Aspects of the present disclosure are directed to the flow of analytes, particles or other materials. As consistent with one or more embodiments described herein, an apparatus includes a membrane having one or more pores in a membrane. First and second electrodes facilitate electrophoretic flow of analytes through the pore, and a third electrode controls movement of the particles in the pore by modulating the shape of an electric double layer adjacent sidewalls of pore. This modulation controls the strength of an electroosmotic field that opposes the electrophoretic flow of the analytes via the pore.