  Isoelectronic differential force measurements provide a unique opportunity to
probe controversial features of the thermal Casimir effect, that are still much
debated in the current literature. Isolectronic setups offer two major
advantages over conventional Casimir setups. On one hand they are immune from
electrostatic forces caused by potential patches on the plates surfaces, that
plague present Casimir experiments especially for separations in the micron
range. On the other hand they can strongly enhance the discrepancy between
alternative theoretical models that have been proposed to estimate the thermal
Casimir force for metallic and magnetic surfaces. Thanks to these two features,
isoelectronic differential experiments should allow to establish conclusively
which among these models correctly describes the thermal Casimir force.
