Ellenállásváltozás

Ellenállásváltozás refers to the phenomenon where the electrical resistance of a material changes due to external stimuli. This change in resistance can be utilized in various sensor applications.

One common type of resistance change is observed in thermistors, where the resistance varies significantly with temperature. NTC (Negative Temperature Coefficient) thermistors decrease in resistance as temperature increases, while PTC (Positive Temperature Coefficient) thermistors exhibit the opposite behavior. These are widely used for temperature sensing and control.

Another form is magnetoresistance, where the resistance changes in the presence of a magnetic field. Giant Magnetoresistance (GMR) and Tunnel Magnetoresistance (TMR) are particularly significant effects that have enabled the development of high-density hard disk drives and magnetic sensors.

Photoconductivity is another example, where the resistance of a material decreases when exposed to light. This principle is the basis for photoresistors (or light-dependent resistors, LDRs), which are used in automatic lighting systems, light meters, and optical switches.

Piezoresistance is the change in electrical resistance of a material when mechanical stress is applied. This effect is crucial in strain gauges and pressure sensors, allowing for the measurement of deformation and force.

Finally, chemiresistors exhibit a change in resistance upon exposure to specific chemical substances. This property is explored for gas sensors and chemical detection systems, where the interaction of the analyte with the sensitive material alters its conductivity. The understanding and application of ellenállásváltozás are fundamental to many areas of modern technology.