologies with the size selection capability of the cyclone for real time particulate monitoring.…”

An EP-SAW for measurements of particulate matter in ambient air

“…[5] using olive oil as the test aerosol. In a previous report EP have been used in conjunction with quartz crystal microbalances (QCM), an acoustic wave device with a lower sensitivity than SAW devices, in a prototype personal dust monitor [6]. In this article we demonstrate the feasibility of combining SAW and EP technologies for real time particulate monitoring.…”