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The History of Hygrometer

Jun 30,2021 | Meawow

What is a Hygrometer?
Hygrometers are considered weather instruments that can measure humidity. Over the centuries, these instruments have changed, advanced, and have taken different varieties to suit the users’ needs. It was in the 1400s when one of the very first models of hygrometers appeared. Leonardo da Vinci constructed his early version of this device in which his goal was to measure the moisture in the air.

He had a genuinely clever design, which centered around a gauge that had absorbent and non-absorbent materials on each side. Whenever humidity would increase, the side with the absorbent material would get heavier as it got more saturated. The weight difference was interpreted as a reading for a relative humidity.

After a few hundred years, Horace Bénédict de Saussure, a physicist, and a geologist from Switzerland who loved to explore the Swiss Alps created an improved version of the early hygrometer. Just like what da Vinci developed, the device measured humidity.


The difference though is that de Saussure used a strand of hair, which was suspended on the device under tension. The moisture in the air had an effect on the hair, causing it to either contract or expand, depending on the humidity level. A needle would point to a number on the dial, which he interpreted as the humidity in the air.

Other versions of the device were created. Most of the early designed replicated thermometer technology during that time. To be specific, the devices borrowed the techniques used in wet and dry bulb psychrometer. It had two mercury thermometers, which as the name implies, had one dry and one wet. The latter had a wet fabric sleeve covering it at the base of the device. To measure relative humidity, the difference in the temperatures of the dry and wet thermometers was calculated.

How the Hygrometers Work?
Today, there are different types of hygrometers and how they work will depend on their design. For instance, one of the types is a capacitive hygrometer. Devices classified under this form use different other types of sensors. Capacitive hygrometers are created for applications where price, fragility, or space is a concern, so they risk the accuracy of reading moisture for the affordability of the device.

Capacitive hygrometers measure the effect of moisture on a metal oxide material. Frequently, they are also used for quantifying humidity's impact on the dielectric constant (or the relative permittivity) of a polymer, such as synthetic plastics. When calibrated, the sensors have an accuracy rating of ±2% relative humidity within the range of five to 95% relative humidity.
If not calibrated, the accuracy is up to three times worse. The sensors though can withstand high temperatures and the effects of condensation, and they are suitable for various applications. However, these capacity hygrometers have sensors that can easily be contaminated and show signs of aging rapidly.

Another sensor is resistive, which is less sensitive when compared to capacitive sensors. These sensors measure the changes in a material's electrical resistance, which humidity in the environment causes. Since they are not as sensitive as capacitive, resistive sensors require a more complex circuit board. The accuracy depends on the resistive material used but is usually up to ±3% relative humidity. The material also dictates how robust the hygrometer will be against condensation.

What is a Hygrometer Used For?
Hygrometers are deemed as useful tools, which utilize calculation and calibration of pressure and temperature changes. Combined together, the resulting percentage will be the amount of moisture in the air. A hygrometer is a helpful device in office buildings and homes, as well as in manufacturing and industrial processes. Especially in homes with children and the elderly, a good thermometer and hygrometer  can quickly help you identify the living environment and prevent some diseases in advance.

How to Use a Hygrometer: Reading the Device
Whether you will use a hygrometer for weather observation or measuring conditions for indoor spaces, it makes sense to know how to read one. To get the best and most accurate results, these devices need to be calibrated at least once every year.

For digital hygrometers,  just let the device work for at least one minutes so it can adequately detect the temperature of the air. You do not have to perform any other calculations because the instrument will do it for you. An example of a digital hygrometer is Meawow Thermo-hygrometer  Electronic ink Display Vision, which is suitable for both indoor and outdoor use.

For homes, the Meawow Electronic-ink Screen Display Temperature and Humidity Sensor is an easy-to-use device for monitoring humidity and temperature. This digital device will provide you with the current humidity also the current temperature. The electronic ink screen design provides a 180-degree wide-angle for reading  while also protecting your eyes.

With these hygrometers, homeowners and businesses can keep their properties or products in prime condition. At the same time, they promote recognition of the ideal humidity in a specific area to increase its overall comfort level.