the dew point is the temperature at which the water vapor in air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. At temperatures below the dew point, water will leave the air. The condensed water is called dew when it forms on a solid surface.
The dew point is a water-to-air saturation temperature. The dew point is associated with relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. Relative humidity of 100% indicates the dew point is equal to the current temperature and that the air is maximally saturated with water. When the moisture content remains constant and temperature increases, relative humidity decreases.
The wet and dry bulbs are made from glass tubing , I purchased the glass tubing from eBay size 5 mm diameter x 100 mm length.
I prepared these tubes myself, if you are going to use glass tubes have them prepared by someone who is experienced in working with molten glass, or you could use plastic acrylic tubing instead.
The first thing was to close one end of the tube. The wet tube has a slight kink and has a flat rounded edge slightly larger than the diameter of the tube, this will allow the cotton wick to stay in place the dry tube has a rounded bottom.
The next stage was to solder connecting wires to the temperature chip in this project. I am using the surfacemount as I had some lef tover from a previous project, when I was happy with the soldering I pushed the temperature sensor chip into the glass tube so the chip comes in contact with the bottom of the glass tube. I used some proxy resin to seal the top end of the tube.
To make the bracket I used some flat plastic cocktail stirers ,to bend the plastic I used the heat from a candle, slowly warming plastic until it was soft enough to bend around the glass tubes. I don't recommend this if you have no experience working with plastics, I suggest using slightly larger diameter tube glueing them to the straight pieces of plastic, please see diagram.