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 ! 

Presentation Time!

Figure 1: Graph showing voltage over time

We had our presentation in Engineering on Tuesday! We didn't win the nomination for our team section, but we're still going to continue as hard as we can with our project. Our idea still is a very viable one and could help a lot of people if put in the right direction. Before the presentation, we did one last check to make sure we were storing energy, and we were! The Matlab plot showed that after it was charged up, it had a constant 5 volts that would allow it to charge a battery.

Week 7: Electrical Components complete

Completed Piezo circuit

The final product of our electrical design is complete. After numerous circuit diagrams and multiple bread board designs the most voltage efficient circuit was created. The final circuit board actually runs similar to a breadboard design, with a copper wire running through one entire end of the board. While creating the circuit, we made a mistake in attaching the first copper wire, as it turned out to be from some sort of resistor component. We also 3D printed another piezoaqueduct for our final mechanical design. Along with this, we learned to utilized an arduino to collect real-time voltage data to display data.

Piezo crystals hooked up to arduino

Week 6, 3D Print

Image 1: 3D printed piece

Image 2: Intended function; blue:force; orange:tool; green:piezocrystal

3D PRINT SUCCESS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The purpose of this piece is to direct the input force onto the piezo crystals. Since the crystals actually produce voltage from distortion and shearing, a sharper directed force produces better electricity. The modeled aqueduct-like structure, dubbed the "piezoaquaduct", focuses the relatively spread out pressure onto specific points in the crystals. This simple mechanical feature should greatly increase the yield of the piezoelectric generator.

Week 6, Engineers make a Quantum Jump

a circuit diagram showing the various component
used to charge the battery

After several weeks of research and experimentation, we finally set up the right circuit diagram which was able to increase the voltage of a 1.5 volt rechargeable battery from about 0.03Volt to 0.04volt during our first test. this value showed a general increase with further testing. although this voltage increase is not that huge of a value, we used only one piezo to perform this experiment and also our circuit lacked a DC-DC converter which is basically to be used as a tool for ensuring that the charge in the capacitor is efficiently and effectively transferred to the rechargeable battery and hence reduce power loses or voltage leaks.

Week 5, The fails and wins

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A picture of Shaumik trying to 3D print the aqueduct-like structure

We decided to go to the innovation studio to perform some tasks on the project. the first thing we did was to use the soldering iron to solder all the defective piezo and then tested them all out to make sure they were working. we then connected the set of piezo on a board to test whether series and parallel connections produced the most voltage since our previous test did not give any strong confirmation for either. after testing which connection works best, we then set up a circuit consisting of a 470 micro farad capacitor which was connected in series with a diode to ensure there is unidirectional flow of voltage and hence current. other component were also attached to it and through a continuous application of pressure to the piezo disc, we were able to charge the capacitor to about 1.9volts which was very constant until the capacitor was discharged. we attempted to 3D print an aqueduct-like structure to focus the pressure on the piezo crystals. this was however not successful as the 3D printer was malfunctioning

Week four, engineers do more

Figure 1. Daniel sharing his research with the group

Week 4, we were concentrating more on getting our specs right. Our timeline suggested that we had to begin with the electrical design, but we were still waiting more our piezo crystals order, that we got the night after lab. We then proceeded with finishing the Creo model of the shoe sole and we tried to mess around with the electrical devices we got from the lab. We started with a breadboard and connected diodes, resistors and capacitors trying to build a functional circuit, using a 9 V battery as the power source. While playing with the circuits, we did some research online about the optimal capacitance that we should be using for the circuit we were intending to build. We also got the chance to talk to Dr. Fred Allen to get an idea of how to control the amount of voltage going to the capacitor using a voltage regulator. After lab we headed to the Electrical Engineering department in Bossone to get the voltage regulator and a multi-meter to use when working at the dorm.

"Piezo board" and other shocking discoveries

Us measuring the voltage of the piezo board

Our previous tests so far have been on only a single piezo transducer. This week we devoted most of our time to learning the most effective ways to gain the most energy out of multiple piezo crystals. We first created a cardboard cut-out of a traced shoe, lovingly donated by one of our group members. However, we realized the best way to start would be using a square shape, like a breadboard for a proof of concept. Taking inspiration from numerous sources online, we found that the best way to arrange the piezo crystals was in series horizontally, with a parallel arrangement running vertically at the ends. It was also learned that having a stud, or any other hard, non-conductive object placed on top of the piezo would increase the electrical output via focusing the pressure to a smaller area. These two facts led us to our "piezo board," a proof of concept design that output a steady charge of 20 volts. Outside of lab, it was also learned that piezo crystals have the largest output, when attached to a foam, or any other easily compressible surface.

Week 4 - Pressure Map and Feet Paint

In order to create a piezoelectric shoe, we needed to determine where the most pressure is applied while walking. This pressure map would be the input of our device, and determine the most optimal location to place the piezo crystals. Along with research, we conducted a short experiment to create a pressure map. We put a thin layer of red paint on a piece of card board, stepped on it, and then walked across a transparent plastic film. Thus, areas of low pressure left paint on the film, and areas of very high pressure would displace the paint to areas of less pressure. Two members of the group performed the experiment, taking 5 steps.

Figure 1: Results of first trial of feet pressure map experiment

This is the result after the first trial. As a result, the most optimal positions for the piezo crystals has been graphically determined.

Week 3 - Noobs go online

For our outside class activity, we ordered fifteen sets of piezoelectric disc plates which were our major component in the generating the electrical energy. we decided to order this number of piezoelectric discs because the voltage or current produced by just one piezoelectric plate is not enough to recharge our targeted source which is supposed to have a voltage of 3V minimum. the piezoelectric plates are scheduled for arrival on Tuesday 4/25/2017.
In addition to ordering the piezoelectric disc plates, we also researched on the various components to include in the circuit and also found some suitable ways in which the capacitors used in the circuit can be used to recharge the secondary battery.

Week 3 - Engineers roll up their sleeves.

Week 3 was when we actually started working on the proposed project. We are a group of 4, and decided to pair up so that one group could work on the 3-D Creo design, while the other group could start researching about the electrical design. Daniel and Felix started to work on Creo, they already had the measurements taken from the previous week at the dorm. Some parts of the design will include 3-D printing, so it was easier to use Creo because we all learnt how to use this software in fall term. In the meanwhile, Shaumik and Kimtee toured the laboratory to find electrical tools they could use to design the circuit, also as a way to minimize costs of ordering the devices. The could find diodes, resistors, breadboards, wires, batteries and switches. Since the group did not order the main device to generate energy yet, we designed our first, most basic circuit with batteries as power supply. The circuit was functional and we intend to electrical design upon this basis itself. At the end of lab, we had the electrical and mechanical design both started.

The "Shoe" idea

During the first two weeks of this spring term, we brainstormed on how we can assist human with their daily activities. All of us being Biomedical Engineering majors, we started through ideas that were more inclined toward medical assisted devices and our initial ideas were:

A Matlab based disease tracker,

Device to aid blind people, using ultrasound,

Glasses for color blindness,

Bioprocess simulator for research testing, to decrease animal testing,

Conversion of body heat to electrical energy.

However, most of the ideas required lot of expertise and because of the time constraint too, we came up with a simpler and doable idea in 10 (or 8) weeks. 

The idea is as follows: 

We were discussing about ways of converting mechanical energy to electrical energy, and came up with the idea of using springs and piston in a shoe sole to convert the compression or pressure generated when a person walks, to electrical energy using a transducer. With some further research, we came across the piezoelectric transducer mechanism that we can use to convert the pressure exerted on the crystals to electrical signals. We then started brainstorming about the ways through which we can use that energy to help people. The first idea was to connect a USB port to the shoe so that the user can charge their medical devices like cochlear ear implant, Fitbits, blood sugar monitor, watches and phones during emergency circumstances. However, the main constraint here was that all these devices use different kinds of batteries. We then settled for the idea of storing the charges created to charge a specific type of battery that the person can use in different ways later. One of the rechargeable batteries considered was the NiMH battery that is also compatible with NiCD batteries. This is how we came up with the "Shoe Charger" idea. 

We believe that this project is a realistic project to complete with team work within the time limit. 

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