Temperature Sensors

• Thermistors use internal electrodes that sense surrounding heat and measure it through electrical impulses. They also help to control heat to some extent, usually causing the device to which they are attached to heat up much more slowly than it normally would. They are made with semi-conductor materials using temperature-sensitive resistance. There are two kinds of thermistors: NTC (Negative Thermal Coefficient) and PTC (Positive Thermal Coefficient). With the former, the resistance of the thermistor decreases as the temperature increases, and with the latter, the resistance increases as the temperature rises.
  
  

Large Resistance, Small Temperature Change

• There are several layers of tiny electrodes within the body of the thermistor, all of which are connected by semi-conducting materials. These materials offer resistance to the electricity being run through the thermistor, thereby causing it to register the heat from the electricity. Thermistors show a large resistance for a small temperature change, and most of them are made from manganese, cobalt, nickel and copper oxides. Silicon and germanium are also used in the production of thermistors.
  
  

Power Surges

• Thermistors are used to protect electronic circuits from power surges that usually take place when a "cold" device starts up and gradually warms. There is invariably a strong electrical input at the time the device is first activated, which can create an overload in the electronic components of the device. Thermistors reduce and control this surge and restrict it by gradually increasing the electrical input, rather than allowing it to happen all at once.