SOLUTIONS FOR CONTROL OF 10% – 65% WITHOUT RESISTANCE
Humidity sensor: Basics, usage, parameters and applications
Sometimes, after the rains, the air feels damp. The water appears to be suspended in the air. However, in certain AC s, you click some buttons and the atmosphere lights up. How and why did it all happen? Moisture forms in the air, resulting in moisture. However, the humidity sensor in AC helps you to measure and evaluate it. That’s great, isn’t it? Let’s see how it does it.A humidity sensor (or hygrometer) senses, measures and reports both humidity and air temperature. The ratio of moisture in the air to the highest humidity at a particular air temperature is called relative humidity. Relative humidity becomes an important factor for comfort.A sample humidity sensorHumidity sensors work by detecting changes that alter the current or temperature in the air.There are three basic types of humidity sensors:
Capacitance
Resistor
Heat
All three types of sensors monitor minute changes in the atmosphere to calculate humidity in the air. Let us discuss these types in detail:
Capacitance
A capacitive humidity sensor measures relative humidity by placing a thin metal oxide strip between two electrodes. The electrical capacity of metal oxides varies with the relative humidity of the atmosphere. Weather, commerce and industry are the main areas of application.
The capacitive type sensors are linear and can measure relative humidity from 0% to 100%. The catch here is a complex circuit and frequent calibration. However, for designers this is less of a hassle than exact measurements and thus these govern atmospheric and process measurements. These are the only full range relative humidity meters down to 0% relative humidity. This low temperature effect often results in them being used over a wide temperature range without operating temperature compensation.
Resistor
Resistive humidity sensors use ions in salt to measure the electrical impedance of the atoms. As the humidity changes, so does the resistance of the electrodes on either side of the salt medium.
Heat
The two thermal sensors conduct electricity based on the humidity of the surrounding air. One sensor is encased in dry nitrogen while the others measure the surrounding air. Difference between the two humidity measures.
Tips for working humidity sensor
Measurement of electrolyte : An electrolyte is formed by the absorption of water resulting in a current level proportional to the humidity in the air. Gravimetric: A drying agent is exposed to moist air, resulting in an increase in the weight of the drying agent. Weight increases proportionally to the amount of moisture. Microwave / Infrared: The transmitted signal changes as the humidity increases. Attenuation is an indication of humidity in the environment.
Some parameters to evaluate
So once you know what it is and how it works, the next step is probably to test it in action. And how do you do that? By working through some of the parameters mentioned below.
Accuracy
Each sensor has its own calibration curve, based on a 9 point system. Basically, it has the advantages over the disadvantages of the particular sensor.
Linear
It indicates the voltage deviation from the BFSL value and the measured output voltage value, converted to relative humidity.
Reliability
Measurements often cause the sensor to get out of sync. However, for a sensor to be useful, it must provide reliable measurements.
Repeat
Measurements from one sensor, shall leave them uncoupled. Repeatability is a measurement of the drift between measurements of a quantity.
Response time
Typically, the time taken by the sensor to rise to 66% (rise time) or fall to 33% (fall time) of the maximum output voltage, is called response time.
The applications of the humidity sensor are far away
The applications of the humidity sensor range are far and wide. People with diseases affected by humidity, monitor and take precautions indoors using humidity sensors. A humidity sensor is also found as part of home heating, ventilation and air conditioning systems (HVAC systems). They are also used in offices, cars, humidifiers, museums, industrial spaces and greenhouses and are also used in meteorological stations for weather reporting and prediction.
We list out some projects below for reference:
Humidity Index
Presented here is a simple humidity indicator and controller. In industries such as textiles, changes in humidity have a direct impact on fabric properties, such as tensile strength, elasticity, fiber diameter, and friction. Cotton and linen require a high relative humidity (rh) around 70-80 percent because they are very brittle. Wool requires a rh level of about 65%. While silk requires between 65 and 70 percent. With this circuit, you can not only monitor the humidity level from 30 to 90 percent, but also control it.
Refrigerator temperature and humidity indicator
The small sniffer, described in this project, takes temperature and humidity from inside the refrigerator and transmits it over an RF link to a nearby receiver. The receiver checks the received code, identifies the correct sniffer device, and displays live temperature and humidity. Why do we need it you say? We can measure the temperature and humidity inside the refrigerator with the normal temperature humidity indicator but the relative humidity may not be accurate in that case.
Monitoring Humidity and Temperature Using Arduino with IoT
In this article, the humidity and temperature information from the DHT-11 sensor is graphically analyzed on the ThingSpeak platform using the Arduino MCU and ESP8266 Wi-Fi module.
Humidity indicator and controller
Presented here is a simple humidity indicator and controller. In industries such as textiles, changes in humidity have a direct impact on fabric properties, such as tensile strength, elasticity, fiber diameter, and friction. Therefore, the process is only carried out in an environment where humidity allows. Depending on the fabric and the process performed, specific moisture requirements vary. Cotton and linen must be treated at a high relative humidity (rh) of about 70-80 percent because they are very brittle. Wool requires a rh level of about 65%. Silk needs to be 65 to 70 percent processed. With this circuit, you can not only monitor the humidity level from 30 to 90 percent, but also control it.
IoT Enabled Air Pollution Meter with Smartphone Digital Dashboard
Presented here is an IoT enabled air pollution meter to monitor air quality on your smartphone using the Blynk app and Arduino board. Blynk is an Internet of Things (IoT) platform for controlling Arduino, Raspberry Pi and the like over the Internet. In this project, Blynk provides a digital dashboard on your smartphone that displays real-time air quality readings for immediate surroundings.
