Device Structure Design And Principle Analysis For Collecting PM2.5 And PM2.5-10 In Air

Actuators rely on the piezoelectric effect of piezoelectric materials to achieve mutual conversion between power and mechanical energy is called piezoelectric transducer. Piezoelectric transducers are the primary elements in ultrasonic technology, which have great varieties, extensive application. And they will have broad application prospects in the micro/nano field to manipulate micro/nano-scale objects. This project researches on the principles and characteristics of the fine particulate matter’s collection driven by piezoelectric transducer and the reflector. The following are the primary content:Giving a brief introduction to the collection of PM2.5 and PM2.5-10 in air as well as the harm it brings to. We provide some existing methods of collecting particulate matter in air including high-efficiency particulate air(HEPA) filtering, electrostatic precipitating and dielectrophoresis technology. These existing methods have their own advantages and disadvantages. To overcome these disadvantages of existing methods, we are going to demonstrate a novel strategy of collecting coarse and fine droplets from the air.Based on previous research on the ultrasonic transducers of our research group, we carried out an experiment using the ultrasonic transducer and found that there are two types of deposit patterns, depending on the air gap thickness. One is that droplets collected onto the reflector’s surface form a series of concentric rings. The inner rings are more regular and have clearer boundaries than the outer rings. The other is that the deposit patterns are not regular and contains a mixture of spots and concentric rings. The radiation surface works in a flexural vibration mode at 56.9 k Hz, and the collection effects are related to the working frequency, working voltage, the thickness between the radiation surface and the reflector, working mode and working time.We use COMSOL Multiphysics(a kind of finite element analysis software) to calculate the acoustic radiation force and the acoustic streaming between the radiation surface and the reflector. When calculation results compared with the experimental phenomena, we found that the acoustic streaming is responsible for the formation of the series of concentric rings and the acoustic radiation force contributes to the formation of the mixture of spots.