Humidity Sensors
Humidity sensors detect and measure the quantity of water vapor in the surrounding air. They send out signals that provide critical data for a wide range of environmental control systems. Resistive humidity sensors and capacitive sensors are the most common types of humidity sensors. A resistive humidity sensor varies its electrical resistance in response to moisture in the air, offer a simple yet effective method for detecting changes in humidity. These sensors typically use materials placed between two electrodes to sense the moisture in the air.
Capacitive humidity sensors, in contrast, measure changes in the dielectric constant of their sensing material—an effect known as capacitive sensing—that is caused by water vapor in the air. Detecting relative humidity and absolute humidity are the same from the point of view of signal processing, and capacitive sensing is one of the two most common methods for measuring both kinds of humidity. Whether measuring shifts in humidity that are too subtle to notice or just detecting changes that are also hard to notice because they happen quickly, these two types of sensors are an effective means for air quality control.
More Information about Humidity Sensors
In high-performance applications, humidity sensors are calibrated for accuracy and stability, which allows them to perform consistently in warm and wet-to-dry environments. These devices are used to monitor humidity levels in cleanrooms, storage facilities, greenhouses, and laboratories. By enabling systems to automatically adjust ventilation, air conditioning, or dehumidification functions, these same sensors contribute to better comfort, product quality, and energy efficiency. The ability to continuously measure the water vapor content in these dynamic environments gives the sensors an important role in maintaining the balance of temperature and humidity.
FAQs
How accurate is a temperature sensor at measuring the temperature of the surrounding air?
To accurately measure temperature of the surrounding air, will depend on the sensor type, sensor quality, calibration, environment and signal conditioning.
Do relative humidity sensors provide an accurate measurement in humid environmental conditions?
Yes, relative humidity sensors can provide accurate measurement in humid environmental conditions when properly calibrated and maintained, though their accuracy may slightly decrease at extreme humidity levels.
Analog and Digital Control Signals: The Basics
Digital Signals
Digital signals are represented in either a true or false. There is no gray area with digital signals. An example of this might be a light switch. A light switch is either on or off. Another example of this might be a motor that is running or not running. Digital signals can be generated with both AC and DC circuits with varying voltages, currents and resistance. Some practical examples of using digital signals in an industrial environment might be if a pump is running or not running or a whether a valve is open or closed.
Analog Signals
Analog signals convey information in the form of a range. A light switch might be on or off as a digital signal, but a dimmer switch would be an analog signal. It can be on or off, but it can also be somewhere in between. A practical example of using analog signals in an industrial environment would be if there is a need to measure the level of a tank; whether it's full, empty or somewhere in between. Analog signals can take many different forms with some of the more common being a 4 to 20 milliamp signal or a 0 to 5 or 0 to 10 volt signal.
Communication
Communication in a device can either be sent or received. Whether that data is sent or received depends on the type of information. Is there a need to monitor the status of something? If so, an input needs to be received about that information. Is there a need to control something? If so, an output needs to be sent about what needs to occur. Receiving inputs and setting outputs are both things that can be accomplished by using both digital and analog signal types. Therefore, the signals are referred to as analog outputs (AO), analog inputs (AI), digital inputs (DI) or digital outputs (DO).