Differences between thermopiles and conventional thermistors and thermocouples

Thermistors are a class of sensitive components that are divided into positive temperature coefficient thermistors (PTC) and negative temperature coefficient thermistors (NTC) according to their temperature coefficient.

Thermistors are typically characterized by temperature sensitivity and exhibit different resistance values at different temperatures. Positive temperature coefficient thermistors (PTC) have a higher resistance value at higher temperatures, and negative temperature coefficient thermistors (NTC) have a lower resistance value at higher temperatures, and they are both semiconductor devices.

Thermocouple is a commonly used temperature measuring element in temperature measuring instruments, which directly measures the temperature and converts the temperature signal into a thermoelectric potential signal, which is converted into the temperature of the measured medium through an electrical instrument (secondary instrument). Various thermocouple shape often due to the need and very different, but their basic structure is more or less the same, usually by the hot electrode, insulation sleeve protection tube and junction box and other major parts, usually and display instruments, recording instruments and electronic regulator supporting the use.

Thermistors and thermocouples are traditional electronic components for temperature measurement, both need to be in full contact with the object to be measured; the difference is that the thermistor measures the absolute temperature, while thermocouples and thermopiles measure relative temperatures, and the temperature of their "cold ends" need to be measured or compensated by the circuit to achieve the final temperature measurement.

Differences between MEMS thermopiles and conventional thermopiles

Conventional thermopile: Earlier infrared thermopile detectors were obtained by depositing thermocouple materials onto plastic or ceramic substrates using mask vacuum deposition, but the size of the device is large, the film thickness is not easy to control, and the production process is not compatible with IC production processes, making it difficult to mass produce.

With the boom in microelectronics, the concept of microelectromechanical systems (MFMs) was introduced, which led to the development of MEMS infrared thermopiles .

Currently on the market the core chip of the thermopile products, basically using the MEMS process production; according to the different thermocouple arrangement, and is divided into planar thermopile and stacked thermopile; planar thermopile and single-channel, dual-channel, 4-channel pass and other thermopile, dual-channel thermopile, can be approximated as a simple thermopile array, if the number of channels is sufficiently large and coupled with a precision thermoelectric signal readout If the number of channels is sufficiently large and coupled with precise thermoelectric signal readout circuits and supporting processing circuits, thermal imaging is possible.