Initial Design

Our final design is the result of a progression of ideas. We started with a simple concept of aborbing pads and using conductivity measurement to correlate level of dehydration. We used wool, cotton blend to collect the sweat and once the water evaporates, the salt content of the sweat deposits on the pad and we can measure the conductivity of this pad.

Intermediate Design

The next step was to convey this information to the user through visual indicators, like blue for hydrated, yellow for initial stages of dehydration and red to denote dehydration at a level to take action. We went back to the drawing board researched on wearables and electronics that go with it.

Final Design

We had several failures in obtaining a good correlation with the conductivity alone. We continued our research and decided to use a poly gel formed from hydroxyl propyl methylcellulose (Hypromellose). This gel hydrates and forms layers thus preventing water from leaving the device. The trapped water will cause the poly gel to swell and strain a carbon nanotube sensor to measure volume. This technique would help us find the amount of water in the sweat. Further a breakthrough in technology in measuring salt contents at nanogram level resulted in us using this to measure the weight of the salt. With this idea, we were able to estimate the concentration of salt, a strong indicator of level of dehydration. Additional support for concentration would come from conductivity measurement of the salt using solid state circuitry