Improving a Commodity Dust Sensor to Enable Particle Size Analysis

This paper presents a design in which a common, off-the-shelf, low-cost dust sensor, normally aimed at providing the measurements of the total dust concentration, is employed as the core of a more sophisticated instrument, object of this design, which is able to measure also the particle size of sampled airborne particulate, thus providing the particle size analysis of the sampled air. This result has been achieved by introducing some modifications to the sensor's operating directions as specified by the manufacturer. These modifications mainly concern: a different geometry for the sampled air flow (to enable the detection of single particles), a more accurate processing of the output signal (to maximize the signal/noise ratio), and a simple yet an accurate metrological calibration, which exploits the statistical properties of commonly available polydispersed particulate (talc powder), instead of needing monodispersed material (expensive and difficult to employ). The experimental results show that, under the proper conditions, the calibrated instrument is indeed able to measure the optical size of the detected particles and therefore to determine the particle size distribution (i.e., the granulometric analysis) of the sampled particulate.