Electrical Control of Debye Screening in Liquid Microchannels for Ionic Separations

摘要

In this work we demonstrate controlled electrostatic depletion and accumulation of liquid ions in microscale channels by applying voltage across a dielectric coating on the channel walls. A 100μM fluorescent ionic dye (FITC) was flown through a series of oxidized (SiO{sub}2) Si microscale channels (each 10μm wide, 15μm deep and 1cm long). Negative and positive voltages on the Si substrate were used to deplete and accumulate the negative fluorescent FITC{sup}(2-) ions, respectively. Theoretically calculated plots were used confirm the experimental results. This ability to screen ionic species based on charge can now be applied towards creating a platform for multidimensional separations (charge, surface energy, size) in a single lab-on-chip format.