Medical Definition of adhesive. 1: an adhesive substance; especially : a substance (as glue, starch, paste, or mucilage) that bonds two materials together by adhering to the surface of each.
The sensors physically measure the tire pressure in each tire and report it to the vehicle's instrument cluster or a corresponding monitor. Some units also measure and alert temperatures of the tire as well. These systems can identify under-inflation in any combination, be it one tire or all, simultaneously.
Added to this mix is the often-proprietary technology used by each manufacturer, making the range of sensors out there a confusing mix for shops and consumers. Indirect tire pressure monitoring systems don't rely on sensors to do the work, or at least not pressure sensors.