Sensors for thermal interface switches precisely detect media boundaries based on thermal conductivity variations. Typically comprising heated elements immersed directly into process media, these sensors rapidly detect interface changes as thermal conductivity shifts. Built from corrosion-resistant materials, they withstand harsh process environments, including high temperatures, pressures, and abrasive or chemically aggressive media. Highly sensitive and accurate, these sensors reliably differentiate interfaces between liquids, gases, and solids, supporting critical control actions, alarms, and safety protocols across refining, chemical processing, and wastewater management industries.