Unexpected places where you can find a moisture sensor

What is relative humidity?

Relative humidity (RH), expressed as a percentage, describes the amount of water vapour present in the air compared to the maximum amount the air can hold at a given temperature. The U.S. Environmental Protection Agency (EPA) highlights the importance of maintaining indoor relative humidity below 60% and ideally within a range of 30% to 50%, as excessive humidity can promote mould growth and associated health risks.

Conversely, air that is too dry may lead to dehydration, skin irritation, nosebleeds and an aggravation of respiratory conditions such as asthma.

Accurate humidity measurement is therefore essential across a wide range of industries, including:

Production

Many components used in electronics manufacturing and assembly are highly sensitive to moisture. If the air is too dry, electronic components can become brittle and more prone to damage. In addition, low-humidity environments increase the risk of electrostatic discharge (ESD), which can occur when charged objects come into contact and static electricity is released. This may lead to equipment damage, fire hazards and other safety risks.

In textile manufacturing, insufficient humidity can also reduce tensile strength — the maximum force a fabric can withstand before breaking. Damage to threads during processing can negatively affect production efficiency and result in increased machine downtime.

Agriculture, farms, and food

When products are stored in warehouses, transported to retail locations and refrigerated prior to purchase by the consumer, it is essential to know the environmental conditions they are exposed to at every stage of the supply chain. Temperatures and humidity levels outside the specified range can cause products to spoil before they ever reach the end customer.

Humidity control is also critical in hatcheries and egg incubators. If the air is too dry, eggshells can adhere to the hen during laying, making the eggs unusable. Conversely, excessively humid conditions can promote bacterial growth, posing a risk to both product quality and hygiene.

Healthcare

Many healthcare devices rely on data from humidity sensors, including CPAP machines, ventilators and incubators used for premature infants or babies with jaundice or respiratory conditions.

In neonatal care, incubators regulate temperature, oxygen concentration, humidity and light. Humidity control is particularly important for protecting the infant’s skin, which does not fully mature until around 34 weeks of gestation. Infants born before this stage have especially thin and sensitive skin, making precise humidity regulation essential.

Transport

Knowing the humidity level inside a vehicle cabin — whether in agricultural machinery, industrial vehicles or passenger cars — is important not only for occupant comfort and well-being, but also for monitoring conditions that may affect the batteries powering many modern electric vehicles (EVs).

Excessive moisture exposure in lithium-ion batteries can lead to reduced performance and shortened battery life, making reliable humidity monitoring an important factor in vehicle and battery system design.

The role of moisture sensors and important considerations when selecting a sensor

Humidity sensors play a crucial role in monitoring humidity and, in many cases, temperature across a wide range of applications. They alert users when humidity levels exceed or fall below defined thresholds. When selecting the appropriate humidity sensor, several key factors should be considered, including:

Operating environment: Humidity sensors may be used in dusty environments where filtration is required, or in conditions involving condensation or chemical exposure. For example, in refrigerated environments used for food storage, condensation can indicate excessive moisture and may lead to spoilage, requiring the sensor to trigger corrective action. In agricultural applications such as poultry housing, the presence of ammonia means the sensor must be chemically compatible.

Required humidity and temperature range: It is important to define the operating humidity and temperature range in advance, as most applications do not require measurement across the full 0% to 100% RH range. The total error band (TEB) across the defined operating range should also be specified.

Output type: Consider whether a digital or analogue output is required and whether the signal will be processed by a microcontroller, alarm system, digital-to-analogue converter (DAC) or programmable logic controller (PLC).

Supply voltage: The required supply voltage (e.g. 2.3 Vdc, 3.3 Vdc or 5 Vdc) should be defined, as well as whether the application is battery-powered and requires low-power or sleep-mode functionality.

Honeywell’s portfolio of humidity sensors offers a wide range of options, including digital and analogue outputs, filtered and unfiltered designs, and SMD or SIP packages. These sensors are known for their reliability, high accuracy, robustness and long-term stability, even in demanding environments.

If you would like to learn more about the latest humidity and temperature sensor solutions, such as the HIH8000 Series, please contact us today.