Group C: Humidity Sensor

Humidity can be defined as the quantity of moisture (water) in the air. The warmer the air is, the more moisture it can hold. Relative humidity is a percentage that helps quantify the amount of moisture in the air. It is the ratio of the moisture present in the air to the maximum amount of moisture the air can hold at that temperature. A humidity sensor would measure and report this quantity. Most humidity sensors work by using a “capacitive measurement” system [1]. These sensors use two metal plates and a non-conductive film that will collect the moisture in the air. The moisture will cause voltage changes between the two plates, which in turn will be converted into digital readings of the air relative humidity. 
   

These sensors are used in residential, office, and even industrial settings. Humidity sensors can be integrated into the HVAC system in order to constantly monitor and control indoor air moisture levels. Humidity sensors are important because humidity affects human comfort, and can even cause health concerns. Indeed low humidity can cause breathing problem or joint pain, and high humidity can cause mold and fungus growth [2]. In an industrial setting, certain processes are very sensitive to humidity, and the moisture in the air must be maintained around a certain level. Paper production or pharmaceutical processes for instance.  

Sensors definitely play a very important role in the development of intelligent buildings. Sensors help with the automation of certain processes in the building. A robots functioning with a humidity sensor could automatically regulate the amount of air blown into a room to maintain an appropriate relative humidity.

I had a basic understanding of the use of humidity sensors, although I did not know exactly how they functioned. Doing research actually made me aware of the crucial role humidity sensor play in day to day operation of a building. When think about indoor air comfort, we often focus on temperature, but relative humidity is very important. As I stated bellow, certain levels of moisture are responsible for health problems in residential homes. In a city like Philadelphia where temperature range from 10°F to 95°F annually, constantly monitoring the humidity in the air becomes even more important.

Comments on others posts:

Matt’s post: I found your post very interesting. As I stated in my own, I have taken for granted a lot of the things sensors do in a building. I would have thought pressure sensors would only be useful in medical settings when keeping a patient in isolation. I had never considered how it is used in the HVAC and plumbing system. Your pictures were also a very good idea. I helped understand the concepts and the functioning of the sensors better. Your post mentioned the use of pressure sensor to keep workers and occupant safe in high rise building. Is the technology already being used, or is it a prediction?

Yoon’s post: I liked that you found so many more example of humidity sensor. It was nice to see the different options out there. I only discussed the “Capacity” polymeric sensor. I also like that you mentioned the limitation of both system. I chose to focus on their role, as well as their possible future application. Reading the other blog posts, I felt that sensor are getting more and more precise and effective. Do you think that there are less common sensors that can perform better than the ones you mentioned? 

References:

[1] "Humidity Sensor." EngineersGarage. N.p., 2012. Web. 18 Feb. 2014.

[2] Erdemir, J.S. Metzker, and C. Wilborn. "What Is a Humidity Sensor." WiseGeek. Conjecture, 17 Jan.
      2014. Web. 18 Feb. 2014.