Development of an Electrostatic Precipitation Based Automated Bioaerosol Sensing System

Miaomiao Tan, Maosheng Yao* and Tong Zhu*

State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China

     Abstract Number: 409
     Last modified: May 12, 2010

Abstract
There is an increased interest in realtime detection of biological aerosols. However, such task often requires an efficient aerosol-to-hydrosol system that can be integrated with other sensing techniques. To achieve such objective, an automated bioaerosol collection and output system was developed using a new electrostatic sampling method and a peristaltic pump in this study. The electrostatic sampler was designed using a half-ball shape steel electrode (radius is 45 mm) with three aerosol inlets on the top and a circular copper plate electrode (6 and 16 mm in diameter) suited inside a circular plastic support. Above the plate electrode, a plastic cylindrical reservoir (14mm in diameter and 1 mm in height) was built with one inlet and one outlet made of copper(2 mm in diameter). These outlets are connected to the peristaltic pump for liquid delivery. Next to the reservoir, there are two aerosol outlets connected to a vacuum pump. When operated, the electrodes of the system were connected to a high voltage supply, and the aerosol samples were precipitated by the electrical force into the reservoir. The collection efficiencies of the system were tested when collecting indoor virus size particles using an optical particle counter under different experimental conditions.

Experimental data showed that the system could collect more than 80% of indoor 0.3-0.45 um particles at a low sampling flow rate of 1.2 L/min when a 20 kV voltage and a particle charger (1.5 V) were applied. The collection efficiency decreased to below 20% when the voltage decreased to 6 kV. Increasing sampling flow rate was observed to lead to the decrease of the collection efficiency down to 10% at 16 L/min. When a particle charger was applied, use of larger plate electrode (16 mm in diameter) was shown to significantly improve the collection efficiency up to 2 times than that of 6 mm. When operated for sampling indoor air, the system obtained a culturable bacterial concentration of 200/m3 at 2 L/min and 50/m3 at 5 L/min. In this study, the collected air samples including aerosolized H3N2 virus in the reservoir were successfully transported onto a sensor device at 0.5 ml/min through a peristaltic pump, while the fresh distilled water was also continuously delivered into the reservoir at the same flow rate. The developed system presents an electrostatic sampling based platform for automated bioaerosol sensing when coupled with other available biosensors.