Sensitive resistor

Sensitive resistor refers to a resistor whose device characteristics are sensitive to temperature, voltage, humidity, light, gas, magnetic field, pressure, and other effects. The symbol for sensitive resistance is to add a diagonal line to the symbol for ordinary resistance and mark the type of sensitive resistance next to it, such as t V, etc.
1. Varistor
There are mainly silicon carbide and zinc oxide varistors, with zinc oxide having more excellent characteristics.
2. Humidity sensitive resistor
Composed of a humidity sensing layer, electrode, and insulator, humidity sensitive resistors mainly include lithium chloride humidity sensitive resistors, carbon humidity sensitive resistors, and oxide humidity sensitive resistors. Lithium chloride humidity sensitive resistor decreases with increasing humidity, but its disadvantages include small testing range, poor repeatability of characteristics, and significant temperature influence. The disadvantages of carbon humidity sensitive resistors are low sensitivity at low temperatures, high resistance value influenced by temperature, and less use due to aging characteristics. The performance of oxide humidity sensitive resistors is superior and can be used for a long time. The temperature effect is small, and the resistance value is linearly related to humidity changes. There are materials such as tin oxide, nickel ferrite, etc.
3. Photosensitive resistor
A photosensitive resistor is an electronic component whose conductivity changes with the force of light. When a substance is illuminated, the concentration of charge carriers increases, thereby increasing the conductivity, which is known as the photoconductivity effect.
4. Gas sensitive resistor
It is made by using certain semiconductors to absorb a certain gas and undergo oxidation-reduction reaction. The main components are metal oxides, and the main varieties include metal oxide gas sensitive resistors, composite oxide gas sensitive resistors, ceramic gas sensitive resistors, etc.
5. Force sensitive resistor
Force sensitive resistor is a type of resistor whose resistance changes with pressure, and is called a piezoelectric resistor abroad. The so-called pressure resistance effect refers to the effect that the resistivity of semiconductor materials changes with mechanical stress. It can be made into various torque meters, semiconductor microphones, pressure sensors, etc. The main varieties include silicon varistors and selenium tellurium alloy varistors. Relatively speaking, alloy resistors have higher sensitivity.
6. Thermistor
Thermistors are a type of sensitive components, and their resistance values exhibit a step change with the temperature of the thermistor body, exhibiting semiconductor characteristics.
Thermistors are divided into positive temperature coefficient thermistors (PTC thermistors) and negative temperature coefficient thermistors (NTC thermistors) based on their temperature coefficients.