Vaisala HUMICAP® Technology
Pioneering technology innovation for modern humidity measurements
Today, Vaisala is a leading provider of humidity measurement probes to multiple industries and in many applications. Relative humidity sensors are now an industry standard. Here is how it started.
We need to fix this
Up until the early 1970s, hair hygrometers were widely used despite the unreliable humidity measurements they provided. To address this, Vaisala embarked on the development of a novel humidity sensor employing semiconductors and thin-film materials.
HUMICAP® is born
At the CIMO VI congress in 1973, Vaisala introduced the HUMICAP®, the world's first thin-film capacitive humidity sensor. This groundbreaking innovation revolutionized humidity measurements. The HUMICAP sensor had no moving parts and thanks to the advanced utilization of semiconductor and thin-film technologies, it was amazingly small in size.
From one company’s invention to a global standard
Since then, Vaisala has emerged as the market leader in relative humidity measurements, and thin-film capacitive humidity sensors have transcended being one company's invention to a global industry standard.
Constantly evolving
HUMICAP is not only a sensor, it is a solution to many challenging measurement positions and conditions. HUMICAP is in Vaisala's core and we develop it constantly.
If it works on Mars, it works anywhere
The unforgiving conditions in space pose strict demands on technology, requiring the most reliable sensors that can be trusted to endure without repair. You simply cannot venture out into these conditions with just any instrumentation. Therefore, the HUMICAP products were a natural selection to measure conditions in the planet MARS since 1990s.

HUMICAP in numbers
launched
of measurements based on HUMICAP
planets
HUMICAP - The tiny giant
Humidity is everywhere. It affects our comfort, health, and productivity. It also influences the quality and safety of many products and processes. That’s why measuring and controlling humidity is essential in many industries and applications.
HUMICAP is not only a sensor, it is a solution.
Watch the introductory video of the tiny giant.
How it works
HUMICAP is a capacitive thin-film polymer sensor consisting of a substrate on which a thin film of polymer is deposited between two conductive electrodes.
The electrode facing ambient air is made of porous metal to protect the sensor from contamination and exposure to condensation. The substrate is typically glass or ceramic. The thin-film polymer either absorbs or releases water vapor as the relative humidity of the ambient air rises or falls.
The dielectric properties of the polymer film depend on the amount of absorbed water. As the relative humidity around the sensor changes, the dielectric properties of the polymer film change, and so does the capacitance of the sensor. The instrument’s electronics measure the capacitance of the sensor and convert it into a humidity reading.

Customer testimonials
"When you find products – and a company – you can trust,
"The Vasa Museum wanted accurate and reliable measurement instruments.
“At Viking Malt we work very hard to ensure the production of consistent, high quality malts.
Condensation prevention technology with warmed probe
One of Vaisala's innovations in the humidity measurement field includes warmed probe technology for the toughest high humidity environments. Saturation in the environment causes condensation to form on all surfaces including measurement sensors, which can be fatal for some technologies. A warmed probe keeps the sensor continuously above the ambient temperature, ensuring condensation never forms. With Vaisala's solution, relative humidity measurement is possible in these conditions with an additional Indigo520 transmitter.
In the visualization, the Vaisala HUMICAP® probe A has a heating functionality, whereas the probe B is non-heated. When 100% relative humidity (RH) is reached, probe A recovers quickly to show accurate humidity readings whereas B recovers very slowly. Depending on the device, recovery can take hours.

Unique benefits
Excellent long-term stability and repeatability
Insensitive to dust and most chemicals
Fast response time
Sensor heating
Full recovery from condensation
The most reliable and accurate humidity measurement
HUMICAP® applications by industry
Even though the HUMICAP innovation was originally designed for a new type of a radiosonde, the word got around about reliable humidity measurements, and created a growing demand in many industries and applications. Today we offer everything you need for measuring humidity, with a wide range of humidity instruments covering applications from HVAC to the most demanding industrial applications, both indoors and outdoors.
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Examples of HUMICAP® products

Indigo Family - the modular platform

HUMICAP® Humidity and Temperature Probe HMP155

Humidity and Temperature Probe HMP110
