A Coulter-style, microfluidic sensor formed by stacking a plurality of
substantially non-electrically conductive layers, typically formed from
thin polymer films. Certain layers carry patterned electrodes that are
arranged to permit their connection to an electrical interrogation
circuit. Electrodes may be disposed in a 3-dimensional array in the
sensor. A fluid path through the sensor includes an orifice sized to
promote single-file travel of particles. The orifice may be defined by
the entrance to a hole passing through at least one layer and at least
one electrode. Particles entrained in an electrolytic carrier fluid may
be detected, or otherwise characterized, by interrogation circuitry
connected to the sensor. Certain sensors may include portions of a fluid
path disposed parallel to the layers. In certain preferred embodiments,
the sensor is carried by a cartridge, which is adapted to couple with an
interrogation platform. Desirably, such coupling places the sensor
in-circuit with operable interrogation electronics, as well as with a
fluid-flow control device. Structure included in a cartridge may provide
fluid sample loading, routing, and storage capabilities.