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What Is The Temperature And Humidity Sensor? And How To Select It?

temperature and humidity sensor

What is temperature humidity sensor?

Temperature and humidity sensor (or rh temp sensor) is devices that can convert temperature and humidity into electrical signals that can easily measure temperature and humidity. Temperature humidity transmitters on the market generally measure the amount of temperature and relative humidity in the air, and convert it into electrical signals or other signal forms according to certain rules and output the device to the instrument or software to meet the environmental monitoring needs of users.

How does temperature and humidity sensor work?

Temperature and humidity sensors measure various substances based on changes in their electrical characteristics when temperature and humidity change. Depending on the type of sensor, the principle of operation varies. The operating principles of several common temperature and humidity sensors are described below.

1. Resistive temperature and humidity sensor working principle

The resistive temperature and humidity sensor measure the temperature and humidity in the air using an internal temperature-sensitive resistor (RTD) and a moisture-sensitive element resistance. The resistance value of this detection material changes with temperature and humidity and is converted into a corresponding electrical signal that outputs a temperature and humidity value.

2. Capacitive temperature and humidity sensor working principle

The capacitive temperature and humidity sensor working principle that the dielectric constant of a material changes with temperature and humidity. When the dielectric constant of the material changes, the inductive capacitance will also change accordingly, thus outputting the corresponding temperature and humidity values.

3. Electrothermal temperature and humidity sensor working principle

The electrothermal temperature and humidity sensor measure temperature and humidity by utilizing the heating and cooling process of an electric heating element. And the value of temperature and humidity is obtained by measuring the change in resistance value. They usually consist of a heating element, a temperature sensor and a humidity sensor.

What is the principle of humidity transducer explain?

The components of the temperature and humidity sensor module mainly include a humidity sensitive capacitor and a conversion circuit. The humidity sensitive capacitor is composed of a glass substrate, a lower electrode, a humidity sensitive material, and an upper electrode.


Humidity sensitive material is a kind of high molecular polymer, its dielectric constant changes with the relative humidity of the environment. When the environmental humidity changes, the capacitance of the humidity sensitive element changes accordingly. That is, when the relative humidity increases, the humidity sensitive capacitance also increases, and vice versa. The conversion circuit of the sensor converts the change in humidity-sensitive capacitance into a change in voltage, which corresponds to a change in relative humidity of 0 to 100% RH. The output of the sensor shows a linear change of 0 to 1v.

Where should a temperature humidity sensor be placed?

First, get as far away from electronic and electrical equipment as possible. Second, mount the sensor vertically, at least 6 feet above the floor. Finally, choose a location in the center of the room or in a well-ventilated area to ensure that the sensor accurately reflects the humidity of the entire room.

How to Pick the Best Temperature and Humidity Sensor for Your Project?

First of all, the frequency response characteristics: the frequency response characteristics of the temp and humidity sensor determine the frequency range be measured, and the measurement conditions must not be distorted within the allowable frequency range. In fact, the sensor response always has a certain delay. The better. The frequency response of the sensor is high, and the frequency range of the measurable signal is wide. Due to the influence of structural characteristics, the inertia of the mechanical system is large. The frequency of the measurable signal of the sensor with a low frequency is low.

Secondly, the linear range: the linear range of the temperature and humidity device refers to the range in which the output is proportional to the input. In theory, within this range, the sensitivity remains constant. The wider the linear range of the sensor, the larger the range, and it can ensure certain measurement accuracy. When selecting a sensor, when the type of sensor is determined, it is first necessary to see whether its range meets the requirements.

Finally, stability: the ability of the temperature and humidity device to remain unchanged after a period of use is called stability. In addition to the structure of the sensor itself, the factors that affect the long-term stability of the sensor are mainly the use environment of the sensor. Before selecting a sensor, you should investigate its use environment and select the appropriate sensor according to the specific use environment.

What about the RENKE sensor?

The RENKE sensor adopts a large-size LCD screen and keys. Built-in high-quality temperature humidity sensor module imported from Switzerland, with high

measurement accuracy, strong anti-interference ability, etc, to ensure the excellent measurement performance of the product. The temperature and humidity are automatically monitored, the value is displayed on the LCD screen, and the data is also uploaded to the monitoring software through RS485, or wifi signals.

Our temperature and humidity sensor collects data every 2s. By default, it uploads data every 20s. It also supports adjusting the data upload frequency (1S~10000S/time can be set) according to the usage environment and the freedom of the recording period between 1 minute and 24 hours Settings. Its internal integrated alarm module (buzzer or relay), we first set the upper and lower limit values of temperature and humidity through the button, once the value exceeds the limit, it will realize the sound and light alarm in place. At the same time, our temperature and humidity sensor also has a powerful storage function, Up to 65000 sets of records can be stored.

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