Week 7 - Humidity Sensors

D. Barbalace

A humidity sensor, or hygrometer, is used to measure moisture content in the atmosphere.  These instruments usually base their readings off of a more easily obtained quantity and are then calibrated to calculate a measurement of humidity.  The most common quantities used to measure humidity in modern hygrometers are the dew point and the electrical capacitance or resistance of the air.  For as little as $10, someone can purchase a simple Arduino humidity sensor (that utilizes electrical capacitance) for use in a home project.  This sensor is the size of a quarter!  While this type of sensor is not preferable in an industrial setting, its perfect for small projects at home or school.

Humidity sensors are an essential part of the operations of many building systems.  They are often used in manufacturing when a certain process needs to take place in a particularly dry or moist environment.  Greenhouses need hygrometers to ensure that the humidity is at a healthy level for the plants growing within.  Saunas rely heavily on comfortably high humidity levels.  Museums must ensure that humidity sensors are installed near sensitive artifacts so that the old materials are not damaged by moisture levels in the air that are too high or too low.  High quality musical instruments, especially acoustic guitars and string instruments like the violin and cello, must be kept in a controlled, humid environment to keep the wood in its best condition.

Moisture control is equally important in residential buildings.  HVAC systems contain humidity sensors that help keep humidity at comfortable and healthy levels.  Dry conditions can cause skin irritation and dehydration, while overly moist conditions can increase growth of unfavorable organisms.  Since humidity is such an essential part of human comfort, nearly all modern HVAC systems contain some type of hygrometer.

References:

https://www.sparkfun.com

http://en.wikipedia.org/wiki/Hygrometer

Comments:

On Ian Lagrange's Post:

Why is there an option to sign out directly under the comment box? I just wrote an entire comment and then I hit 'sign out', thinking it was 'publish,' and I deleted my entire damn comment. So here we go again:

I like how you focused on the safety aspects of motion sensors. They're widely used in alarm systems, automatic lights, and automatic doors, but it seems like people have started forgetting they're even there. When I was in 8th grade, they installed motion sensitive lights in the new addition to the middle school, and everyone thought it was amazing. Since then, I haven't seen a single building in the medical, business, or education fields get constructed without automatic lights somewhere in the building.

On Tyler Woyshner's Post:

I wanted to read your post because it is closely related to my post, which is about humidity sensors. Both temperature sensors and humidity sensors are incredibly important in HVAC design, and humidity is dependent on temperature. Both are important for health and comfort in a building. As you mentioned, closed-loop A/C systems can be optimized by turning off the system once a space has reached the desired temperature. Keeping humidity at a desired level will also aid in energy optimization, as the temperature is more likely to remain constant when the moisture content remains steady as well.