Design and evaluation of the field-deployable electrostatic precipitator with superhydrophobic surface (Fdepss) with high concentration rate

Here we report on further development of an electrostatics-based bioaerosol collector with high concentration rate. We developed a field-deployable version of the electrostatic precipitator with superhydrophobic surface (FDEPSS), which consists of two combined half-cylinder collection chambers and an integrated control box. The collector is made of a static dissipative material and each collection chamber features a 3.2 mm wide collection electrode. The round top part of each chamber contains eight carbon fiber ionizers arranged in two lines of four. The collected particles are removed by a 20 μL rolling water droplet. Sampler’s components were integrated into a control box. The FDEPSS was tested with two bacterial species, Bacillus atropheus and Pseudomonas fluorescens bacteria, and one fungal spore, Penicillium chrysogenum for 10 and 60 min collection times and showed collection efficiency of ~70% at a sampling flow rate of 20 L min^–1. The use of a collecting water droplet of 20 μL per collection chamber achieved sample concentration rates approaching 0.5 × 10⁶ min–1. The FDEPSS was also tested against BioSampler (SKC Inc., Eighty Four, PA) and Button aerosol sampler (SKC Inc.) when sampling bioaerosols outdoors for 60 min. The samples were characterized based on the total airborne adenosine triphosphate (ATP) concentration, which was reported as relative luminescence units (RLU). The FDEPSS detected 5.1 × 10⁵ RLU m^–3, while the BioSampler and the Button sampler showed 4.1 × 10⁵ RLU m^–3 and 8.7 × 10⁵ RLU m^–3, respectively. Since ATP analysis can be performed with small sample volumes, and the FDEPSS captures particles into 20 μL of liquid, resulting in a high concentration rate, we show that this sampler can detect the presence of airborne microorganisms 40× faster than the BioSampler or Button aerosol sampler. This FDEPSS feature could be integrated into bioaerosol detection systems, especially where concentrations are low and time is critical.