December Results

Humidity Testing

To test the ion salt solutions 10 mL of water was added in each water vat along with the desired salt. For this experiment, 0.1426 grams of Potassium Sulfate and 0.5847 grams of Potassium Nitrate per milliliter were used. Three of the vats contained Potassium Sulfate while one of the vats contained Potassium Nitrate. The ratio of salt solutions were determined using a saturated solution chart based on temperature as seen in Figure 1 and Figure 2. At the time of testing, thermoelectric blankets had not been received and were unable to be used, therefore a hotplate from the BAE chemistry lab was used as a heat source. To maintain a constant temperature a probe connected to the hotplate was placed inside the chamber for readings to turn on and off the heat. Then the BME 280 sensor was connected to an Arduino Uno and the serial port monitor was used to measure temperature and humidity.

As soon as we put the salts in the chamber, the humidity increased drastically (from 18% to 40% within 2 minutes). The hotplate originally overshot the desired temperature of 37°C by a few degrees while the humidity readings were collected throughout the entire temperature range for future reference. One realization was that the humidity finally rose once the temperature of the water in the vats reached 37°C which took longer than the surrounding air which was what the probe and sensor were measuring.

In this test, we did not achieve our desired humidity of 95%. Several factors could have affected the results. We noticed that a large amount of condensation appeared on the “ceiling” of the chamber; using a new lid with a domed shape may alleviate this problem. We also observed that even tiny disturbances to the chamber, such as rotating the lid slightly without lifting it, caused changes in humidity of up to 5% which could be solved by creating a more secured environment that does not require movement of the chamber.

It is also possible the salt baths need a larger volume for spare amount of water to be around if the chamber is going to house cells for up to 10 hours. In our next test, we will fill the baths with 20 mL of water instead of 10 mL, and the corresponding amount of salt needed for saturated solutions. This will give us a better idea on the humidity standpoint and how much water is removed for determination of lasting amount after several hours of use are needed.