Molecular detection in a microfluidic device by streaming current measurements

Using streaming current measurements, we demonstrate molecular detection in a microfluidic device. The streaming cut-rent varies depending on the channel surface conditions. For example, when highly charged polymers such as deoxyribonucleic acid (DNA) adsorb onto an oppositely charged surface, excess adsorption changes the total surface charge from positive to negative. We have shown that the measurement of the inversed or reduced streaming current is useful for the detection of charged and noncharged molecular adsorption in micro- and sub-microchannels.