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Mobile Dust Monitor MDM-2

Mobile measuring instrument with scattered light sensor for real-time monitoring of PM2.5 concentrations

The compact and lightweight, hand-held measuring instrument MDM-2 (Mobile Dust Monitor) measures the current PM2.5 concentration at the measuring site in real time. It applies a photometric method using scattered light (nephelometry). A graphical trend indicator shows changes in the PM2.5 concentration.


Key Features

  • Real-time measurement of PM2.5 concentrations
  • Large color touchscreen
  • Graphical trend indicator
  • Several selectable measuring ranges
  • Interfaces: Mini-USB, Micro-SD, Bluetooth
  • Battery-powered (rechargeable via USB interface)



The MDM-2 consists of the following principal components:

  • Dispersion photometer with laser diode and photodetector
  • Color touchscreen for operating the device and displaying the measured values
  • Pump and intake port with insect screen (volumetric flow rate approx. 0.3 l/min)
  • Temperature and humidity sensors
  • Rechargeable battery
  • Mini-USB, Micro-SD, and Bluetooth interfaces

Operating principle

For measuring purposes, ambient air is drawn in through an intake port, protected by an insect screen, at a volumetric flow rate of approx. 0.3 l/min. For zero point adjustment purposes, a zero air filter is connected to the intake port. The adjustment is performed automatically.

The air that is to be measured enters the dispersion photometer through the intake port. Inside the instrument, the light emitted by a laser diode illuminates a measuring space defined by the optical path. The light reflected by the aerosol particles within this measuring space is captured by a photodetector positioned at an angle of 90°. The voltage signal generated by the detector and then amplified represents a direct measure of the aerosol particle concentration in the measuring space. Because of the selected wavelength, the PM2.5 fraction dominates the photodetector’s measuring signal, which allows the fraction to be measured directly.

The measured PM2.5 concentration is displayed on the touchscreen in real time. In addition, the sequence of measured values is stored by the device and displayed as a behavior curve. Several measuring ranges can be selected for displaying the measured values. The default measuring range setting is 0 to 100 µg/m³.

The MDM-2 can be operated either as a standalone device or in conjunction with a Windows PC. Software is provided that enables the user to call device functions from the PC, save the measured values and plot graphs indicating trends.


The information on this website represents the state of knowledge at the time of writing. Technical specifications are subject to modifications. Comde-Derenda GmbH accepts no liability whatsoever for the content provided or for damages resulting from the use of its products.

Technical Data

Volumetric flow rate
approx. 0.3 l/min
Measurement duration
Measurement range 1
0 … 100 μg/m³
Measurement range 2
0 … 1000 μg/m³
Resolution 1 μg/m³
Response time
< 5 s
Measurement uncertainty (daily mean value) < 15 %
Power source
5 V DC
Power requirement
approx. 0.8 VA
Interfaces Mini-USB, Micro-SD, Bluetooth
Dimensions Length 220 mm
Width 90 mm
Height 75 mm
Weight approx. 485 g

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