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DISCmini: world’s smallest handheld nanoparticle counter

DISCmini: a handheld diffusion size classifier for nanoparticle measurement Courtesy: Testo

They’/re claiming this is the world’s smallest in a July 12, 2017 news item on Nanowerk,

Testo, Inc., the world’s leading manufacturer of test and measurement instruments, announces the DiSCmini, the smallest handheld instrument for the measurement of nanoparticle. DiSCmini measures: particle number, average particle diameter and lung-deposited surface area (LDSA) with time resolution and logging at 1 second (1 Hz).

Testo’s DISCmini product page offers a video and more details,

Negative health effects due to nanoparticles appear to correlate particularly well with number concentration or surface. Epidemiological and toxicological studies are still mainly based on total mass, or they use fuzzy proxies like “distance from a busy road” to describe personal exposure, although the health-related effects of particle number concentration are well known. We believe that this contradictory situation is due to the lack of adequate sensors on the market.

This gap is now closed with Testo Particle´s handheld version of the “Diffusion Size Classifier”, testo DiSCmini.  The testo DiSCmini is a portable sensor for the measurement of particle number and average diameter with a time resolution of up to 1 second (1 Hz). The simultaneous capture of number concentration and particle size allows the specification of other characteristic parameters, such as the particles surface (Lung Deposited Surface Area, LDSA). The instrument is battery powered with a lifetime of up to 8 hours; data can be recorded on a memory card, and transferred to a external computer via USB cable.

The testo DiSCmini is particularly efficient for personal exposure monitoring in particle-loaded work space with toxic air contaminants such as diesel soot, welding fumes, or industrial nanomaterials.

The testo DiSCmini is based on the electrical charging of the aerosols. Positive air ions generated in a corona discharge are mixed with the aerosol. The charged particles are then detected in two stages by electrometers. The first detector stage is a pile of steel grids; small particles will preferably deposit on it by diffusion. The second stage is a high-efficiency particle filter which captures all the other particles. The mean particle size can be obtained by analysis of the two currents measured on the stages. The particle count is determined with the total current. The testo DiSCmini detects particles ranging in size from 10 to about 700 nm, while the modal value should lie below 300 nm. The concentration range is from about 1’000 to over 1’000’000 particles per cubic centimetre. The accuracy of the measurement depends on the shape of the particle size distribution and number concentration, and is usually around 15-20% compared to a reference CPC. The unit should be serviced and calibrated once a year.

Unlike other instruments the testo DiSCmini needs neither working liquid of any kind nor radioactive sources. Therefore, it can be operated in any position and over extended periods without requiring a liquid refill. Typical applications include the determination of personal exposure in particle-loaded jobs (diesel soot, welding fumes, industrial nanomaterials) or in vulnerable groups (asthmatics, COPD patients). The development of large area survey grids of ambient air is becoming possible. The small size of  the testo DiSCmini makes the instrument particularly suitable for personal carry-on measurement campaigns. The high measurement frequency of 1 Hz allows the instrument to monitor rapid changes in the aerosol. This feature is particularly interesting to local or defined sources of particle generation. The equipment is designed for situations and applications where quick and easy access to particle number concentration and average diameter is desired.

For anyone interested in the technical specifications, there’s the DISCmini product brochure.