Guide to Vaisala’s Humidity & Temperature Sensors

Precise control of humidity and temperature in manufacturing isn’t just beneficial but essential. Issues with temperature and humidity can lead to product defects and impact equipment performance, especially in the food and beverage and medical industries.

If you’re looking for reliable, high-quality temperature and humidity sensors, look to Vaisala. They’ve been an industry leader since 1973 and engineered the world’s first thin-film polymer-based capacitive humidity sensor. Since then, Vaisala’s sensors have set the standard in environmental monitoring. Their core sensors are designed to accurately measure humidity and temperature in a range of challenging conditions, supporting critical applications from HVAC systems to pharmaceuticals.

In this product overview, we’ll discuss Vaisala’s core HUMICAP® sensor technology and best-selling products, including HMM100, Indigo500®, and DRYCAP®.

HUMICAP® Technology

An illustrated image showing how Vaisala's HUMICAP sensor is structured. IT shows a break down highlighting the upper electrode, the thin-film polymer, lower electrode, and glass substrate.
                   Image from Vaisala’s website

First introduced in 1973, HUMICAP® technology is the core of Vaisala’s temperature and humidity sensor lines and is critical for monitoring conditions and processes in many industry applications, from automotive and aviation to data centers, cleanrooms, and other critical environments.

These sensors define quality and reliability, providing accurate and stable measurements of relative and absolute humidity, temperature, dew point temperature, wet bulb temperature, mixing ratio, water vapor pressure, and enthalpy.

Primary Benefits & Features

The primary advantages of sensors/probes equipped with HUMICAP® technology include:

  • Accurate to ±0.8% relative humidity
  • Reliable data traceability
  • Resilient to dust and most chemicals
  • Optional chemical purge
  • Sensor heating
  • Condensation recovery


A group of temperature and humidity sensors in the HMM100 product line by Vaisala
                     Image from Vaisala’s website

The HMM100 is one of the most popular offerings from Vaisala, although it’s not part of a standard product series like the Indigo500®products. Featuring Vaisala’s core HUMICAP® technology, this open-frame humidity module is designed to measure relative humidity and dew point in high-temperature applications, including heat sterilization. It’s also designed to be easily integrated into environmental chambers and incubators.

Based on the application, the HMM100 can be constructed with stainless steel or plastics and is available in standard and extended (400 mm) lengths.

Primary Benefits & Features

  • Exceptional measurement accuracy thanks to its 180R sensor
  • Wide temperature range (-70 degrees Celsius to over 180 degrees Celsius)
  • Easy field calibration due to integrated trimmers
  • Virtually maintenance-free

Indigo500® Series

The HMP1 temperature and humidity probe, part of Vaisala's Indigo500 family.
            HMP1 image from Vaisala’s website

The Vaisala Indigo500® family is a customizable and modular instrument platform that improves process measurement. In addition to sensing probes, the Indigo500 series also includes transmitters and software to monitor and integrate data easily.

Primary Benefits & Features

All probes within the Indigo500® series are known for their long-term stability in measuring absolute and relative humidity, temperature, wet-bulb temperature, dewfrost point temperature, water concentration, water vapor saturation pressure, and more. All Indigo500® products feature integrated HUMICAP® technology.

Other benefits and features of Indigo500 probes include:

  • High accuracy
  • Compact design
  • Easy plug-and-play connection with Indigo500® transmitters

Indigo 500® Products

The following products are part of the Indigo500® family of probes:

  • Humidity and Temperature Probe HMP1: Ideal for indoor spaces and can be wall-mounted.
  • Humidity and Temperature Probe HMP3: Primarily used in ducts.
  • Relative Humidity and Temperature Probe HMP4: Best used in high-pressure or vacuum environments.
  • Relative Humidity and Temperature Probe HMP5: Ideal for high-temperature applications.
  • Relative Humidity and Temperature Probe HMP7: Similar to the HMP5, it’s best used in high-temperature applications or condensing environments.
  • Relative Humidity and Temperature Probe HMP8: Commonly used in high-pressure environments or for leak-tight installations.
  • Relative Humidity and Temperature Probe HMP9: Ideal for rapidly changing environments.
  • Temperature Probe TMP1: Only used in demanding temperature measurements and doesn’t measure humidity.


The DMP80, a temperature and humidity sensor by Vaisala that features their DRYCAP® technology.
                       Image from Vaisala’s website

DRYCAP® sensors are used in many environments with arid conditions, especially in industrial applications with low gas humidity.

Unlike previous products that experienced sensor drift, the DRYCAP® series performs reliably in extremely hot and dry conditions. Typical applications range from plastics and food baking to lithium battery manufacturing.

Features & Benefits

The primary benefit of DRYCAP® is its ability to remain stable in extremely hot and dry conditions.

Other benefits include:

  • Auto-calibration function
  • Wide measurement range (-80 degrees Celsius to over 100 degrees Celsius)
  • Accuracy to ± 2 degrees Celsius
  • SI-traceable measurements
  • Long-term stability
  • Minimal maintenance (calibration recommended after two years of use)
  • Rapid response
  • Exceptional condensation recovery
  • Highly resistant to many chemicals, oil vapor, and particulate contamination

DRYCAP® Products

There is only one product in the DRYCAP® series—the IP67-classified DMP80. It’s portable and robust, can work with the Indigo80® handheld indicator and data logger for multi-parameter measurements, and is suitable for ambient and pressurized processes.

Learn More About Vaisala’s Sensors

Find high-quality products from Hi-Watt. We’re proud to be Michigan’s leading regional distributor of industrial heating solutions. We carry a wide range of products, including Vaisala sensors/probes and transmitters.

Please contact us today if you have questions about these products or want to request a quote.