  We describe the fabrication and characterization of solid 3-dimensional
electrodes in direct contact with microfluidic channels, implemented using a
single photolithography step, allowing operation in high-dielectric constant
media. Incorporation and self-alignment of electrodes is achieved by combining
microsolidic approaches with exploitation of the surface tension of low melting
point alloys. Thus the metal forms the walls flanking the channel. We show that
this approach yields electrodes with a well-defined, reproducible morphology
and stable electronic properties when in contact with biochemical buffers. By
combining calibration of the electric field with free-flow electrophoresis we
quantify the net solvated charges of small molecules.
