| Summary: | 碩士 === 國立中正大學 === 化學暨生物化學研究所 === 106 === Mico-centrifugal force driven by ionic wind through concentration of suspended particles is emerging micro-fluidic technique. When corona needle tip is applied with high AC voltage, the electrode makes the surrounding air polarized and charged. The charged ions accumulated at the needle tip reaching charge will repel from each and finally eject to produce ionic wind. When the corona needle is close to one hemispherical droplet sitting on flat glass slide, the ionic wind wiping across the liquid surface can induce micro-centrifugal vortex inside the droplet to drag suspended particles to the droplet bottom to trap at the stagnant point. Besides using this electrohydrodynamically generated ionic wind, the droplet evaporation can be enhanced because the eddy air streams around the droplet substantially increase the moisture removal rate. The liquid evaporation can induce internal fluid circulation to assemble particles on the surface. When the surface tension is significantly altered to stretch the contact line, the droplet is flatten as a liquid film to accelerate drying processes. The droplet is finally dried down. The trapped particles then become solid deposits to concentrate on the glass slide. This device combines with Raman microscope to detect SERS tags labeled with Salmonella in sample droplets. The results show that this method success in low concentration of detection for the Salmonella (1 × 103 -3 × 10 CFU/mL). The ionic wind device is a very simple, rapid, sensitive and high efficiency analytical method when used with SERS tags. This work provides a rapid detection platform for low concentrations of foodborne diseases.
Keyword: Ionic Wind、Salmonella、Gram Staining
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