Particulate matter sensor

A sensor for detecting particulate matter (PM) pollutants, comprising:

• a body defining a channel configured to receive a stream of air from outside the body via via one or more fractionators configured to select for a particular size of PM;
• a plurality of mass-sensitive elements disposed in the channel, wherein:
• a first of the mass-sensitive elements is configured to receive a deposition of PM from the stream of air and to provide a first signal indicating a mass of the PM deposition;
• and
• a second of the mass-sensitive elements is configured to receive a second deposition of PM from the stream of air and to provide a second signal indicating a mass of the second PM deposition;
• and
• a plurality of heating elements, wherein:
• a first of the heating elements is proximate to the first mass-sensitive element and operable to produce a first temperature gradient that causes the first PM deposition on the first mass-sensitive element;
• a second of the heating elements is proximate to the second mass-sensitive element and operable to produce a second temperature gradient that causes the second PM deposition on the second mass-sensitive element,
• wherein the first mass-sensitive element and the second mass-sensitive element are alternately operated so that only one of the first mass-sensitive element or the second mass-sensitive element receives at a given time the first PM deposition or the second PM deposition, respectively.

A sensor for detecting particulate matter (PM) pollutants, comprising:

• a body defining a channel configured to receive a stream of air from outside the body via one or more fractionators configured to select for a particular size of PM;
• one or more mass-sensitive elements disposed in the channel;
• and
• a plurality of heating elements arranged in series in the channel and operable to produce a temperature gradient that causes at least one deposition of PM on one of the mass-sensitive elements,
• wherein a size of PM in the deposition received by the one mass-sensitive element is determined by the position of the one mass-sensitive element relative to the heating elements, and the mass-sensitive element is configured to provide a signal indicating a mass of the PM deposition.

A sensor for detecting particulate matter (PM) pollutants, comprising:

• a body defining a channel configured to receive a stream of air from outside the body via one or more fractionators configured to select for a particular size of PM, the stream of air passing through the channel at a flow rate;
• a mass-sensitive element configured to receive a deposition of PM from the stream of air and to indicate a mass of the PM deposition;
• an air pump coupled to the channel and operable at an adjustable speed that adjusts the flow rate of the stream of air in the channel;
• one or more sensors configured to determine and provide a signal indicating the flow rate in the channel;
• and
• circuitry coupled to the air pump and receiving the signal from the one or more sensors, the circuitry configured to control the flow rate in the channel by adjusting the speed of the air pump in response to the signal from the one or more sensors.

A sensor for detecting particulate matter (PM) pollutants, comprising:

• a body defining a plurality of channels configured to receive a stream of air from outside the body;
• and
• a plurality of mass-sensitive elements disposed in the plurality of channels, each mass-sensitive element configured to provide a signal indicating a mass of a respective deposition of PM from the stream of air,
• wherein the plurality of channels includes one or more major channels and a minor channel receiving the stream of air from one or more PM fractionators, the mass-sensitive elements include one or more first mass-sensitive elements and a second mass-sensitive element, the one or more first mass-sensitive elements being disposed in the one or more major channels, the second mass-sensitive element being disposed in the minor channel, the plurality of channels being configured to cause deposition of PM of a first size on the one or more first mass-sensitive elements and deposition of PM of a second size from the stream of air on the second mass-sensitive element.

A sensor for detecting particulate matter (PM) pollutants, comprising:

• a body defining a channel configured to receive a stream of air from outside the body into the channel via one or more fractionators configured to select for a particular size of PM;
• and
• at least one mass-sensitive element disposed in the channel and configured to receive a deposition of PM from the stream of air and to provide a measurement signal indicating a mass of the PM deposition;
• circuitry that receives the measurement signal from the at least one mass-sensitive element and is configured to process the measurement signal and determine a concentration of the PM in the stream of air, the circuitry generating an electromagnetic output signals associated with the determination of the concentration of the PM;
• and
• means for mitigating loss or noise in the electromagnetic output signals generated by the circuitry.

A sensor for detecting particulate matter (PM) pollutants, comprising:

• a body including at least a first layer and a second layer, the second layer defining a channel passing between the first layer and the second layer, the channel configured to receive a stream of air from outside the body;
• at least one mass-sensitive element disposed in the channel and configured to receive a deposition of PM from the stream of air and to provide a measurement signal indicating a mass of the PM deposition;
• and
• a fixture coupled to the body providing an inlet for the stream of air, the inlet configured to direct the stream of air into the channel along a plane defined by the second layer without passing through the first layer or the second layer.