Have you ever left your smartphone in the car during hot weather? If that's the case, your screen may already display an image of the thermometer and a warning of phone overheating. That's because there is a miniature embedded temperature sensor that can measure the internal temperature of the phone. Once the internal temperature of the phone reaches a specific level (for example, if the iPhone is turned off near 113 degrees Fahrenheit), the temperature sensor will send an electronic signal to the embedded computer. Conversely, this will restrict users from accessing any application or feature until the phone cools down, as running the program will only further damage the internal components of the phone.
A temperature sensor is an electronic device that can measure its ambient temperature and convert input data into electronic data to record, monitor, or emit signals of temperature changes. There are many different types of temperature sensors. Some temperature sensors require direct contact with the monitored physical object (contact temperature sensor), while others indirectly measure the temperature of the object (non-contact temperature sensor).
Non contact temperature sensors are typically infrared (IR) sensors. They remotely detect the infrared energy emitted by objects and send the signal to the calibration electronic circuit that determines the temperature of the object.
Contact temperature sensors include thermocouples and thermistors. A thermocouple is composed of two conductors, each made of a different type of metal and connected together at one end to form a junction. When the junction is exposed to heat, a voltage directly corresponding to the temperature input is generated. This occurs due to a phenomenon called thermoelectric effect. Thermocouples are usually cheaper because of their simple design and materials. Another type of contact temperature sensor is called a thermistor. In thermistors, the resistance decreases with increasing temperature. There are two main types of thermistors: negative temperature coefficient (NTC) and positive temperature coefficient (PTC). Thermistors are more accurate than thermocouples (capable of measuring between 0.05 and 1.5 degrees Celsius), and they are made of ceramics or polymers. A resistance temperature detector (RTD) is essentially a metal counterpart of a thermistor and is the most accurate and expensive temperature sensor.
Temperature sensors are used in automobiles, medical equipment, aerospace and military industries, the Internet of Things, and other types of machinery.
