Journal: Scientific Reports

Article Title: Electrokinetically driven continuous-flow enrichment of colloidal particles by Joule heating induced temperature gradient focusing in a convergent-divergent microfluidic structure

doi: 10.1038/s41598-017-11473-w

Figure Lengend Snippet: Schematic of the entire experimental setup. A PDMS microfluidic channel with a convergent-divergent structure is loaded with fluorescent particles dispersed in a buffer solution, and is placed on the microscope objective stage. Two platinum electrodes placed in each reservoir of the microchannel are for supplying the required voltages provided by a function generator together with an amplifier. The electrically produced Joule heat in the solution couples with the convergent-divergent structure to give rise to significant axial temperature gradient near the narrowest constriction of channel, as is evident from the inset showing the axial temperature profile. During the experiments, the mercury lamp illuminates the fluorescent particles, and the recording of particle enrichment is through an objective lens and a CCD camera. The bottom-left portion presents a schematic of particle enrichment due to four particle transport mechanisms, including the advection of particle due to electroosmotic flow of buffer solution (u), electrophoresis of particle (u ep ), dielectrophoresis of particle (u dep ) and thermophoresis of particle (u tp ).

Article Snippet: The enriching phenomena were monitored through a 5x objective lens and then recorded with a CCD camera (Sensovation AG, Germany) at a rate of 15 frames per second.

Techniques: Microscopy, Produced, Electrophoresis