Temperature and humidity are two parts of life that are closely related to us, but sensing these two parts is not something that can be monitored by the human eye, but needs to be detected by the physical quantity itself. Temperature and humidity sensors have this purpose and are mainly used to measure the temperature and humidity of various environments.

 With the accelerated development of social and industrial processes, the application of temperature and humidity sensors has spread to all areas of industrial life. Previously, users only had the concept of temperature alone or the concept of humidity alone.

In fact, relative humidity and temperature are closely related, and the accuracy of relative humidity can only be guaranteed by data collection of humidity and temperature at the same measurement point. This results in the need to sense humidity through sensors to replenish or reduce moisture at any time.

Because of this, temperature and humidity sensors should be mainly used in scenarios such as agricultural greenhouses, machine room inspection, warehouses, biopharmaceuticals, and cold chain transportation. In the above scenarios, there are many factors that need to be considered in the selection. The following are advices author provides you on how to buy a temperature and humidity sensor from three perspectives.

As with the measurement of weight and temperature, the selection of humidity sensors must first determine the measurement range. In addition to meteorology and scientific research departments, other departments engaged in temperature and humidity measurement and control generally do not need the full wet range (0-100% RH) measurement. 

In today's information age, sensor technology and computer technology, automatic control technology are closely integrated. The purpose of measurement is to control.Measurement range and control range together called the use of the range. Of course, for those who do not need to engage in the application of measurement and control system, they can directly choose the general-purpose humidity meter.

and control system, they can directly choose the general-purpose humidity meter.
According to the needs, users propose the measurement range to the sensor manufacturers. They give priority to ensure that sensor performance is stable and consistent in the use of the range of users, seeking a reasonable performance to price ratio, for both sides is a mutually beneficial thing.

Measurement accuracy is the most important indicator of humidity sensors, and every increase - a percentage point is a step up, or even a grade, for humidity sensors.To achieve different accuracy, its manufacturing cost varies greatly, and the selling price also varies greatly, so the user must choose an appropriate accuracy and should not blindly pursue "high-grade, precision and advanced". For example,the use of humidity sensors at different temperatures, the impact of the temparature drift to the displayed value should also be considered.

Manufacturers often give the accuracy of its humidity sensor in segmented parts, such as in the middle and low humidity section (0 a 80% RH) for ± 2% RH, while the high humidity section (80-100% RH) for ± 4% RH. And this accuracy is at a specified temperature (such as 25 ℃) of the value.

It is well known that relative humidity is a function of temperature, and temperature largely affects the relative humidity in a specified space. Every 0.1°C change in temperature will produce a change in humidity of 0.5% RH (error).

The humidity drifted with the change in temperature, so it's pointless only to talk about the accuracy of moisture measurement. So to control the humidity, we have to control the temperature first,and taht's why a large number of applications are often temperature and humidity integrated sensors and not simply humidity sensors.

In most cases, if there is no precise means of temperature control, or the measured space is not enclosed, ± 5% RH accuracy is sufficient. For the requirement of precise control of constant temperature and humidity of the local space, or the need to keep track of the humidity change of the occasion, users could choose to use humidity sensors of more than ± 3% RH accuracy.

Almost all sensors have time drift and temperature drift. In actual use, due to the impact of dust, oil and harmful gases, electronic humidity sensors can deteriorate and the accuracy will decrease over time. Electronic humidity sensor's annual drift is generally in the ± 2%, or even higher. In general, the manufacturer will mark 1 calibration of the effective use of time for 1 year or 2 years, and the sensor need to be recalibrated when it comes to expiration.

Also, other considerations should be noted. Humidity sensors are non-sealed and should be avoided in acidic, alkaline and organic solvent-containing atmospheres, as well as in dusty environments, in order to protect the accuracy and stability of the measurement.To correctly reflect the humidity of the space to be measured, the sensor should also be avoided to be placed too close to the wall or in a dead corner where there is no air circulation. If the room to be measured is too large, more than one sensor should be placed.

Some humidity sensors require high power supply, otherwise it will affect the measurement accuracy. Or the sensors may interfere with each other, or even can not work. When humidity sensors get into use, a suitable power supply shoulde be provided in accordance with the technical requirements and in line with the accuracy of requirements.

When the sensor needs to carry out long-distance signal transmission, pay attention to the signal attenuation problem. When the transmission distance is more than 200m, it is recommended to use the humidity sensor with current output signal. So how to choose a temperature and humidity sensor that suits  product characteristics? Why not try Renesas HS300X series temperature and humidity sensor.

IDT's humidity sensors offer high accuracy and the fastest measurement response time of any device in its class on the market today.The HS300x series RH sensors have an RH accuracy error of ±1.5% and a response time of 6 seconds (with a rated RH range of 20% to 80% in still air without airflow).

Since humidity sensors consume the most power when conducting measurements, obtaining a stable measurement quickly reduces the amount of sampling required. This is especially important for battery-powered applications, where lower power consumption equates to longer battery life.

In addition to its high accuracy and fast response time, the HS300x series has an excellent long-term stability of 0.1% RH per year thanks to its robust silicon carbide construction and innovative design. This not only extends service life, but also reduces effective cost.