A sensor includes a single capacitor that operates in two different modes to obtain capacitance and conductance information when a mixture flows between the electrodes of the capacitor. The system can include a fluid conduit that includes an inner wall structure and a pipe sleeve disposed along the inner wall structure to reduce the cross-sectional area of the interior of the conduit. The bobbin is combined with the covering member, and includes a bobbin body and a channel. Matched entity is integrated into the rule.