Understanding the Shinyei PPD24NS low-cost dust sensor

Abstract

Air quality measurement is a topic of a great interest for any country due to health and environmental reasons. Tis issue is more critical in low-incomes countries since the air quality is generally worse than in developed countries and the governments give fewer budget to lead environmental policy and research. This explains the increasing demand for low-cost dust optical sensors like the Shinyei PPD24NS during the last years. However, those sensors present mixed results in terms of precision and repeatability, especially in case of new applications like the ones in moving context. Moreover, few or confuse information exists on those sensors functioning and conditions of use and the manufacturer does not provide any comprehensive guideline. The present article aims at filling this gap, providing a real study of the internal sensor operating. This includes: a detailed, theoretical and practical, analysis of the electric diagram, a characterization of the airflow through the optical chamber, an output behavior analysis based on particulate matter concentration and some algorithmic issues guideline. The article ends by providing useful tips and recommendations as well as some tracks to improve its precision for new applications.

Preliminary research for low-cost particulate matter sensor network

“…According to our previous research, fan-mounted sensors were preferred during tests, because the amount of air sucked in is less influenced by the weather and they are more reliable. Similar conclusion was reported by Canu et al [24]. The main goal of this paper is to test three different types of sensors from various aspects including reproducibility, design variations, sensors comparison and humidity influence.…”

Shinyei Based Sensor with Added Roof Enhanced Detection of Indoor Particulate Matter

“…If the sensor was in a horizontal position and the resistor was on, the temperature at the inlet would be higher compared to the outlet as the hot air from the resistor will rise and leave the sensor through the nearer aperture which is the inlet. It was recommended by Canu et al (2018) to place the sensor in a vertical position because in such a vertical position the hot air at the bottom of the resistor will rise upward and leave the sensor through the outlet [22].…”

What does the Shinyei PPD42NS Low-Cost Dust Sensor Really Measure?

“…There are also artifacts related to the chemical composition of the particles, which affect its refraction or diffusion properties, and its hygroscopicity. Moreover, the airflow stability inside the sensor can also affect the particle concentration estimation [22]. Sharp GP2Y1010AU0F, Shinyei PPD42N(S or J) and PPD60PV-T2, Syhitech DSM501A, Samyoung DSM501 or Amphenol/Telaire SM-PWM-01A are the most common used ultra-low-cost dust sensors in citizen proyects, and all of them use the same optical measurement principle.…”

“…The maximum gain of this filter is 616.6 (55.8dB) and the minimum phase shift is at 5.7 Hz. The filter attenuates frequencies lower than 0.135 Hz and higher than 1175 Hz, as calculated by Canu et al [22]. The two following OAMP cells constitute two inverted comparators that produce the two output pulse signals.…”