A scalable monolithic sensor assembly, controller, and methods of making and installing same are disclosed. The sensor assembly includes a sensor head sized to fully traverse the diameter of the pipe such that its electrodes sample a voltage indicative of the entire pipe flow across its diameter. An improved stem design is included that decreases insertion force and increases lateral stability of the sensor head. An improved insertion device is disclosed that provide for independent axial insertion and rotation. An improved core is disclosed that minimizes interference of magnetic fields and reduces manufacturing costs. An improved controller is disclosed that improves sensitivity.