1 November 2003

Saline, MI-based Sensors, Inc. announced the introduction of new particulate matter (PM) measurement instruments: the SEMTECH QCM (quartz crystal microbalance) and MPS (micro-proportional sampler). These instruments are intended for the quantification of PM mass emissions from internal combustion engines, including transient operating conditions, in the laboratory, as well as in portable applications.

Sensors has acquired worldwide manufacturing and distribution rights to QCM and MPS from their designer, Booker Systems, Ltd. of Lytham, Lancashire, England.

The SEMTECH QCM utilizes electrostatic precipitation to collect aerosol particles from a known volume of air and to deposit them on an oscillating piezoelectric crystal. The natural oscillation frequency of the crystal—approximately 5 MHz—is reduced in proportion to the amount of material deposited on its surface. By measuring these shifts in frequency, the SEMTECH QCM can calculate the mass of the particulate matter with a resolution approaching one nanogram. The high QCM frequency was also selected to avoid errors from shock and vibration.

According to Sensors, the instrument offers fast response with the ability to provide transient PM mass measurements. Its small size and light weight allow for portable applications.

To complement the QCM, the MPS was developed to permit transient, in-use measurements, where the use of a constant volume sampling (CVS) system would be impractical. The SEMTECH MPS delivers fast response times of 0.1 s and operational speeds greater than 5 Hz. In addition, the unit is small enough to be easily transportable, and, as a 12 VDC system, is practical for field use.

Software for the SEMTECH QCM and MPS is based on the Labview platform, which allows the instruments to be configured for specific measurement requirements.

Source: Sensors