Element I: TESTING AND DATA COLLECTION AND ANALYSIS

TEG Power Test:

When put under optimal conditions of a significant heat difference, we were able to generate a voltage of .6v from just one TEG. While this number is lower than our required minimum, that is just because it is the voltage from one TEG. So with both TEGs in action, we would have a total of 1.2v which does in fact meet our requirements. The test results are accurate and repeatable because we used a thermometer on each side of the TEG and kept everything at a consistent setting to be able to replicate it. However, we did notice that the “cold” side of the TEG would occasionally be left warm after the test due to the heat of the other side which might reduce efficiency. With a total output of 1.2v from the TEG, we would not achieve the same power/efficiency as a power box and wall outlet, but we should be able to generate enough power to charge the device, just at a slower but still beneficial rate. As a whole, the design functioned properly and effectively for the purposes required in our project. To improve our design for the future, the most important aspect to consider is to ensure that we are able to create a clear and distinct separation of the temperatures and consistently maintain that difference. One possible solution to ensure this could be to add an aluminum plate to the cold side so that it can retain and better absorb the cold from the outside air to help boost our efficiency. We also need to ensure sustained contact with the heat coming from the skin so we need to ensure a tight connection of the frame with no movement so that the increased time under heat so that the difference in power we are missing can be made up by longer time of activity.

Frame Security Test:

The device, while worn for several minutes of strenuous exercise and movement, was deemed comfortable by the user. All of the parts remained perfectly secure throughout the whole process and showed no signs of damage or loosening. There were little to only minimal indentations on the arm but nothing significant or painful that had much impact on the user. This means that the current state of the device does meet the requirements for comfortability we needed. However, with additional components we would need to ensure that they would also be properly secured. To improve our device, we could increase the stability of the current parts as well as the future parts to be installed by moving the velcro strap on top of the USB port cover to add additional tightening to the connection of the parts there. Additionally, this could increase the comfortability as it gives the velcro straps more allowance and does not require as tight of a connection. We could also increase the accuracy of the testing procedure by testing wearing the device while doing other exercise activities like biking or working out by lifting weights for example.

USB Breakout Board Test:

We were not able to create any sort of working connection with the USB port part we were using. There was no measured output when the device was connected to the USB at any of the ports or in any combination with the type of input wires we had. With our current knowledge of the wiring and the parts available to us for our prototype, we do not believe that the USB port we have will be able to function properly in the setting of our device. Because our part is not currently working, our current plan is to scrap the part entirely on our device and instead connect it straight to the wire. We researched and discovered a method that would allow us to connect the power and ground cables that the TEG outputs straight into the middle of a wire. For this output, we could connect it straight into a lightning cable to charge a phone or into a wire with a female USB port opening for added versatility of charging different devices but it would require additional wires.

TEG Surface Area Test:

The surface area of the TEGs on the upper forearm passed our requirements with flying colors. Our requirements only needed 90% coverage of contact with the skin yet our device was able to manage nearly 98% coverage when kept on the arm for an extended period of time. This is more than we needed and will ensure that the TEGs are able to function properly and efficiently in the setting we are applying them. The test was ensured to be kept accurate and repeatable because we averaged the area of contact with both TEGs at their respective positions and scanned it into a 3D modeling software to get the most accurate data on the area that accounts for all the various curves and spots of paint on the arm. The method of testing was very optimized and gave clear calculated results. However, this was also under optimal circumstances with limited testing. To get more accurate and informative data, we could check the surface area of skin contact we are able to get when applied like how a user would be using the product and with different arm types since everyone’s shape and size of their arm is different.