The operating principles of the 5 most common types of temperature sensors today

Comprising two main components, a capacitor, and a switching circuit, temperature sensors operate based on the influence of heat on their surroundings. Although they share a common approach, the operating principles and structures of each type still have differences. Let’s explore the 5 most common types of temperature sensors with AKIA SMART HOME!

1. Capacitive humidity sensors

The capacitive humidity sensor is designed to measure humidity in the surrounding environment based on the principle of capacitance change as the humidity of the environment changes.

The capacitive humidity sensor consists of two main parts: an electrode and a dielectric material, usually a type of conductive material. The operating principle of this type of sensor is that as humidity increases, the dielectric material absorbs water and changes the capacitance of the sensor. This change in capacitance can be measured and converted into a humidity value.

Capacitive humidity sensors are commonly used in various applications, including weather monitoring, indoor automation control, smart agriculture, and various industrial applications related to humidity management.

In particular, for smart homes, when combined with Aqara smart plugs

 (ổ cắm thông minh Aqara), capacitive humidity sensors can maximize utility and create a more modern, automated lifestyle for homeowners by enabling remote on/off control and easy phone-based management.

The capacitive humidity sensor operates based on the principle of conductivity and generates temperature values

2. Thermal humidity sensors

The thermal humidity sensor is used to measure humidity in the surrounding environment based on the principle of temperature. By measuring temperature and its variations caused by humidity, this sensor can determine the current humidity level of the environment in real-time.

The thermal humidity sensor operates by detecting changes in the thermal conductivity of the environment as humidity increases, altering the temperature. Consequently, the device measures the temperature variations and infers the humidity level in the environment.

Due to its capability to accurately measure temperature, the thermal humidity sensor finds applications in the medical and healthcare sector, monitoring soil moisture and plant cultivation environments in agriculture, and controlling food storage and preservation in industries.

The thermal humidity sensor operates based on the thermal conductivity of the surrounding environment

3. Resistive humidity sensors

The resistive humidity sensor is designed to measure humidity in the surrounding environment by detecting changes in resistance based on humidity. The operating principle of the resistive humidity sensor relies on the variation in the electrical conductivity of the sensor’s material when exposed to moisture. As humidity increases, this material absorbs water, increasing resistance, and conversely, when humidity decreases, the resistance decreases as well.

By measuring resistance, the resistive humidity sensor can determine the humidity level of the surrounding environment. This sensor is widely used in applications related to humidity control and monitoring, such as in environmental control devices, medical devices, or scientific research in the environmental field.

The resistive humidity sensor can determine the humidity level of the surrounding environment

4. Thermocouple

A thermocouple is formed by two different metal wires joined together at a point called the ‘thermojunction.’ When there is a change in temperature, this device generates a voltage difference between the two ends of the thermocouple, known as thermoelectric voltage.

The operating principle of a thermocouple is based on the thermoelectric phenomenon, where each thermocouple pair generates a voltage corresponding to the temperature change. This voltage can be measured and converted into a temperature value.

Thermocouples are widely used for temperature measurement in industrial manufacturing processes (food processing, chemicals, metallurgy), human body temperature in medical devices, and various scientific research applications.

Furthermore, when combining a thermocouple with an Aqara door and window sensor (cảm biến Aqara), you can create a smart schedule where opening doors triggers the heating or air conditioning system to automatically turn on at an appropriate temperature level.

A thermocouple is designed with two different metal wires to measure the temperature of the surrounding environment

5. Pyrometers 

A pyrometer, also known as an infrared thermometer, is a device used to measure temperature based on the principle of measuring thermal radiation from an object. Instead of directly coming into contact with the object to measure its temperature, the pyrometer uses an optical sensor to measure the amount of thermal radiation emitted by the object and converts this thermal radiation into temperature values.

Pyrometers find widespread applications in various fields such as industry, manufacturing, electronics, medicine, and scientific research, where precise temperature measurement of objects is needed without direct contact.

“An infrared thermometer (pyrometer) is used to accurately measure temperature without the need for direct contact with the object

Above is the operating principle of the 5 most common types of temperature sensors today. It is hoped that with these insights from AKIA SMART HOME, you can better understand the general and specific operation of each type of temperature sensor. This understanding will assist you in selecting the most suitable product for your individual needs.