An Air Sampler With Particle Filter Using Innovative Quad-Inlet Cyclone Separator and High Voltage Trap

The air sampler collects all the floating particles in the air, and the samples can be analyzed by a nondispersive thermopile device. These particles are different in size and it is necessary to retain only the size range of the interesting objects in the sampler. With the interest of sampling the Fusarium spores, which have particle diameter range of around 10μm to 70μm, and eliminating particles smaller than 10μm and particles larger than 70μm, in this paper, a novel method of combining a quad-inlet cyclone separator and a high voltage trap is proposed. At a small size, such cyclone separator is a new design having four inlets to facilitate the cyclone to intake the particles from any direction. The quad-inlet cyclone separator filters away the large size particles (low pass). By applying di-electrophoretic force in the high voltage portion, the trap can eliminate the small size particles (high pass). The combination of these two devices creates a system, which works as a particle bandpass filter. To investigate the features as well as to study the appropriate parameters of the cyclone and the trap, the numerical simulations for the trap work have been performed by COMSOL Multiphysics. In the simulations, wheat, turmeric, and Fusarium spore objects were investigated. From the simulation, the bandpass ranges of the wheat, turmeric and Fusarium samples are [19.5μm-75μm], [14.5μm-52.5μm] and [15.5μm-67μm], respectively. The experimental results have consolidated that the device can reduce significantly and automatically the presence of small size particles, and especially filter well the particles which have a size larger than 70μm. In addition, with the homogeneous electric field in the high voltage trap, the sample distribution on the electrodes was fairly smooth which is useful in later quantifying Fusarium spores by the thermopile device. By using a strong vacuum pump, the internal air sample could be cleaned easily, so the device is reusable. The designed particle band pass filter is essential for our Fusarium detection device and it can be widely applied in the other air sampling and analysis applications.