Abstract
Sample pre-concentration is an important step in many high-performance separation techniques, such as liquid chromatography or capillary electophoresis, which determines the detection sensitivity of separated samples. However, they either need particular microdevices or special surface treatment in local area, posing system fabrication/operation complexity. In this study, we employ simple and rapid surface plasma processes to create an asymmetry electroosmotic flow (EOF) in micro/nano channels. By this way, the sample can be concentrated into one side of the channel induced by the non-uniform zeta potential variation. We demonstrate that the concentrating ability for neurotransmitter (1μM Dopamine) in the modified asymmetry surface treated channel (500nm and 30 μ m channel depth) are 8.5 or 2.8 times larger than that in the channels with symmetrical surface treatment, respectively.