Abstract: Microfabricated particulate matter (PM) monitors and fractionators within the PM monitors are provided. A primary channel of a vertical or out-of-plane fractionator receives air samples, comprising particles of varying sizes, from the external environment. The air samples then pass through a plurality of microfluidic channels, wherein inertial forces are applied within the microfluidic channels to separate the particles by size. The fractionator comprises a horizontal air outlet for particles having a size below a threshold size and a vertical air outlet for particles having a size above a threshold size. Thus, the proportion of PM in the air sample is reduced prior to deposition on a PM monitor. A virtual cyclone may also be provided that comprises a bend positioned at a flow path through a primary channel of the vertical microfabricated fractionator.

Abstract: Microfabricated particulate matter (PM) monitors and fractionators within the PM monitors are provided. A primary channel of a vertical or out-of-plane fractionator receives air samples, comprising particles of varying sizes, from the external environment. The air samples then pass through a plurality of microfluidic channels, wherein inertial forces are applied within the microfluidic channels to separate the particles by size. The fractionator comprises a horizontal air outlet for particles having a size below a threshold size and a vertical air outlet for particles having a size above a threshold size. Thus, the proportion of PM in the air sample is reduced prior to deposition on a PM monitor. A virtual cyclone may also be provided that comprises a bend positioned at a flow path through a primary channel of the vertical microfabricated fractionator.

Abstract: Microfabricated PM sensors measure concentrations of particulate matter (PM) in air. Some sensors improve the accuracy of measurements by accounting for the effect of ambient conditions (e.g., temperature or humidity) on mass-sensitive elements employed to determine a mass of the PM in a stream of air. Some sensors improve the accuracy of measurements by controlling humidity in the stream of air measured by mass-sensitive elements. Some sensors employ a plurality of mass-sensitive elements to extend the useful life of the PM sensor. Some sensors employ one or more mass-sensitive elements and heating elements to cause deposition and allow measurement of different sizes of PM. Some sensors can measure mass concentration of coarse PM in addition to fine PM in a stream of air. Some sensors control the flow rate of a stream of air measured by mass-sensitive elements. Some sensors include features to mitigate electromagnetic interference or electromagnetic signal loss.