Micro Air Borne Particulate Analyzer (MicroAPA)

摘要

This report describes the design, development, fabrication and testing for primary functionality of an integrated prototype of a small footprint particle size sampler, the MicroAPA. The new instrument consists of a custom designed and fabricated MEMS based ionizer and mini-DMA (separator electrodes), custom designed electrometer and Faraday's cup, as well as off-the-shelf components. The MEMS based corona ionizer and mini-DMA were constructed using microfabrication techniques. This allows a corona pin diameter of 20um to be easily achieved at a very low cost. It also permits the corona pin to be accurately positioned between two miniature copper grids 4mm apart. By using a high voltage but low current power source, a steady corona discharge is achieved at very low power consumption (less than 20mW). In-lab experiments show that the MEMS based corona ionizer .and mini- DMA are able to adequately sort particles ranging from 30nm to 300nm (with the size distribution limited by the TSI constant output atomizer capabilities, which is 30nm to 300nm).