Week 9 - Preparing for the presentation

We met outside of class to make a video for the final presentation. We brainstormed our ideas of how long we wanted the video to be, and what would be the most simple, yet effective way of showing that out product works. One group member volunteered to wear the shoe and walk during the presentation, while another member would film the multi-meter and a third member would film the entire act. Before filming, the piezo crystals on the shoe sole were adjusted according the member's foot map to increase the mechanical energy input on them. The initial voltage reading was noted down and the person walked for 2 minutes and then the final voltage reading was read. An increase of 0.01 V was obtained, from 0.26 to 0.27 Volts. That was a success for the group. Because if the person keeps on applying the same pressure on the shoe for 4 hours, they will fully charge the battery, assuming it is an ideal system. The figure below shows the team members making some fianl adjustments before filming the video for presentation.

Figure 1: A team member placing the rechargeable battery in the case before testing and filming. 

Week 9 - Final touch

Figure1: Circuit board, the rechargeable battery and 4 piezo crystals in series attached to shoe sole

Figure2: Completed sole implemented in a shoe, with battery case attached at the back of the shoe

According to our project  timeline, we should be finishing up with everything and implementing the electrical part into an actual shoe by week 9, and we succeeded in doing it. The group members have been testing the piezo crystals with the circuit board by simply using their palms or fingers to apply pressure to the board, however, actual testing was needed. In lab this week, when we completed the shoe, one group member wore it and walked around the lab for about 1 min. A multi-meter was attached to the battery case at the back to monitor if the rechargeable battery was being charged. The initial and final voltages were compared and to make sure that the product was reliable, all 4 group members wore the shoe and walked for a minute. The increase in voltage readings were close to each other for the 4 trials, a mean of about 4 mV increase in a minute. Our prototype was ready to be shown in the presentation. We also concluded that our initial requirement of charging a 1.2 V battery in less than a day was met. Success !