QTC™ Material Technology
Pressure sensitive control and electrical switching
Pressure-sensing and Switching
The potential for the QTC™ Material to transition from an insulator to a conductor (i.e. change its electrical property) is influenced by how much deformation the material is experiencing as a result of the applied mechanical pressure.
QTC™ Material can be used to produce low profile, low cost, pressure activated switches or sensors that display variable resistance with applied force and return to a quiescent state when the force is removed. The difference between a QTC™ Material switch and a QTC™ Material sensor is arguably only the speed and amount of physical input required to achieve the required switching point or resistance range.
Open circuit: Rest state > QTC™ Material insulating. In unstressed state, QTC™ Material behaves as an insulator (R>1012 Ω).
Closed circuit: Compressed state > QTC™ Material conducting. Under compression, tension or torsion the resistance drops gradually and controllably. QTC™ Material can be capable of passing high currents.
Force (N) and Resistance (Ω). The graph shows the effect of varying the current at constant voltage.
The transition from insulator to conductor follows a smooth and repeatable curve, with the resistance dropping exponentially.
In theory, the resistance of QTC™ Material decreases exponentially with compression – subsequently, allowing increasing current flow through the material. In practice uniform compression is rarely achieved and therefore the resistance change with compression will deviate from a true exponential.