How Thermal Mass Changes the Behavior of a PI Heater

https://precision-heating-elements.pinehavenscope.com/posts/mica-heater-design-considerations-for-efficient-heat-transfer

In sensors, a pi heater must deliver heat in a controlled way. It uses a thin resistive foil circuit laminated in polyimide film. One useful trait is fast response. Still, local hot spots can change the result