Sensors are usually divided into ten categories according to their basic sensing functions: thermal element, photosensitive element, gas sensitive element, force sensitive element, magnetic sensitive element, humidity sensitive element, sound sensitive element, etc. This section mainly explains thermal element, that is, temperature sensor. Temperature sensor is a sensor that can sense the temperature and convert it into a usable output signal. The acquisition of temperature essentially involves transferring a small amount of heat energy from an object to a sensor, which then converts this energy into an electrical signal.
Many sensing methods convert heat into electrical signals. Such as resistance detector, thermoelectric detector, semiconductor detector and piezoelectric detector. The sensor should be thermally coupled to the object for measuring temperature. Coupling can be physical or remote, but thermal coupling must always be established in order for the sensor to produce a measurable electrical response.
Coupling refers to the phenomenon that two or more circuit components or the input and output of the electrical network have close coordination and mutual influence, and transmit energy from one side to the other side through the interaction.
The temperature sensor is mainly composed of thermal element. Thermal element is made of sensitive materials whose physical properties of some objects change with temperature. There are many varieties of thermistor, the market sales are fusible alloy live thermistor insulation material, bimetallic sheet, thermocouple, thermistor, semiconductor material and so on. The temperature sensor with semiconductor thermistor as the detection element has a wide range of applications. This is because the semiconductor thermistor has the characteristics of small volume, high sensitivity and high precision, and the manufacturing process is simple and the price is low.
The primary concern of choosing the use of thermistor is its three characteristics: consistency, reliability and repeatability. The temperature detection range and accuracy of thermistor are also the main characteristics that users care about. If you want to obtain high precision thermistor, the manufacturing cost is naturally higher, how to correctly and reasonably select the appropriate precision thermistor according to the actual application situation has practical economic significance. The packaging of thermal sensor has metal and non-metal packaging form, packaging and different packaging materials. In fact, the manufacturing cost of different packaging forms is also different, so the appropriate selection of packaging forms to reduce the cost of use also has economic value.