A fluid immersion control system may use a common electrode along with a plurality of sensor electrodes at a planar surface associated with a distal end of an immersion microscope objective to monitor electrical resistance of a fluid as an indication of presence of a fluid layer having a meniscus greater than a diameter of an optical axis used for immersion microscopy. The fluid immersion control system may activate replenishment of the fluid when the resistance indicates that the diameter is not immersed in the fluid.