Development of an integrated microfluidic electrostatic sampler for bioaerosol

Abstract Here, an integrated microfluidic electrostatic sampler (IMES) was designed and evaluated, consisting of a unipolar charging chamber, a half cylinder precipitation electrode and a collection chip for automated air sample delivery. The collection chip includes a half-open microchannel covered with a hydrophobic mesh and a peristaltic micropump. Airborne particles were first charged in the charging chamber and then precipitated into the half-open microchannel by the electrostatic field. After sampling, the integrated micropump automatically delivered the collection liquid through the half-open microchannel to the liquid outlet, washing away those deposited particles into collection reservoir. The maximum allowable velocity in the half-open microchannel was higher than 200 mm/s which is well above the normal operating speed of sample delivery, thus water transportation was quite stable in use. The collection efficiencies of airborne particles and bio-particles were investigated for the sampler. The tested maximum sampling flow rate was 13.2 L/min and the corresponding maximum effective collection efficiency was about 40% for particles smaller than 5 μm at charging voltage of −1.8 kV and collecting voltage of −7 kV. The preliminary experiments showed that the collection efficiencies of bio-particles were about 16% with aerosolized Bacillus subtilis . The lower collection efficiency of bio-particles was partially due to the particle loss on the hydrophobic mesh. Taking into consideration its compact size and integrated function of charging and automatic liquid sample delivery, the IMES is a bioaerosol sampling system ready for integration with subsequent automated detection equipment.