Electrostatic capture of airborne nanoparticles in swirling flows for bio-MEMS applications

Motivated by capture and detection of airborne biological agents in real time, we present the electrostatic capture of 100nm diameter polystyrene nanoparticles as a model system under swirling gas flows in a homemade particle collector having the forward outlet. The particle collector has five small positive electrodes on the bottom and one large grounded electrode on the top. The particles coming into the collector are slowed down during their swirling and stay in the collector before leaving. Particles captured on the center electrode of this collector were much less than those on the surrounding four electrodes and 10 - 25% of the particles with negative charges entering this collector were captured on the bottom electrodes at a flow rate of 1.1 l/min and an applied potential of 2 kV. Using a commercial CFD code FLUENT, we simulated the effects of the different types of collector outlet configurations and flow rates on the particles' trajectories, velocities, and travel times inside the collector. We also present the highest particle capture position inside the collector in those different configurations. The forward outlet configuration is the most favorable to particle capture among the tested configurations in terms of particles' minimum achievable velocities and their travel times at a flow rate of 1.1 l/min. This collector is well adaptable to integration with micro resonator devices and can be used for real-time monitoring of bioaerosols.