Abstract
Ambient suspended particulate matter (PM) (primarily with particle diameter 2.5 µm or less, i.e., PM2.5) can adversely affect ecosystems and human health. Currently, optical particle sensors based on light scattering dominate the portable PM sensing market. However, the light scattering method has poor adaptability to different-sized PM and adverse environmental conditions. Here, we design and develop a portable PM sensing microsystem that consists of a micromachined virtual impactor (VI) for particle separation, a thermophoretic deposition chip for particle collection, and an extended-gate field-effect transistor (FET) for particle analysis. This system can realize on-site separation, collection, and analysis of aerosol particles without being influenced by environmental factors. In this study, the design of the VI is thoroughly analyzed by numerical simulation, and mixtures of different-sized silicon dioxide (SiO2) particles are used in an experimental verification of the performance of the VI and FET. Considering the low cost and compact design of the whole system, the proposed PM analysis microsystem has potential for PM detection under a wide range of conditions, such as heavily polluted industrial environments and for point-of-need outdoor and indoor air quality monitoring.
Highlights
Aerosol particulate pollution has serious impacts on ecosystems and human health
The separated PM2 is collected and analyzed by an extended-gate field-effect transistor (EGFET) in which a gold auxiliary electrode is connected to the gate terminal of a conventional metal–oxide–semiconductor field-effect transistor (MOSFET), which can directly measure the charges of the deposited particulate matter (PM).19
A combined PM analysis microsystem consisting of a PM separation device based on a virtual impactor (VI) and a PM detection module based on an FET has been described here
Summary
Aerosol particulate pollution has serious impacts on ecosystems and human health. The most obvious direct impact of particulate matter (PM) suspended in the atmosphere is a reduction in visibility, causing a high degree of inconvenience in daily activities. Sensors based on a light scattering mechanism determine particle concentration by measuring the scattered light from a combination of all the particles in one or more angles.14,15 Such devices have sufficient sensitivity to detect PM; their responses are dominated by large particles and are strongly dependent on. The separated PM2 is collected and analyzed by an extended-gate field-effect transistor (EGFET) in which a gold auxiliary electrode is connected to the gate terminal of a conventional metal–oxide–semiconductor field-effect transistor (MOSFET), which can directly measure the charges of the deposited PM.. The separated PM2 is collected and analyzed by an extended-gate field-effect transistor (EGFET) in which a gold auxiliary electrode is connected to the gate terminal of a conventional metal–oxide–semiconductor field-effect transistor (MOSFET), which can directly measure the charges of the deposited PM.19 Both the VI and EGFET can be mass-producible and are replaceable. Our results suggest that the proposed microsystem has potential for accurate real-time analysis of PM2 containing mixed particles in complex environments
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