Counting system detects subnanometre particles

Edited by the Engineeringtalk editorial team Sep 2, 2005

A novel particle counting system that detects particles down to 1nm or even less has been introduced by Grimm Aerosol Technik, Ainring, Germany.

A novel particle counting system that detects particles down to 1nm or even less has been introduced by Grimm Aerosol Technik, Ainring, Germany.

Based on the principle of the Faraday cup electrometer, the Grimm FCE works by detecting the charge on the particles rather than relying on "growing" the particles to a detectable size as occurs with conventional nuclear condensation counters.

This extends the size detection range to below 1nm and has the additional benefits of a much faster response (50ms) and a working concentration range of four or five orders of magnitude.

It also eliminates the need for the condensation liquid used in traditional counters, usually butanol.

Very sensitive electrometers of this type are normally prone to noise and drift, but the Grimm FCE employs lock-in amplifier technology to overcome this problem.

Used with the Grimm "Vienna" electrostatic classifier, the Grimm FCE enables the study of sub-nano particles like protein molecules, viruses and even metal ions.

Important applications in the environmental field include the study of nucleation processes occurring in atmospheric photochemical reactions, and the "drive-by" measurement of automotive exhaust emissions.