A system includes a first and second condensation particle counter, each counter having an inlet port, a growth column, and an optical element for counting particles detected at the respective inlet ports. The counters are configured to include a wick in which the wick is wetted by water. A differential pressure sensor is coupled to the first inlet port and coupled to the second inlet port. The sensor is configured to provide a pressure signal. A processor is coupled to memory and configured to receive the first signal, the second signal, and the pressure signal and generate an output corresponding to a ratio of the first signal and the second signal and correlate the ratio with the pressure signal. A housing is configured to receive the first counter, the second counter, the differential pressure sensor, the processor, and the memory.

Various embodiments include methods and apparatuses to reduce false-particle counts in a water-based condensation particle counter (CPC). In one embodiment, a cleanroom CPC has three parallel growth tube assemblies. A detector is coupled to an outlet of each of the three parallel growth tube assemblies, and is used to compare the particle concentrations measured from each of the three growth tube assemblies. An algorithm compares the counts from the three detectors and determines when the particles counted are real and when they are false counts. Any real particle event shows up in all three detectors, while false counts will only be detected by one detector. Statistics are used to determine at which particle count levels the measured counts are considered to be real versus false. Other methods and apparatuses are disclosed.

A particle concentration analyzing system for testing particle concentrations in a fluid sample, such as engine emission particle concentration present in the exhaust of an engine. The particle concentration analyzing system includes a condensation particle counter having a saturation chamber, a condenser, and a laser optic particle counter. The analyzing system further includes a working fluid tank, a working fluid pump, and a sampling probe. The system provides a robust analysis system for a user to test vehicle emissions without being highly trained on the device, as the device is protected from misuse. A position sensitive sensor is used to ensure that the system is not damaged if the system is tipped over or placed in a position that would produce false results. Additional features include differential pressure sensors, a sealed and replaceable tamper resistant working fluid tank, a solvent recovery system, an anti-cheat device, and fluid purity sensors.

A droplet generator includes a chamber including an enclosed space filled with gas having vapor, a tube extending through the chamber, a gas flow channel inside the tube, and a heater in the chamber. The tube includes a sidewall having an outer surface exposed to the enclosed space of the chamber, and an inner surface. The tube contains liquid. The heater is operable to change a phase of the liquid contained in the tube to vapor such that the vapor is provided into the enclosed space. A pressure in the enclosed space is higher than a pressure in the gas flow channel such that the vapor in the enclosed space flows to the gas flow channel by passing through the tube.

Calibrated particle analysis apparatus and method are provided. In the calibrated particle analysis apparatus, a gas exchange device and several flow controllers are disposed in front of a particle analyzer. Therefore, when the calibrated particle analysis apparatus is used, gases of a sample can be exchanged with a carrier gas suggested to be used with the particle analyzer. Hence, the accuracy of analyzing the particles can be increased, and possible hazards from dangerous or toxic materials can be avoided.

A wick liquid sensor suitable for use in a particle condensation device is provided. The sensor includes a light source configured to illuminate a surface of the wick. A detector is configured to detect wick reflected light from the light source and determine the intensity of reflected light. The wick is formed from a porous media that is wettable by the liquid, and becomes translucent when filled with the liquid. The amount of reflectivity decreases as the saturation content of the liquid in the wick increases.

Provided herein is a particle analyzer that is operably connected to a probe unit that is capable of both dislodging particles from a surface and sampling the particles after they have been dislodged. The devices and methods described herein may be lightweight and/or handheld, for example, so that they may be used within a cleanroom environment to clean and sample permanent surfaces and tools. The devices may include optical particle counters that use scattered, obscured or emitted light to detect particles, including condensation particle counting systems or split detection optical particle counters to increase the sensitivity of the device and thereby facilitate detection of smaller particles, while avoiding the increased complexity typically required for the detection of nanoscale particles, such as particles less than 100 nm in effective diameter.

Various embodiments include methods and systems for reducing false-particle counts in a water-based condensation particle counter (CPC). One embodiment of a method includes delivering water into multiple wicks used for transporting separate portions of an aerosol sample flow, with the wicks extending from a wick stand on a first end to a flow joiner on a second end, combining particles from the separate portions of the aerosol sample flow into a single aerosol stream within the flow joiner prior to transporting the combined aerosol sample stream into a particle detection chamber within the CPC, sensing an excess volume of water delivered to the wicks, collecting the excess volume of water in a collection reservoir, and after receiving a signal corresponding to the excess volume of water, draining the excess volume of water from the collection reservoir. Other methods, systems, and apparatuses are disclosed.

Provided herein is a particle analyzer that is operably connected to a probe unit that is capable of both dislodging particles from a surface and sampling the particles after they have been dislodged. The devices and methods described herein may be lightweight and/or handheld, for example, so that they may be used within a cleanroom environment to clean and sample permanent surfaces and tools. The devices may include optical particle counters that use scattered, obscured or emitted light to detect particles, including condensation particle counting systems or split detection optical particle counters to increase the sensitivity of the device and thereby facilitate detection of smaller particles, while avoiding the increased complexity typically required for the detection of nanoscale particles, such as particles less than 100 nm in effective diameter.

Disclosed herein is a method comprising directing, from a distribution unit, a stream comprising at least one of solid CO.sub.2 particles or CO.sub.2 droplets toward an article, wherein the article comprises a plurality of surface particles, and wherein the stream comprising at least one of solid CO.sub.2 particles or CO.sub.2 droplets causes at least a portion of the plurality of surface particles on the article to dislodge from the surface of the article; collecting, on a surface of a substrate having a pre-determined initial state comprising initial surface particles on the surface of the substrate or a real-time aerosol sampling unit, at least some of the portion of the plurality of surface particles dislodged from the surface of the article; analyzing the surface of the substrate after performing the collecting; and determining at least one of a size, a morphology, a chemical composition, a particle number concentration, or a particle size distribution of the portion of the plurality of surface particles that were dislodged from the surface of the article and collected on the surface of the substrate.