Condensation associated with the collection and identification of airborne particles is detected. Upon the detection, one or more condensation countermeasures are triggered to address the condensation.

The invention relates to a method and an apparatus for measuring particle concentrations in an aerosol. The apparatus comprises means (103) for driving flow (105) into apparatus (101), means (115) for electrically charging particles (109) to become electrically charged particles (123) by ions (113) produced by a charger, means (117) for removing free ions (113) which are not attached to the electrically charged particles (123), and means (119) for measuring electrical current carried by the electrically charged particles (123). The means (115) for charging the particles and the means (119) for measuring electrical current carried by the electrically charged particles (123) are dimensioned such that the means (119) for measuring electrical current carried by the electrically charged particles (123) only measures a part of a total current carried by the particles.

A soot sensing system includes a soot sensor having a first element, and circuitry to an amount of soot accumulated on the element and to control heating of the element in response to the soot accumulation. An electrostatic repelling voltage (ERV) may be applied to a sensor/heater element(s) during a contamination prevention mode (CPM) to repel ash and reduce contamination of the sensor. A pulsed heating voltage (PHV) may be applied to the elements during the CPM and a pulsed ERV may be applied to the elements during the “off” period of the PHV. All voltage to the elements may be turned off during the CPM and the elements may be floating/ground. A PHV may be applied to the elements during the CPM and no voltage may be applied to the elements during the “off” period of the PHV. A heating voltage may be applied to the elements during a CPM corresponding to a cold start.

Apparatus and associated methods relate to monitoring air quality. At least one of temperature, humidity, and particulate concentrations is measured by an indoor air quality monitor, which may be disposed in a spot location. Air from that spot location is drawn into the housing of the indoor air quality monitor via a fan assembly. The air drawn into the housing is directed passed at least one of a temperature sensor, a humidity sensors, and a particulate detector. The air is then expelled back outside the housing through an outlet in a non-planar upper surface of the housing. A processor generates the indoor air quality summary based on the measured temperature, humidity, and particulate concentration.

An opposed migration classifier classifies particles suspended in a sample fluid that are passed through a classification channel defined by two permeable walls. Sample flow distribution input and output channels are located asymmetrically with respect to a center of the classification channel such that trajectories of the one or more particles in the sample fluid deviate from constant voltage operation trajectories. A cross-flow fluid enters the classification channel through a permeable wall and exits through the other permeable wall. An imposed field, created by a time varying filed imposed in a direction normal to the permeable walls, causes the particles to migrate in a direction opposite to that of the cross-flow fluid, such that the particles travel between the permeable walls. The particles in the sample are classified based on their mobility. The sample fluid enters and exists through or within a threshold distance of the permeable walls.

A method and system of determining a filter life are disclosed. In examples, a method comprises capturing aerosol particles on a filter and measuring absorbance spectra of the aerosol particles captured on the filter. The method further comprises identifying one or more aerosol particle types based on the measured absorbance spectra and determining a mass accumulation of each of the one or more aerosol particle types based on the measured absorbance spectra and the aerosol particle type. The method further comprises determining a median particle size of each of the one or more aerosol particle types based on the measured absorbance spectra and the aerosol particle type and determining a filter life based on the determined mass accumulation and the determined median particle size of each of the one or more aerosol particle types.

A method and system of determining air quality are disclosed. In examples, a method comprises identifying one or more aerosol particle types based on an absorbance spectra of aerosol particles captured on a filter and determining a mass concentration of each of the one or more aerosol particle types based on the absorbance spectra and the aerosol particle type. The method further comprises detecting a median particle size of each of the one or more aerosol particle types based on a rate of change of the absorbance spectra and the aerosol particle type. The method further comprises determining an air quality metric based on the identified one or more aerosol particle types, the determined mass concentration of each of the one or more aerosol particle types, and the determined median particle size of each of the one or more aerosol particle types.

Apparatus and methods are disclosed which are capable of being used to determine filtration efficiency of a filter body even in a clean state. Methods of determining a filtration efficiency of a filter including forcing an inlet flow comprised of a gas (such as air) flow into the inlet end of the filter at a set flow rate, introducing particles such as smoke particles into the inlet flow, and optically counting the number of particles entering and exiting the filter during a sampling event, such as with diffraction based optical particle counters positioned upstream and downstream of the filter. Preferably the gas flow is a soot-free flow stream which does not load the honeycomb filter body with contaminants that need to be removed or burned out. The filter body can thus remain in an essentially clean state even after testing its filtration efficiency.

Systems and methods are provided for reliably detecting aerosolized virus particles using electrochemical characteristics of the virus, and its interaction with π-conjugated conducting solid-state substrates.

A laser sensor module for detecting a particle density of small particles with a particle size between 0.05 μm and 10 μm includes a first laser configured to emit a first measurement beam, a second laser configured to emit a second measurement beam, and an optical arrangement configured to focus the first measurement beam to a first measurement volume and to focus the second measurement beam to a second measurement volume. The optical arrangement includes a first numerical aperture and a second numerical aperture arranged to detect a predetermined minimum particle size. The laser sensor module further includes a first detector configured to determine a first self-mixing interference signal of a first optical wave, a second detector configured to determine a second self-mixing interference signal of a second optical wave, and an evaluator.