A fluid pump (100) having a homopolar motor (110). The homopolar motor includes a rotatable disk (115) defining at least one impeller (120). The impeller can include an orifice within the rotatable disk. The rotatable disk can be at least partially disposed within a cavity (145) defined in the substrate (105), such as a ceramic substrate, a liquid crystal polymer substrate, or a semiconductor substrate. A closed loop control circuit (335) can be included to control the rotational speed of the rotatable disk. For example, the control circuit can control a voltage source or a current source that applies voltage across the rotatable disk. The control circuit also can control a strength of a magnet (310) that applies a magnetic field (305) substantially aligned with an axis or rotation (155) of the rotatable disk.