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RTI - MicroPEM

General Description

The MicroPEM, developed by RTI International, is a portable sensing device that measures particles smaller than 2.5 micrometers. 

Principle of Operation

The MicroPEM operation combines real-time nephelometry and integrated referee filter particulate matter measurements operating in parallel. The device carries an impactor and a light scattering particle detector. The impactor consists of a nozzle and an impaction plate. When an aerosol stream passes through the nozzle and impinges upon the plate, particles with large enough inertia will impact upon the plate while smaller particles will pass as an aerosol to the next stage. A built-in optical bench contains a supporting circuit, a laser and a highly sensitive photodiode. Particles get shifted through the impactor and then enter the testing chamber. When particles pass through the laser beam, the scattered light will be sensed by the photodiode and the light intensity change is transferred into a voltage change. The supporting circuit will amplify the electrical signal and further process it. The air flowrate through the system is 500mL/min. 


  • Dimensions: N/A
  • Weight: <240 g
  • Battery: Yes (3 AA-cell alkaline or lithium batteries provide up to 40 hrs of continuous operation)
  • Power supply: Yes (120 VAC/60Hz AC adapter to USB)
  • Sensor lifetime: N/A
  • Clock function: Yes (Requires 2032 coin cell battery)
  • Sampling mechanism: Pump
  • Environmental operating conditions: N/A
  • Internal data logging: Yes (32MB)
  • PC data logging: No
  • Communications: USB to mini-usb cable
  • Weatherproof: No


  • Ambient air monitoring
  • Indoor Air Quality
  • Personal exposure monitoring

Manufacturer's product webpage

    South Coast Air Quality Management District

    21865 Copley Dr, Diamond Bar, CA 91765



    © 2024 South Coast Air Quality Management District