The purpose of this paper is to assess technologies used in the monitoring of nano-particles that are available commercially and under research. The goal of the assessment is to propose a new device based on the technologies assessed. The assessment is performed based on information obtained from literatures review of articles and brochures, and from communications with representatives of the manufacturers of the counters. Two types of nano-particles counters were assessed; counters that are currently commercially available are the condensation particle counter (CPC), the scanning mobility particle spectrometer (SMPS). A description of how each counter works is given, and the advantages and disadvantages are highlighted. Experimental results showed that the performance of capillary had been installed and cleaned. The SMPS mean diameter fell within the range of the NIST standard. The sample offered well distribution in 300 and 400 nm.