Temperature sensor principle is a thermostat, bimetal thermostat, thermistor; applications are refrigerators, household appliances, medical instruments and equipment.
Principle of temperature sensors
1, thermostat
Thermostat is a contact temperature sensor, consisting of a bimetallic strip of two different metals (e.g. aluminum, copper, nickel or tungsten). The difference in the coefficients of linear expansion of the two metals results in a mechanical bending motion when they are heated.
2. Bimetallic Thermostat
The thermostat consists of two metals with different heat levels glued together back to back. When it is cold, the contacts close and current passes through the thermostat. When it gets hot, one metal expands more than the other, and the bonded bimetallic strip bends upward (or downward), opening the contacts and preventing current flow.
3. Thermistors
Thermistors are usually made of ceramic materials, such as nickel, manganese or cobalt oxides plated in glass, which makes them easy to damage. Their main advantage over the fast-acting types is how quickly they respond to any changes in temperature, accuracy and repeatability.
Most thermistors have a negative temperature coefficient (NTC), which means that their resistance decreases with increasing temperature. However, there are some thermistors that have a positive temperature coefficient (PTC) and their resistance increases as the temperature rises.
Temperature sensor applications
1, refrigerator
When the temperature inside the refrigerator is higher than the set value, the refrigeration system starts automatically; and when the temperature is lower than the set value, the refrigeration system stops automatically. The control of the refrigerator temperature is realized by the temperature sensor.
2, household appliances
Temperature sensors are widely used in household appliances (microwave ovens, air conditioners, hoods, hair dryers, toasters, induction cookers, frying pans, warming fans refrigerators, freezers, water heaters, water fountains, dishwashers, disinfection cabinets, washing machines, drying machines, as well as low and medium-temperature drying box, thermostat boxes, temperature measurement and control, etc.). (Measurement and control, etc.).
Medical/home thermometers, portable non-contact infrared temperature thermometers and many more.
3, medical instruments and equipment
Medical application of a variety of sensors on the human body temperature, blood pressure and intracavitary pressure, blood and respiratory flow, heart and brain waves, pulse and heart sound, etc., high accuracy detection, timely feedback of the results of the treatment, the realization of the patient's automatic detection and monitoring.